Trophoblasts are specialized cells that make up the outer layer of a blastocyst, which is a hollow ball of cells that forms in the earliest stages of embryonic development. In humans, this process occurs about 5-6 days after fertilization. The blastocyst consists of an inner cell mass (which will eventually become the embryo) and an outer layer of trophoblasts.

Trophoblasts play a crucial role in implantation, which is the process by which the blastocyst attaches to and invades the lining of the uterus. Once implanted, the trophoblasts differentiate into two main layers: the cytotrophoblasts (which are closer to the inner cell mass) and the syncytiotrophoblasts (which form a multinucleated layer that is in direct contact with the maternal tissues).

The cytotrophoblasts proliferate and fuse to form the syncytiotrophoblasts, which have several important functions. They secrete enzymes that help to degrade and remodel the extracellular matrix of the uterine lining, allowing the blastocyst to implant more deeply. They also form a barrier between the maternal and fetal tissues, helping to protect the developing embryo from the mother's immune system.

Additionally, trophoblasts are responsible for the formation of the placenta, which provides nutrients and oxygen to the developing fetus and removes waste products. The syncytiotrophoblasts in particular play a key role in this process by secreting hormones such as human chorionic gonadotropin (hCG), which helps to maintain pregnancy, and by forming blood vessels that allow for the exchange of nutrients and waste between the mother and fetus.

Abnormalities in trophoblast development or function can lead to a variety of pregnancy-related complications, including preeclampsia, intrauterine growth restriction, and gestational trophoblastic diseases such as hydatidiform moles and choriocarcinomas.

The placenta is an organ that develops in the uterus during pregnancy and provides oxygen and nutrients to the growing baby through the umbilical cord. It also removes waste products from the baby's blood. The placenta attaches to the wall of the uterus, and the baby's side of the placenta contains many tiny blood vessels that connect to the baby's circulatory system. This allows for the exchange of oxygen, nutrients, and waste between the mother's and baby's blood. After the baby is born, the placenta is usually expelled from the uterus in a process called afterbirth.

Placentation is the process by which the placenta, an organ that provides nutrients and oxygen to the developing fetus and removes waste products, is formed and develops during pregnancy. It involves the attachment of the fertilized egg (embryo) to the uterine wall and the development of specialized structures that facilitate the exchange of gases, nutrients, and waste between the mother and the fetus.

In humans, placentation begins when the embryo implants into the endometrium, or the lining of the uterus, about 6-10 days after fertilization. The outer layer of the embryo, called the trophoblast, invades the endometrial tissue and forms a structure called the placenta.

The placenta consists of both maternal and fetal tissues. The fetal portion of the placenta is derived from the chorionic villi, which are finger-like projections that develop on the surface of the embryo and increase the surface area for exchange. The maternal portion of the placenta is made up of modified endometrial tissue called decidua.

The placenta grows and develops throughout pregnancy, providing a vital connection between the mother and fetus. Proper placentation is essential for a healthy pregnancy and fetal development. Abnormalities in placentation can lead to complications such as preeclampsia, preterm labor, and intrauterine growth restriction.

Pregnancy is a physiological state or condition where a fertilized egg (zygote) successfully implants and grows in the uterus of a woman, leading to the development of an embryo and finally a fetus. This process typically spans approximately 40 weeks, divided into three trimesters, and culminates in childbirth. Throughout this period, numerous hormonal and physical changes occur to support the growing offspring, including uterine enlargement, breast development, and various maternal adaptations to ensure the fetus's optimal growth and well-being.

Chorionic villi are finger-like projections of the chorion, which is the outermost extraembryonic membrane in a developing embryo. These structures are composed of both fetal and maternal tissues and play a crucial role in the early stages of pregnancy by providing a site for exchange of nutrients and waste products between the mother and the developing fetus.

Chorionic villi contain fetal blood vessels that are surrounded by stromal cells, trophoblasts, and connective tissue. They are formed during the process of implantation, when the fertilized egg attaches to the uterine wall. The chorionic villi continue to grow and multiply as the placenta develops, eventually forming a highly vascular and specialized organ that supports fetal growth and development throughout pregnancy.

One important function of chorionic villi is to serve as the site for the production of human chorionic gonadotropin (hCG), a hormone that can be detected in the mother's blood and urine during early pregnancy. This hormone plays a critical role in maintaining pregnancy by signaling the corpus luteum to continue producing progesterone, which helps to prevent menstruation and support fetal growth.

Abnormalities in chorionic villi can lead to various pregnancy complications, such as miscarriage, stillbirth, or intrauterine growth restriction. For this reason, chorionic villus sampling (CVS) is a diagnostic procedure that may be performed during early pregnancy to obtain fetal cells for genetic testing and diagnosis of chromosomal abnormalities or other genetic disorders.

