Embryo Transfer: The transfer of mammalian embryos from an in vivo or in vitro environment to a suitable host to improve pregnancy or gestational outcome in human or animal. In human fertility treatment programs, preimplantation embryos ranging from the 4-cell stage to the blastocyst stage are transferred to the uterine cavity between 3-5 days after FERTILIZATION IN VITRO.Single Embryo Transfer: The techniques used to select and/or place only one embryo from FERTILIZATION IN VITRO into the uterine cavity to establish a singleton pregnancy.Fertilization in Vitro: An assisted reproductive technique that includes the direct handling and manipulation of oocytes and sperm to achieve fertilization in vitro.Pregnancy Rate: The ratio of the number of conceptions (CONCEPTION) including LIVE BIRTH; STILLBIRTH; and fetal losses, to the mean number of females of reproductive age in a population during a set time period.Embryo Implantation: Endometrial implantation of EMBRYO, MAMMALIAN at the BLASTOCYST stage.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Embryo, Mammalian: The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS.Cryopreservation: Preservation of cells, tissues, organs, or embryos by freezing. In histological preparations, cryopreservation or cryofixation is used to maintain the existing form, structure, and chemical composition of all the constituent elements of the specimens.Pregnancy, Multiple: The condition of carrying two or more FETUSES simultaneously.Sperm Injections, Intracytoplasmic: An assisted fertilization technique consisting of the microinjection of a single viable sperm into an extracted ovum. It is used principally to overcome low sperm count, low sperm motility, inability of sperm to penetrate the egg, or other conditions related to male infertility (INFERTILITY, MALE).Pregnancy Outcome: Results of conception and ensuing pregnancy, including LIVE BIRTH; STILLBIRTH; SPONTANEOUS ABORTION; INDUCED ABORTION. The outcome may follow natural or artificial insemination or any of the various ASSISTED REPRODUCTIVE TECHNIQUES, such as EMBRYO TRANSFER or FERTILIZATION IN VITRO.Blastocyst: A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.Live Birth: The event that a FETUS is born alive with heartbeats or RESPIRATION regardless of GESTATIONAL AGE. Such liveborn is called a newborn infant (INFANT, NEWBORN).Infertility: Inability to reproduce after a specified period of unprotected intercourse. Reproductive sterility is permanent infertility.Infertility, Female: Diminished or absent ability of a female to achieve conception.Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.Ovulation Induction: Techniques for the artifical induction of ovulation, the rupture of the follicle and release of the ovum.Chick Embryo: The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.Cleavage Stage, Ovum: The earliest developmental stage of a fertilized ovum (ZYGOTE) during which there are several mitotic divisions within the ZONA PELLUCIDA. Each cleavage or segmentation yields two BLASTOMERES of about half size of the parent cell. This cleavage stage generally covers the period up to 16-cell MORULA.Zygote Intrafallopian Transfer: A technique in assisted reproduction (REPRODUCTIVE TECHNIQUES, ASSISTED) consisting of hormonal stimulation of the ovaries, follicular aspiration of preovulatory oocytes, in-vitro fertilization, and intrafallopian transfer of zygotes at the pronuclear stage (before cleavage).Twins: Two individuals derived from two FETUSES that were fertilized at or about the same time, developed in the UTERUS simultaneously, and born to the same mother. Twins are either monozygotic (TWINS, MONOZYGOTIC) or dizygotic (TWINS, DIZYGOTIC).Oocyte Donation: Transfer of preovulatory oocytes from donor to a suitable host. Oocytes are collected, fertilized in vitro, and transferred to a host that can be human or animal.Reproductive Techniques, Assisted: Clinical and laboratory techniques used to enhance fertility in humans and animals.Reproductive Techniques: Methods pertaining to the generation of new individuals, including techniques used in selective BREEDING, cloning (CLONING, ORGANISM), and assisted reproduction (REPRODUCTIVE TECHNIQUES, ASSISTED).Embryonic Development: Morphological and physiological development of EMBRYOS.Embryonic and Fetal Development: Morphological and physiological development of EMBRYOS or FETUSES.Blastomeres: Undifferentiated cells resulting from cleavage of a fertilized egg (ZYGOTE). Inside the intact ZONA PELLUCIDA, each cleavage yields two blastomeres of about half size of the parent cell. Up to the 8-cell stage, all of the blastomeres are totipotent. The 16-cell MORULA contains outer cells and inner cells.Abortion, Spontaneous: Expulsion of the product of FERTILIZATION before completing the term of GESTATION and without deliberate interference.