Choriocarcinoma is a rapidly growing and invasive type of gestational trophoblastic disease (GTD), which are abnormal growths that develop in the tissues that are supposed to become the placenta during pregnancy. It occurs when a malignant tumor develops from trophoblast cells, which are normally found in the developing embryo and help to form the placenta.

Choriocarcinoma can occur after any type of pregnancy, including normal pregnancies, molar pregnancies (a rare mass that forms inside the uterus after conception), or ectopic pregnancies (when a fertilized egg implants outside the uterus). It is characterized by the presence of both trophoblastic and cancerous cells, which can produce human chorionic gonadotropin (hCG) hormone.

Choriocarcinoma can spread quickly to other parts of the body, such as the lungs, liver, brain, or vagina, through the bloodstream. It is important to diagnose and treat choriocarcinoma early to prevent serious complications and improve the chances of a successful treatment outcome. Treatment typically involves surgery, chemotherapy, or radiation therapy.

The first trimester of pregnancy is defined as the period of gestational development that extends from conception (fertilization of the egg by sperm) to the end of the 13th week. This critical phase marks significant transformations in both the mother's body and the growing embryo/fetus.

During the first trimester, the fertilized egg implants into the uterine lining (implantation), initiating a series of complex interactions leading to the formation of the placenta - an organ essential for providing nutrients and oxygen to the developing fetus while removing waste products. Simultaneously, the embryo undergoes rapid cell division and differentiation, giving rise to various organs and systems. By the end of the first trimester, most major structures are present, although they continue to mature and grow throughout pregnancy.

The mother may experience several physiological changes during this time, including:
- Morning sickness (nausea and vomiting)
- Fatigue
- Breast tenderness
- Frequent urination
- Food aversions or cravings
- Mood swings

Additionally, hormonal shifts can cause various symptoms and prepare the body for potential changes in lactation, posture, and pelvic alignment as pregnancy progresses. Regular prenatal care is crucial during this period to monitor both maternal and fetal wellbeing, identify any potential complications early on, and provide appropriate guidance and support throughout the pregnancy.

The decidua is a specialized type of tissue that lines the uterus during pregnancy. It forms after the implantation of a fertilized egg (embryo) into the uterine lining, and it plays an important role in supporting the growth and development of the embryo and fetus.

The decidua is composed of several layers, including the decidual capsularis, which surrounds the embryo, and the decidual parietalis, which lines the rest of the uterus. The tissue is rich in blood vessels and contains a variety of immune cells that help to protect the developing fetus from infection.

During pregnancy, the decidua produces various hormones and growth factors that support the growth of the placenta, which provides nutrients and oxygen to the fetus. After the birth of the baby, the decidua is shed along with the placenta in a process called childbirth or parturition.

It's worth noting that abnormalities in the decidua can contribute to pregnancy complications such as preeclampsia, preterm labor, and miscarriage.

Embryo implantation is the process by which a fertilized egg, or embryo, becomes attached to the wall of the uterus (endometrium) and begins to receive nutrients from the mother's blood supply. This process typically occurs about 6-10 days after fertilization and is a critical step in the establishment of a successful pregnancy.

During implantation, the embryo secretes enzymes that help it to burrow into the endometrium, while the endometrium responds by producing receptors for the embryo's enzymes and increasing blood flow to the area. The embryo then begins to grow and develop, eventually forming the placenta, which will provide nutrients and oxygen to the developing fetus throughout pregnancy.

Implantation is a complex process that requires precise timing and coordination between the embryo and the mother's body. Factors such as age, hormonal imbalances, and uterine abnormalities can affect implantation and increase the risk of miscarriage or difficulty becoming pregnant.

"Pregnancy proteins" is not a standard medical term, but it may refer to specific proteins that are produced or have increased levels during pregnancy. Two common pregnancy-related proteins are:

1. Human Chorionic Gonadotropin (hCG): A hormone produced by the placenta shortly after fertilization. It is often detected in urine or blood tests to confirm pregnancy. Its primary function is to maintain the corpus luteum, which produces progesterone and estrogen during early pregnancy until the placenta takes over these functions.

2. Pregnancy-Specific beta-1 Glycoprotein (SP1): A protein produced by the placental trophoblasts during pregnancy. Its function is not well understood, but it may play a role in implantation, placentation, and protection against the mother's immune system. SP1 levels increase throughout pregnancy and are used as a marker for fetal growth and well-being.

These proteins have clinical significance in monitoring pregnancy progression, detecting potential complications, and diagnosing certain pregnancy-related conditions.

HLA-G antigens are a type of human leukocyte antigen (HLA) class Ib molecule that plays a crucial role in the immune system. HLA molecules are responsible for presenting pieces of proteins from inside the cell to the surface, where they can be recognized by the immune system's T-cells.

HLA-G antigens are primarily expressed in fetal tissues, including trophoblast cells that make up the placenta, and are involved in protecting the fetus from rejection by the mother's immune system during pregnancy. They have also been found to have immunosuppressive effects in other contexts, such as in cancer and transplantation.

HLA-G antigens are highly polymorphic, meaning that there are many different variations or "alleles" of the HLA-G gene that can be inherited from each parent. These genetic differences can affect the structure and function of the HLA-G molecule and may have implications for disease susceptibility and immune responses.

Pre-eclampsia is a pregnancy-related disorder, typically characterized by the onset of high blood pressure (hypertension) and damage to organs, such as the kidneys, after the 20th week of pregnancy. It is often accompanied by proteinuria, which is the presence of excess protein in the urine. Pre-eclampsia can lead to serious complications for both the mother and the baby if left untreated or unmanaged.

The exact causes of pre-eclampsia are not fully understood, but it is believed that placental issues, genetic factors, and immune system problems may contribute to its development. Risk factors include first-time pregnancies, history of pre-eclampsia in previous pregnancies, chronic hypertension, obesity, older age (35 or older), and assisted reproductive technology (ART) pregnancies.

Pre-eclampsia can progress to a more severe form called eclampsia, which is characterized by the onset of seizures. HELLP syndrome, another severe complication, involves hemolysis (breaking down of red blood cells), elevated liver enzymes, and low platelet count.

Early detection and management of pre-eclampsia are crucial to prevent severe complications. Regular prenatal care, including frequent blood pressure checks and urine tests, can help identify early signs of the condition. Treatment typically involves close monitoring, medication to lower blood pressure, corticosteroids to promote fetal lung maturity, and, in some cases, delivery of the baby if the mother's or baby's health is at risk.

Placental diseases, also known as placental pathologies, refer to a group of conditions that affect the development and function of the placenta during pregnancy. The placenta is an organ that develops in the uterus during pregnancy and provides oxygen and nutrients to the developing fetus while removing waste products.

Placental diseases can have serious consequences for both the mother and the fetus, including preterm labor, growth restriction, stillbirth, and long-term health problems for the child. Some common placental diseases include:

1. Placental abruption: This occurs when the placenta separates from the uterine wall before delivery, causing bleeding and potentially harming the fetus.
2. Placental previa: This is a condition where the placenta implants in the lower part of the uterus, covering the cervix. It can cause bleeding and may require cesarean delivery.
3. Preeclampsia: This is a pregnancy-related disorder characterized by high blood pressure and damage to organs such as the liver and kidneys. Placental dysfunction is thought to play a role in its development.
4. Intrauterine growth restriction (IUGR): This occurs when the fetus does not grow properly due to poor placental function, leading to low birth weight and potential health problems.
5. Chorioamnionitis: This is an infection of the membranes surrounding the fetus, which can lead to preterm labor and other complications.
6. Placental infarction: This occurs when a portion of the placenta dies due to a lack of blood flow, which can lead to growth restriction or stillbirth.

Prompt diagnosis and treatment of placental diseases are essential for ensuring the best possible outcomes for both the mother and the fetus.

Giant cells are large, multinucleated cells that result from the fusion of monocytes or macrophages. They can be found in various types of inflammatory and degenerative lesions, including granulomas, which are a hallmark of certain diseases such as tuberculosis and sarcoidosis. There are several types of giant cells, including:

1. Langhans giant cells: These have a horseshoe-shaped or crescentic arrangement of nuclei around the periphery of the cell. They are typically found in granulomas associated with infectious diseases such as tuberculosis and histoplasmosis.
2. Foreign body giant cells: These form in response to the presence of foreign material, such as a splinter or suture, in tissue. The nuclei are usually scattered throughout the cell cytoplasm.
3. Touton giant cells: These are found in certain inflammatory conditions, such as xanthomatosis and granulomatous slack skin. They have a central core of lipid-laden histiocytes surrounded by a ring of nuclei.
4. Osteoclast giant cells: These are multinucleated cells responsible for bone resorption. They can be found in conditions such as giant cell tumors of bone and Paget's disease.

It is important to note that the presence of giant cells alone does not necessarily indicate a specific diagnosis, and their significance must be interpreted within the context of the overall clinical and pathological findings.