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).Chorionic Gonadotropin: A gonadotropic glycoprotein hormone produced primarily by the PLACENTA. Similar to the pituitary LUTEINIZING HORMONE in structure and function, chorionic gonadotropin is involved in maintaining the CORPUS LUTEUM during pregnancy. CG consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is virtually identical to the alpha subunits of the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity (CHORIONIC GONADOTROPIN, BETA SUBUNIT, HUMAN).Embryo Culture Techniques: The technique of maintaining or growing mammalian EMBRYOS in vitro. This method offers an opportunity to observe EMBRYONIC DEVELOPMENT; METABOLISM; and susceptibility to TERATOGENS.Birth Rate: The number of births in a given population per year or other unit of time.Preimplantation Diagnosis: Determination of the nature of a pathological condition or disease in the OVUM; ZYGOTE; or BLASTOCYST prior to implantation. CYTOGENETIC ANALYSIS is performed to determine the presence or absence of genetic disease.Morula: An early embryo that is a compact mass of about 16 BLASTOMERES. It resembles a cluster of mulberries with two types of cells, outer cells and inner cells. Morula is the stage before BLASTULA in non-mammalian animals or a BLASTOCYST in mammals.Gene Transfer Techniques: The introduction of functional (usually cloned) GENES into cells. A variety of techniques and naturally occurring processes are used for the gene transfer such as cell hybridization, LIPOSOMES or microcell-mediated gene transfer, ELECTROPORATION, chromosome-mediated gene transfer, TRANSFECTION, and GENETIC TRANSDUCTION. Gene transfer may result in genetically transformed cells and individual organisms.Ovarian Hyperstimulation Syndrome: A complication of OVULATION INDUCTION in infertility treatment. It is graded by the severity of symptoms which include OVARY enlargement, multiple OVARIAN FOLLICLES; OVARIAN CYSTS; ASCITES; and generalized EDEMA. The full-blown syndrome may lead to RENAL FAILURE, respiratory distress, and even DEATH. Increased capillary permeability is caused by the vasoactive substances, such as VASCULAR ENDOTHELIAL GROWTH FACTORS, secreted by the overly-stimulated OVARIES.Uterus: The hollow thick-walled muscular organ in the female PELVIS. It consists of the fundus (the body) which is the site of EMBRYO IMPLANTATION and FETAL DEVELOPMENT. Beyond the isthmus at the perineal end of fundus, is CERVIX UTERI (the neck) opening into VAGINA. Beyond the isthmi at the upper abdominal end of fundus, are the FALLOPIAN TUBES.Menotropins: Extracts of urine from menopausal women that contain high concentrations of pituitary gonadotropins, FOLLICLE STIMULATING HORMONE and LUTEINIZING HORMONE. Menotropins are used to treat infertility. The FSH:LH ratio and degree of purity vary in different preparations.Vitrification: The transformation of a liquid to a glassy solid i.e., without the formation of crystals during the cooling process.Embryo Loss: Early pregnancy loss during the EMBRYO, MAMMALIAN stage of development. In the human, this period comprises the second through eighth week after fertilization.Endometrium: The mucous membrane lining of the uterine cavity that is hormonally responsive during the MENSTRUAL CYCLE and PREGNANCY. The endometrium undergoes cyclic changes that characterize MENSTRUATION. After successful FERTILIZATION, it serves to sustain the developing embryo.Cloning, Organism: The formation of one or more genetically identical organisms derived by vegetative reproduction from a single cell. The source nuclear material can be embryo-derived, fetus-derived, or taken from an adult somatic