A blastocyst is a stage in the early development of a fertilized egg, or embryo, in mammals. It occurs about 5-6 days after fertilization and consists of an outer layer of cells called trophoblasts, which will eventually form the placenta, and an inner cell mass, which will give rise to the fetus. The blastocyst is characterized by a fluid-filled cavity called the blastocoel. This stage is critical for the implantation of the embryo into the uterine lining.

The chorion is the outermost fetal membrane that surrounds the developing conceptus (the embryo or fetus and its supporting structures). It forms early in pregnancy as an extraembryonic structure, meaning it arises from cells that will not become part of the actual body of the developing organism. The chorion plays a crucial role in pregnancy by contributing to the formation of the placenta, which provides nutrients and oxygen to the growing embryo/fetus and removes waste products.

One of the most important functions of the chorion is to produce human chorionic gonadotropin (hCG), a hormone that signals the presence of pregnancy and maintains the corpus luteum, a temporary endocrine structure in the ovary that produces progesterone during early pregnancy. Progesterone is essential for preparing the uterus for implantation and maintaining the pregnancy.

The chorion consists of two layers: an inner cytotrophoblast layer and an outer syncytiotrophoblast layer. The cytotrophoblast layer is made up of individual cells, while the syncytiotrophoblast layer is a multinucleated mass of fused cytotrophoblast cells. These layers interact with the maternal endometrium (the lining of the uterus) to form the placenta and facilitate exchange between the mother and the developing fetus.

In summary, the chorion is a vital extraembryonic structure in pregnancy that contributes to the formation of the placenta, produces hCG, and interacts with the maternal endometrium to support fetal development.

Maternal-fetal exchange, also known as maternal-fetal transport or placental transfer, refers to the physiological process by which various substances are exchanged between the mother and fetus through the placenta. This exchange includes the transfer of oxygen and nutrients from the mother's bloodstream to the fetal bloodstream, as well as the removal of waste products and carbon dioxide from the fetal bloodstream to the mother's bloodstream.

The process occurs via passive diffusion, facilitated diffusion, and active transport mechanisms across the placental barrier, which is composed of fetal capillary endothelial cells, the extracellular matrix, and the syncytiotrophoblast layer of the placenta. The maternal-fetal exchange is crucial for the growth, development, and survival of the fetus throughout pregnancy.

Placental lactogen is a hormone produced by the placenta during pregnancy in humans and some other mammals. It is similar in structure to human growth hormone and prolactin, and has both growth-promoting and lactogenic (milk-producing) properties. Placental lactogen plays an important role in regulating maternal metabolism during pregnancy, promoting the growth and development of the fetus, and preparing the mother's body for lactation after birth. It helps to stimulate the growth of the mammary glands and the production of milk by increasing the availability of nutrients such as glucose, amino acids, and fatty acids in the mother's bloodstream. Placental lactogen also helps to regulate the mother's insulin sensitivity, which can affect her energy levels and the growth of the fetus.

The uterus, also known as the womb, is a hollow, muscular organ located in the female pelvic cavity, between the bladder and the rectum. It has a thick, middle layer called the myometrium, which is composed of smooth muscle tissue, and an inner lining called the endometrium, which provides a nurturing environment for the fertilized egg to develop into a fetus during pregnancy.

The uterus is where the baby grows and develops until it is ready for birth through the cervix, which is the lower, narrow part of the uterus that opens into the vagina. The uterus plays a critical role in the menstrual cycle as well, by shedding its lining each month if pregnancy does not occur.

The endometrium is the innermost layer of the uterus, which lines the uterine cavity and has a critical role in the menstrual cycle and pregnancy. It is composed of glands and blood vessels that undergo cyclic changes under the influence of hormones, primarily estrogen and progesterone. During the menstrual cycle, the endometrium thickens in preparation for a potential pregnancy. If fertilization does not occur, it will break down and be shed, resulting in menstruation. In contrast, if implantation takes place, the endometrium provides essential nutrients to support the developing embryo and placenta throughout pregnancy.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

Chorionic Gonadotropin (hCG) is a hormone that is produced during pregnancy. It is produced by the placenta after implantation of the fertilized egg in the uterus. The main function of hCG is to prevent the disintegration of the corpus luteum, which is a temporary endocrine structure that forms in the ovary after ovulation and produces progesterone during early pregnancy. Progesterone is essential for maintaining the lining of the uterus and supporting the pregnancy.

hCG can be detected in the blood or urine as early as 10 days after conception, and its levels continue to rise throughout the first trimester of pregnancy. In addition to its role in maintaining pregnancy, hCG is also used as a clinical marker for pregnancy and to monitor certain medical conditions such as gestational trophoblastic diseases.