cell.Fallopian Tube Diseases: Diseases involving the FALLOPIAN TUBES including neoplasms (FALLOPIAN TUBE NEOPLASMS); SALPINGITIS; tubo-ovarian abscess; and blockage.Oocyte Retrieval: Procedures to obtain viable OOCYTES from the host. Oocytes most often are collected by needle aspiration from OVARIAN FOLLICLES before OVULATION.Pregnancy, Ectopic: A potentially life-threatening condition in which EMBRYO IMPLANTATION occurs outside the cavity of the UTERUS. Most ectopic pregnancies (>96%) occur in the FALLOPIAN TUBES, known as TUBAL PREGNANCY. They can be in other locations, such as UTERINE CERVIX; OVARY; and abdominal cavity (PREGNANCY, ABDOMINAL).Superovulation: Occurrence or induction of release of more ova than are normally released at the same time in a given species. The term applies to both animals and humans.Nuclear Transfer Techniques: Methods of implanting a CELL NUCLEUS from a donor cell into an enucleated acceptor cell.Maternal Age: The age of the mother in PREGNANCY.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Insemination, Artificial: Artificial introduction of SEMEN or SPERMATOZOA into the VAGINA to facilitate FERTILIZATION.Pregnancy Reduction, Multifetal: Selective abortion of one or more embryos or fetuses in a multiple gestation pregnancy. The usual goal is to improve the outcome for the remaining embryos or fetuses.Buserelin: A potent synthetic analog of GONADOTROPIN-RELEASING HORMONE with D-serine substitution at residue 6, glycine10 deletion, and other modifications.Fertilization: The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.Zona Pellucida: A tough transparent membrane surrounding the OVUM. It is penetrated by the sperm during FERTILIZATION.Gene Transfer, Horizontal: The naturally occurring transmission of genetic information between organisms, related or unrelated, circumventing parent-to-offspring transmission. Horizontal gene transfer may occur via a variety of naturally occurring processes such as GENETIC CONJUGATION; GENETIC TRANSDUCTION; and TRANSFECTION. It may result in a change of the recipient organism's genetic composition (TRANSFORMATION, GENETIC).Pregnancy, Twin: The condition of carrying TWINS simultaneously.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Catheterization: Use or insertion of a tubular device into a duct, blood vessel, hollow organ, or body cavity for injecting or withdrawing fluids for diagnostic or therapeutic purposes. It differs from INTUBATION in that the tube here is used to restore or maintain patency in obstructions.Progesterone: The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.Culture Techniques: Methods of maintaining or growing biological materials in controlled laboratory conditions. These include the cultures of CELLS; TISSUES; organs; or embryo in vitro. Both animal and plant tissues may be cultured by a variety of methods. Cultures may derive from normal or abnormal tissues, and consist of a single cell type or mixed cell types.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.Ultrasonography: The visualization of deep structures of the body by recording the reflections or echoes of ultrasonic pulses directed into the tissues. Use of ultrasound for imaging or diagnostic purposes employs frequencies ranging from 1.6 to 10 megahertz.Multiple Birth Offspring: The offspring in multiple pregnancies (PREGNANCY, MULTIPLE): TWINS; TRIPLETS; QUADRUPLETS; QUINTUPLETS; etc.Freezing: Liquids transforming into solids by the removal of heat.Twinning, Monozygotic: The division of a ZYGOTE into two parts, each of which is capable of further development.Luteal Phase: The period in the MENSTRUAL CYCLE that follows OVULATION, characterized by the development of CORPUS LUTEUM, increase in PROGESTERONE production by the OVARY and secretion by the glandular epithelium of the ENDOMETRIUM. The luteal phase begins with ovulation and ends with the onset of MENSTRUATION.Gene Expression Regulation, Developmental: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.Pregnancy, Tubal: The most common (>96%) type of ectopic pregnancy in which the extrauterine EMBRYO IMPLANTATION occurs in the FALLOPIAN TUBE, usually in the ampullary region where FERTILIZATION takes place.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.Follicle Stimulating Hormone: A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Follicle-stimulating hormone stimulates GAMETOGENESIS and the supporting cells such as the ovarian GRANULOSA CELLS, the testicular SERTOLI CELLS, and LEYDIG CELLS. FSH consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity.Surrogate Mothers: Women who allow themselves to be impregnated with the understanding that the offspring are to be given over to the parents who have commissioned the surrogate.Incubators: Insulated enclosures in which temperature, humidity, and other environmental conditions can be regulated at levels optimal for growth, hatching, reproduction, or metabolic reactions.Fertility Agents, Female: Compounds which increase the capacity to conceive in females.Fallopian Tubes: A pair of highly specialized muscular canals extending from the UTERUS to its corresponding OVARY. They provide the means for OVUM collection, and the site for the final maturation of gametes and FERTILIZATION. The fallopian tube consists of an interstitium, an isthmus, an ampulla, an infundibulum, and fimbriae. Its wall consists of three histologic layers: serous, muscular, and an internal mucosal layer lined with both ciliated and secretory cells.Triplets: Three individuals derived from three FETUSES that were fertilized at or about the same time, developed in the UTERUS simultaneously, and born to the same mother.Follicular Fluid: The fluid surrounding the OVUM and GRANULOSA CELLS in the Graafian follicle (OVARIAN FOLLICLE). The follicular fluid contains sex steroids, glycoprotein hormones, plasma proteins, mucopolysaccharides, and enzymes.Ovary: The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Gonadotropin-Releasing Hormone: A decapeptide that stimulates the synthesis and secretion of both pituitary gonadotropins, LUTEINIZING HORMONE and FOLLICLE STIMULATING HORMONE. GnRH is produced by neurons in the septum PREOPTIC AREA of the HYPOTHALAMUS and released into the pituitary portal blood, leading to stimulation of GONADOTROPHS in the ANTERIOR PITUITARY GLAND.Micromanipulation: The performance of dissections, injections, surgery, etc., by the use of micromanipulators (attachments to a microscope) that manipulate tiny instruments.Estradiol: The 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids.Pregnancy, Animal: The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH.Labor Stage, First: Period from the onset of true OBSTETRIC LABOR to the complete dilatation of the CERVIX UTERI.Nafarelin: A potent synthetic agonist of GONADOTROPIN-RELEASING HORMONE with 3-(2-naphthyl)-D-alanine substitution at residue 6. Nafarelin has been used in the treatments of central PRECOCIOUS PUBERTY and ENDOMETRIOSIS.Chorionic Gonadotropin, beta Subunit, Human: The beta subunit of human CHORIONIC GONADOTROPIN. Its structure is similar to the beta subunit of LUTEINIZING HORMONE, except for the additional 30 amino acids at the carboxy end with the associated carbohydrate residues. HCG-beta is used as a diagnostic marker for early detection of pregnancy, spontaneous abortion (ABORTION, SPONTANEOUS); ECTOPIC PREGNANCY; HYDATIDIFORM MOLE; CHORIOCARCINOMA; or DOWN SYNDROME.Litter Size: The number of offspring produced at one birth by a viviparous animal.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Abortion, Veterinary: Premature expulsion of the FETUS in animals.Pregnancy Maintenance: Physiological mechanisms that sustain the state of PREGNANCY.Gamete Intrafallopian Transfer: A technique that came into use in the mid-1980's for assisted conception in infertile women with normal fallopian tubes. The protocol consists of hormonal stimulation of the ovaries, followed by laparoscopic follicular aspiration of oocytes, and then the transfer of sperm and oocytes by catheterization into the fallopian tubes.Fetal Viability: The potential of the FETUS to survive outside the UTERUS after birth, natural or induced. Fetal viability depends largely on the FETAL ORGAN MATURITY, and environmental conditions.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Uterine Contraction: Contraction of the UTERINE MUSCLE.Transfer (Psychology): Change in learning in one situation due to prior learning in another situation. The transfer can be positive (with second learning improved by first) or negative (where the reverse holds).Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Pregnancy Tests: Tests to determine whether or not an individual is pregnant.Twins, Monozygotic: Two off-spring from the same PREGNANCY. They are from a single fertilized OVUM that split into two EMBRYOS. Such twins are usually genetically identical and of the same sex.Infertility, Male: The inability of the male to effect FERTILIZATION of an OVUM after a specified period of unprotected intercourse. Male sterility is permanent infertility.Triptorelin Pamoate: A potent synthetic long-acting agonist of GONADOTROPIN-RELEASING HORMONE with D-tryptophan substitution at residue 6.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Follicle Stimulating Hormone, Human: A major gonadotropin secreted by the human adenohypophysis (PITUITARY GLAND, ANTERIOR). Follicle-stimulating hormone stimulates GAMETOGENESIS and the supporting cells such as the ovarian GRANULOSA CELLS, the testicular SERTOLI CELLS, and the LEYDIG CELLS. FSH consists of two noncovalently linked subunits, alpha and beta. The alpha subunit is common in the three human pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity.Tissue and Organ Harvesting: The procedure of removing TISSUES, organs, or specimens from DONORS for reuse, such as TRANSPLANTATION.Ovulation: The discharge of an OVUM from a rupturing follicle in the OVARY.Ovarian Follicle: An OOCYTE-containing structure in the cortex of the OVARY. The oocyte is enclosed by a layer of GRANULOSA CELLS providing a nourishing microenvironment (FOLLICULAR FLUID). The number and size of follicles vary depending on the age and reproductive state of the female. The growing follicles are divided into five stages: primary, secondary, tertiary, Graafian, and atretic. Follicular growth and steroidogenesis depend on the presence of GONADOTROPINS.Embryo Disposition: Utilization or disposal of an embryo that is fertilized but not immediately transplanted and resulting course of action.Fetal Death: Death of the developing young in utero. BIRTH of a dead FETUS is STILLBIRTH.Mice, Inbred ICRFluorescence Resonance Energy Transfer: A type of FLUORESCENCE SPECTROSCOPY using two FLUORESCENT DYES with overlapping emission and absorption spectra, which is used to indicate proximity of labeled molecules. This technique is useful for studying interactions of molecules and PROTEIN FOLDING.Administration, Intravaginal: The insertion of drugs into the vagina to treat local infections, neoplasms, or to induce labor. The dosage forms may include medicated pessaries, irrigation fluids, and suppositories.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Zebrafish: An exotic species of the family CYPRINIDAE, originally from Asia, that has been introduced in North America. They are used in embryological studies and to study the effects of certain chemicals on development.Gestational Age: The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.Cervix Mucus: A slightly alkaline secretion of the endocervical glands. The consistency and amount are dependent on the physiological hormone changes in the menstrual cycle. It contains the glycoprotein mucin, amino acids, sugar, enzymes, and electrolytes, with a water content up to 90%. The mucus is a useful protection against the ascent of bacteria and sperm into the uterus. (From Dictionary of Obstetrics and Gynecology, 1988)Clomiphene: A triphenyl ethylene stilbene derivative which is an estrogen agonist or antagonist depending on the target tissue. Note that ENCLOMIPHENE and ZUCLOMIPHENE are the (E) and (Z) isomers of Clomiphene respectively.Cervix Uteri: The neck portion of the UTERUS between the lower isthmus and the VAGINA forming the cervical canal.Quintuplets: Five individuals derived from five FETUSES that were fertilized at or about the same time, developed in the UTERUS simultaneously, and born to the same mother.Menstrual Cycle: The period from onset of one menstrual bleeding (MENSTRUATION) to the next in an ovulating woman or female primate. The menstrual cycle is regulated by endocrine interactions of the HYPOTHALAMUS; the PITUITARY GLAND; the ovaries; and the genital tract. The menstrual cycle is divided by OVULATION into two phases. Based