Cell differentiation is the process by which a less specialized cell, or stem cell, becomes a more specialized cell type with specific functions and structures. This process involves changes in gene expression, which are regulated by various intracellular signaling pathways and transcription factors. Differentiation results in the development of distinct cell types that make up tissues and organs in multicellular organisms. It is a crucial aspect of embryonic development, tissue repair, and maintenance of homeostasis in the body.

"Animal pregnancy" is not a term that is typically used in medical definitions. However, in biological terms, animal pregnancy refers to the condition where a fertilized egg (or eggs) implants and develops inside the reproductive tract of a female animal, leading to the birth of offspring (live young).

The specific details of animal pregnancy can vary widely between different species, with some animals exhibiting phenomena such as placental development, gestation periods, and hormonal changes that are similar to human pregnancy, while others may have very different reproductive strategies.

It's worth noting that the study of animal pregnancy and reproduction is an important area of biological research, as it can provide insights into fundamental mechanisms of embryonic development, genetics, and evolution.

Uterine neoplasms refer to abnormal growths in the uterus, which can be benign (non-cancerous) or malignant (cancerous). These growths can originate from different types of cells within the uterus, leading to various types of uterine neoplasms. The two main categories of uterine neoplasms are endometrial neoplasms and uterine sarcomas.

Endometrial neoplasms develop from the endometrium, which is the inner lining of the uterus. Most endometrial neoplasms are classified as endometrioid adenocarcinomas, arising from glandular cells in the endometrium. Other types include serous carcinoma, clear cell carcinoma, and mucinous carcinoma.

Uterine sarcomas, on the other hand, are less common and originate from the connective tissue (stroma) or muscle (myometrium) of the uterus. Uterine sarcomas can be further divided into several subtypes, such as leiomyosarcoma, endometrial stromal sarcoma, and undifferentiated uterine sarcoma.

Uterine neoplasms can cause various symptoms, including abnormal vaginal bleeding or discharge, pelvic pain, and difficulty urinating or having bowel movements. The diagnosis typically involves a combination of imaging tests (such as ultrasound, CT, or MRI scans) and tissue biopsies to determine the type and extent of the neoplasm. Treatment options depend on the type, stage, and patient's overall health but may include surgery, radiation therapy, chemotherapy, or hormone therapy.

Immunohistochemistry (IHC) is a technique used in pathology and laboratory medicine to identify specific proteins or antigens in tissue sections. It combines the principles of immunology and histology to detect the presence and location of these target molecules within cells and tissues. This technique utilizes antibodies that are specific to the protein or antigen of interest, which are then tagged with a detection system such as a chromogen or fluorophore. The stained tissue sections can be examined under a microscope, allowing for the visualization and analysis of the distribution and expression patterns of the target molecule in the context of the tissue architecture. Immunohistochemistry is widely used in diagnostic pathology to help identify various diseases, including cancer, infectious diseases, and immune-mediated disorders.

Gestational age is the length of time that has passed since the first day of the last menstrual period (LMP) in pregnant women. It is the standard unit used to estimate the age of a pregnancy and is typically expressed in weeks. This measure is used because the exact date of conception is often not known, but the start of the last menstrual period is usually easier to recall.

It's important to note that since ovulation typically occurs around two weeks after the start of the LMP, gestational age is approximately two weeks longer than fetal age, which is the actual time elapsed since conception. Medical professionals use both gestational and fetal age to track the development and growth of the fetus during pregnancy.

Placental circulation refers to the specialized circulatory system that develops during pregnancy to allow for the exchange of nutrients, oxygen, and waste products between the mother's blood and the fetal blood in the placenta. The placenta is a highly vascular organ that grows within the uterus and is connected to the developing fetus via the umbilical cord.

In the maternal side of the placenta, the spiral arteries branch into smaller vessels called the intervillous spaces, where they come in close contact with the fetal blood vessels within the villi (finger-like projections) of the placenta. The intervillous spaces are filled with maternal blood that flows around the villi, allowing for the exchange of gases and nutrients between the two circulations.

On the fetal side, the umbilical cord contains two umbilical arteries that carry oxygen-depleted blood from the fetus to the placenta, and one umbilical vein that returns oxygenated blood back to the fetus. The umbilical arteries branch into smaller vessels within the villi, where they exchange gases and nutrients with the maternal blood in the intervillous spaces.

Overall, the placental circulation is a crucial component of fetal development, allowing for the growing fetus to receive the necessary oxygen and nutrients to support its growth and development.

The third trimester of pregnancy is the final stage of pregnancy that lasts from week 29 until birth, which typically occurs around the 40th week. During this period, the fetus continues to grow and mature, gaining weight rapidly. The mother's body also prepares for childbirth by dilating the cervix and producing milk in preparation for breastfeeding. Regular prenatal care is crucial during this time to monitor the health of both the mother and the developing fetus, as well as to prepare for delivery.