on the endocrine status of the OVARY, there is a FOLLICULAR PHASE and a LUTEAL PHASE. Based on the response in the ENDOMETRIUM, the menstrual cycle is divided into a proliferative and a secretory phase.Adoptive Transfer: Form of passive immunization where previously sensitized immunologic agents (cells or serum) are transferred to non-immune recipients. When transfer of cells is used as a therapy for the treatment of neoplasms, it is called adoptive immunotherapy (IMMUNOTHERAPY, ADOPTIVE).Cryoprotective Agents: Substances that provide protection against the harmful effects of freezing temperatures.RNA, Transfer: The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.Gastrula: The developmental stage that follows BLASTULA or BLASTOCYST. It is characterized by the morphogenetic cell movements including invagination, ingression, and involution. Gastrulation begins with the formation of the PRIMITIVE STREAK, and ends with the formation of three GERM LAYERS, the body plan of the mature organism.Quadruplets: Four individuals derived from four FETUSES that were fertilized at or about the same time, developed in the UTERUS simultaneously, and born to the same mother.Suction: The removal of secretions, gas or fluid from hollow or tubular organs or cavities by means of a tube and a device that acts on negative pressure.Birth Weight: The mass or quantity of heaviness of an individual at BIRTH. It is expressed by units of pounds or kilograms.Body Patterning: The processes occurring in early development that direct morphogenesis. They specify the body plan ensuring that cells will proceed to differentiate, grow, and diversify in size and shape at the correct relative positions. Included are axial patterning, segmentation, compartment specification, limb position, organ boundary patterning, blood vessel patterning, etc.Follicular Phase: The period of the MENSTRUAL CYCLE representing follicular growth, increase in ovarian estrogen (ESTROGENS) production, and epithelial proliferation of the ENDOMETRIUM. Follicular phase begins with the onset of MENSTRUATION and ends with OVULATION.Patient Transfer: Interfacility or intrahospital transfer of patients. Intrahospital transfer is usually to obtain a specific kind of care and interfacility transfer is usually for economic reasons as well as for the type of care provided.In Situ Hybridization: A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Phospholipid Transfer Proteins: A ubiquitous family of proteins that transport PHOSPHOLIPIDS such as PHOSPHATIDYLINOSITOL and PHOSPHATIDYLCHOLINE between membranes. They play an important role in phospholipid metabolism during vesicular transport and SIGNAL TRANSDUCTION.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Leuprolide: A potent synthetic long-acting agonist of GONADOTROPIN-RELEASING HORMONE that regulates the synthesis and release of pituitary gonadotropins, LUTEINIZING HORMONE and FOLLICLE STIMULATING HORMONE.Delivery, Obstetric: Delivery of the FETUS and PLACENTA under the care of an obstetrician or a health worker. Obstetric deliveries may involve physical, psychological, medical, or surgical interventions.Reproductive Medicine: A medical-surgical specialty concerned with the morphology, physiology, biochemistry, and pathology of reproduction in man and other animals, and on the biological, medical, and veterinary problems of fertility and lactation. It includes ovulation induction, diagnosis of infertility and recurrent pregnancy loss, and assisted reproductive technologies such as embryo transfer, in vitro fertilization, and intrafallopian transfer of zygotes. (From Infertility and Reproductive Medicine Clinics of North America, Foreword 1990; Journal of Reproduction and Fertility, Notice to Contributors, Jan 1979)Cumulus Cells: The granulosa cells of the cumulus oophorus which surround the OVUM in the GRAAFIAN FOLLICLE. At OVULATION they are extruded with OVUM.Aneuploidy: The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).Genetic Vectors: DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Breeding: The production of offspring by selective mating or HYBRIDIZATION, GENETIC in animals or plants.Mice, Inbred C57BLMorphogenesis: The development of anatomical structures to create the form of a single- or