Fibroblast Growth Factor 4 (FGF4) is a growth factor that belongs to the fibroblast growth factor family. It plays a crucial role in various biological processes, including embryonic development, cell survival, proliferation, and differentiation. Specifically, FGF4 has been implicated in the development of the musculoskeletal system, where it helps regulate the growth and patterning of limbs and bones.

FGF4 exerts its effects by binding to specific receptors on the surface of target cells, known as fibroblast growth factor receptors (FGFRs). This interaction triggers a cascade of intracellular signaling events that ultimately lead to changes in gene expression and cell behavior.

In addition to its role in development, FGF4 has also been implicated in various pathological processes, including cancer. For example, elevated levels of FGF4 have been observed in certain types of tumors, where it may contribute to tumor growth and progression by promoting the survival and proliferation of cancer cells.

A hydatidiform mole, also known as a molar pregnancy, is a type of gestational trophoblastic disease (GTD), which is a group of rare disorders that involve abnormal growth of the placental tissue.

In a hydatidiform mole, there is an abnormal fertilization event leading to the growth of a mass of grapelike cysts in the uterus instead of a normal pregnancy. The chromosomes from the sperm and egg do not combine properly, resulting in an extra set of chromosomes, which leads to the development of the mole.

Hydatidiform moles can be complete or partial:

* Complete hydatidiform mole (CHM): This type arises when an egg without a nucleus is fertilized by one or two sperm, leading to the growth of abnormal placental tissue with no embryo. The chromosomes come from the father only, and there are typically 46 chromosomes, all of paternal origin.
* Partial hydatidiform mole (PHM): This type occurs when an egg is fertilized by two sperm or a single sperm that duplicates itself, resulting in an abnormal placenta with some fetal tissue. The chromosomes are of both maternal and paternal origin, and the placental tissue has a mix of normal and abnormal cells.

Hydatidiform moles can cause vaginal bleeding, rapid uterine enlargement, and high levels of human chorionic gonadotropin (hCG) hormone in the blood. They are usually detected during an ultrasound exam and require medical treatment to prevent complications such as gestational trophoblastic neoplasia, a malignant form of GTD that can spread to other organs.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

Developmental gene expression regulation refers to the processes that control the activation or repression of specific genes during embryonic and fetal development. These regulatory mechanisms ensure that genes are expressed at the right time, in the right cells, and at appropriate levels to guide proper growth, differentiation, and morphogenesis of an organism.

Developmental gene expression regulation is a complex and dynamic process involving various molecular players, such as transcription factors, chromatin modifiers, non-coding RNAs, and signaling molecules. These regulators can interact with cis-regulatory elements, like enhancers and promoters, to fine-tune the spatiotemporal patterns of gene expression during development.

Dysregulation of developmental gene expression can lead to various congenital disorders and developmental abnormalities. Therefore, understanding the principles and mechanisms governing developmental gene expression regulation is crucial for uncovering the etiology of developmental diseases and devising potential therapeutic strategies.

Keratin-7 is not a medical term itself, but it is a specific type of keratin protein that is often used in pathology as a marker for certain types of carcinomas. Keratins are a family of fibrous proteins that make up the structural framework of epithelial cells, which line the surfaces and glands of the body.

Keratin-7 is typically expressed in simple epithelia, such as those found in the gastrointestinal tract, pancreas, bile ducts, and respiratory and genitourinary tracts. It can be used as a marker to help identify carcinomas that arise from these tissues, such as adenocarcinomas of the pancreas or biliary system.

In medical terminology, keratin-7 positivity is often reported in the pathology report of a biopsy or surgical specimen to indicate the presence of this protein in cancer cells. This information can be helpful in determining the origin and behavior of the tumor, as well as guiding treatment decisions.

Trophoblastic neoplasms are a group of rare tumors that originate from the trophoblast, which is the outer layer of cells that surrounds a developing embryo and helps to form the placenta during pregnancy. These tumors can be benign or malignant and are characterized by their ability to produce human chorionic gonadotropin (hCG), a hormone that is normally produced during pregnancy.

There are several types of trophoblastic neoplasms, including:

1. Hydatidiform mole: A benign growth that forms in the uterus when a fertilized egg implants but does not develop into a normal embryo. There are two types of hydatidiform moles: complete and partial. Complete moles have no fetal tissue, while partial moles have some fetal tissue.
2. Invasive mole: A malignant form of hydatidiform mole that invades the uterine wall and may spread to other parts of the body.
3. Choriocarcinoma: A rapidly growing and highly invasive malignant tumor that can arise from a hydatidiform mole, a normal pregnancy, or an ectopic pregnancy. It can spread quickly to other parts of the body, such as the lungs, liver, and brain.
4. Placental site trophoblastic tumor (PSTT): A rare type of trophoblastic neoplasm that arises from the cells that attach the placenta to the uterine wall. It is usually slow-growing but can be aggressive in some cases.
5. Epithelioid trophoblastic tumor (ETT): Another rare type of trophoblastic neoplasm that arises from the cells that form the placental villi. It is typically low-grade and has a good prognosis, but it can recur in some cases.

The treatment for trophoblastic neoplasms depends on the type and stage of the tumor. Treatment options may include surgery, chemotherapy, radiation therapy, or a combination of these approaches. Regular monitoring of hCG levels is also important to ensure that the tumor has been completely removed and to detect any recurrence early.

Cell movement, also known as cell motility, refers to the ability of cells to move independently and change their location within tissue or inside the body. This process is essential for various biological functions, including embryonic development, wound healing, immune responses, and cancer metastasis.

There are several types of cell movement, including:

1. **Crawling or mesenchymal migration:** Cells move by extending and retracting protrusions called pseudopodia or filopodia, which contain actin filaments. This type of movement is common in fibroblasts, immune cells, and cancer cells during tissue invasion and metastasis.
2. **Amoeboid migration:** Cells move by changing their shape and squeezing through tight spaces without forming protrusions. This type of movement is often observed in white blood cells (leukocytes) as they migrate through the body to fight infections.
3. **Pseudopodial extension:** Cells extend pseudopodia, which are temporary cytoplasmic projections containing actin filaments. These protrusions help the cell explore its environment and move forward.
4. **Bacterial flagellar motion:** Bacteria use a whip-like structure called a flagellum to propel themselves through their environment. The rotation of the flagellum is driven by a molecular motor in the bacterial cell membrane.
5. **Ciliary and ependymal movement:** Ciliated cells, such as those lining the respiratory tract and fallopian tubes, have hair-like structures called cilia that beat in coordinated waves to move fluids or mucus across the cell surface.

Cell movement is regulated by a complex interplay of signaling pathways, cytoskeletal rearrangements, and adhesion molecules, which enable cells to respond to environmental cues and navigate through tissues.

Fetal growth retardation, also known as intrauterine growth restriction (IUGR), is a condition in which a fetus fails to grow at the expected rate during pregnancy. This can be caused by various factors such as maternal health problems, placental insufficiency, chromosomal abnormalities, and genetic disorders. The fetus may be smaller than expected for its gestational age, have reduced movement, and may be at risk for complications during labor and delivery. It is important to monitor fetal growth and development closely throughout pregnancy to detect any potential issues early on and provide appropriate medical interventions.

A mammalian embryo is the developing offspring of a mammal, from the time of implantation of the fertilized egg (blastocyst) in the uterus until the end of the eighth week of gestation. During this period, the embryo undergoes rapid cell division and organ differentiation to form a complex structure with all the major organs and systems in place. This stage is followed by fetal development, which continues until birth. The study of mammalian embryos is important for understanding human development, evolution, and reproductive biology.

Embryonic development is the series of growth and developmental stages that occur during the formation and early growth of the embryo. In humans, this stage begins at fertilization (when the sperm and egg cell combine) and continues until the end of the 8th week of pregnancy. During this time, the fertilized egg (now called a zygote) divides and forms a blastocyst, which then implants into the uterus. The cells in the blastocyst begin to differentiate and form the three germ layers: the ectoderm, mesoderm, and endoderm. These germ layers will eventually give rise to all of the different tissues and organs in the body.

Embryonic development is a complex and highly regulated process that involves the coordinated interaction of genetic and environmental factors. It is characterized by rapid cell division, migration, and differentiation, as well as programmed cell death (apoptosis) and tissue remodeling. Abnormalities in embryonic development can lead to birth defects or other developmental disorders.

It's important to note that the term "embryo" is used to describe the developing organism from fertilization until the end of the 8th week of pregnancy in humans, after which it is called a fetus.

Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) is a laboratory technique used in molecular biology to amplify and detect specific DNA sequences. This technique is particularly useful for the detection and quantification of RNA viruses, as well as for the analysis of gene expression.

The process involves two main steps: reverse transcription and polymerase chain reaction (PCR). In the first step, reverse transcriptase enzyme is used to convert RNA into complementary DNA (cDNA) by reading the template provided by the RNA molecule. This cDNA then serves as a template for the PCR amplification step.