multi-cell organism. Morphogenesis provides form changes of a part, parts, or the whole organism.Pregnancy-Specific beta 1-Glycoproteins: Glycoproteins with the electrophoretic mobility of BETA-GLOBULINS, secreted by the placental TROPHOBLASTS into the maternal bloodstream during PREGNANCY. They can be detected 18 days after OVULATION and reach 200 mg/ml at the end of pregnancy. They are associated with fetal well-being.Embryo Research: Experimentation on, or using the organs or tissues from, a human or other mammalian conceptus during the prenatal stage of development that is characterized by rapid morphological changes and the differentiation of basic structures. In humans, this includes the period from the time of fertilization to the end of the eighth week after fertilization.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Transfer Factor: Factor derived from leukocyte lysates of immune donors which can transfer both local and systemic cellular immunity to nonimmune recipients.Luteolytic Agents: Chemical compounds causing LUTEOLYSIS or degeneration.Oligospermia: A condition of suboptimal concentration of SPERMATOZOA in the ejaculated SEMEN to ensure successful FERTILIZATION of an OVUM. In humans, oligospermia is defined as a sperm count below 20 million per milliliter semen.Pregnancy, High-Risk: Pregnancy in which the mother and/or FETUS are at greater than normal risk of MORBIDITY or MORTALITY. Causes include inadequate PRENATAL CARE, previous obstetrical history (ABORTION, SPONTANEOUS), pre-existing maternal disease, pregnancy-induced disease (GESTATIONAL HYPERTENSION), and MULTIPLE PREGNANCY, as well as advanced maternal age above 35.Infant, Newborn: An infant during the first month after birth.Ectogenesis: Embryonic and fetal development that takes place in an artificial environment in vitro.Mesoderm: The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.Relaxin: A water-soluble polypeptide (molecular weight approximately 8,000) extractable from the corpus luteum of pregnancy. It produces relaxation of the pubic symphysis and dilation of the uterine cervix in certain animal species. Its role in the human pregnant female is uncertain. (Dorland, 28th ed)Gonadotropins: Hormones that stimulate gonadal functions such as GAMETOGENESIS and sex steroid hormone production in the OVARY and the TESTIS. Major gonadotropins are glycoproteins produced primarily by the adenohypophysis (GONADOTROPINS, PITUITARY) and the placenta (CHORIONIC GONADOTROPIN). In some species, pituitary PROLACTIN and PLACENTAL LACTOGEN exert some luteotropic activities.Conjugation, Genetic: A parasexual process in BACTERIA; ALGAE; FUNGI; and ciliate EUKARYOTA for achieving exchange of chromosome material during fusion of two cells. In bacteria, this is a uni-directional transfer of genetic material; in protozoa it is a bi-directional exchange. In algae and fungi, it is a form of sexual reproduction, with the union of male and female gametes.Placenta: A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES).Vagina: The genital canal in the female, extending from the UTERUS to the VULVA. (Stedman, 25th ed)Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Myometrium: The smooth muscle coat of the uterus, which forms the main mass of the organ.Mice, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.Ectoderm: The outer of the three germ layers of an embryo.Cholesterol Ester Transfer Proteins: Proteins that bind to and transfer CHOLESTEROL ESTERS between LIPOPROTEINS such as LOW-DENSITY LIPOPROTEINS and HIGH-DENSITY LIPOPROTEINS.Fertility: The capacity to conceive or to induce conception. It may refer to either the male or female.Electron Transport: The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)Dilatation: The act of dilating.Pregnancy Complications: Conditions or pathological processes associated with pregnancy. They can occur during or after pregnancy, and range from minor discomforts to serious diseases that require medical interventions. They include diseases in pregnant females, and pregnancies in females with diseases.Treatment Failure: A measure of the quality of health care by assessment of unsuccessful results of management and procedures used in combating disease, in individual cases or series.