In the second step, the PCR reaction uses two primers that flank the target DNA sequence and a thermostable polymerase enzyme to repeatedly copy the targeted cDNA sequence. The reaction mixture is heated and cooled in cycles, allowing the primers to anneal to the template, and the polymerase to extend the new strand. This results in exponential amplification of the target DNA sequence, making it possible to detect even small amounts of RNA or cDNA.

RT-PCR is a sensitive and specific technique that has many applications in medical research and diagnostics, including the detection of viruses such as HIV, hepatitis C virus, and SARS-CoV-2 (the virus that causes COVID-19). It can also be used to study gene expression, identify genetic mutations, and diagnose genetic disorders.

Tubal pregnancy, also known as an ectopic pregnancy, is a type of pregnancy that occurs outside the uterus, usually in the fallopian tube. The fertilized egg implants and starts to develop in the tube instead of the uterine lining. This condition is not viable and can be life-threatening if not treated promptly.

The symptoms of a tubal pregnancy may include abdominal pain, vaginal bleeding, shoulder pain, dizziness or fainting, and pelvic discomfort or tenderness. If you suspect that you have a tubal pregnancy, it is important to seek medical attention immediately. Treatment options for tubal pregnancies include medication or surgery to remove the embryo and repair or remove the affected fallopian tube.

Extraembryonic membranes are specialized structures that form around the developing embryo in utero and provide vital support and protection during fetal development. There are three main extraembryonic membranes: the amnion, the chorion, and the allantois.

The amnion is the innermost membrane that surrounds the embryo itself, forming a fluid-filled sac known as the amniotic cavity. This sac provides a protective cushion for the developing embryo and helps to regulate its temperature and moisture levels.

The chorion is the outermost of the extraembryonic membranes, and it forms the boundary between the developing fetus and the mother's uterine wall. The chorion contains blood vessels that exchange nutrients and waste products with the mother's circulation, allowing for the growth and development of the fetus.

The allantois is a small membranous sac that arises from the developing fetal gut and eventually becomes part of the umbilical cord. It serves as a reservoir for fetal urine and helps to exchange waste products between the fetal and maternal circulations.

Together, these extraembryonic membranes play a critical role in supporting fetal development and ensuring a healthy pregnancy.

A Trophoblastic Tumor, Placental Site (also known as Placental Site Trophoblastic Tumor or PSTT) is a rare type of gestational trophoblastic disease (GTD), which are tumors that develop from the tissue that would normally become the placenta during pregnancy.

PSTT originates from the intermediate trophoblast cells, which invade the uterine wall and cause bleeding at the site of implantation during a normal pregnancy. These tumors typically occur in women who have had a prior pregnancy, with a median age of diagnosis around 35 years old.

PSTTs are usually slow-growing and may not cause any symptoms for an extended period. However, some common symptoms include abnormal vaginal bleeding, irregular menstrual periods, or pelvic pain. In rare cases, PSTT can metastasize to other organs such as the lungs, liver, or brain.

The diagnosis of PSTT is made through a combination of imaging studies (such as ultrasound, CT scan, or MRI) and histopathological examination of tissue samples obtained via biopsy or curettage. Treatment typically involves surgical removal of the tumor, followed by chemotherapy in cases where there is evidence of metastasis or high-risk features. Regular follow-up with serum beta-human chorionic gonadotropin (β-hCG) levels and imaging studies is essential to monitor for recurrence.

Embryo loss is a medical term that refers to the miscarriage or spontaneous abortion of an embryo, which is the developing offspring from the time of fertilization until the end of the eighth week of pregnancy. Embryo loss can occur at any point during this period and may be caused by various factors such as chromosomal abnormalities, maternal health issues, infections, environmental factors, or lifestyle habits.

Embryo loss is a common occurrence, with up to 30% of pregnancies ending in miscarriage, many of which happen before the woman even realizes she is pregnant. In most cases, embryo loss is a natural process that occurs when the body detects an abnormality or problem with the developing embryo and terminates the pregnancy to prevent further complications. However, recurrent embryo loss can be a sign of underlying medical issues and may require further evaluation and treatment.

An encyclopedia is a comprehensive reference work containing articles on various topics, usually arranged in alphabetical order. In the context of medicine, a medical encyclopedia is a collection of articles that provide information about a wide range of medical topics, including diseases and conditions, treatments, tests, procedures, and anatomy and physiology. Medical encyclopedias may be published in print or electronic formats and are often used as a starting point for researching medical topics. They can provide reliable and accurate information on medical subjects, making them useful resources for healthcare professionals, students, and patients alike. Some well-known examples of medical encyclopedias include the Merck Manual and the Stedman's Medical Dictionary.