Blastocyst Inner Cell Mass: The cluster of cells inside a blastocyst. These cells give rise to the embryonic disc and eventual embryo proper. They are pluripotent EMBRYONIC STEM CELLS capable of yielding many but not all cell types in a developing organism.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.Embryonic Development: Morphological and physiological development of EMBRYOS.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.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.Trophoblasts: Cells lining the outside of the BLASTOCYST. After binding to the ENDOMETRIUM, trophoblasts develop into two distinct layers, an inner layer of mononuclear cytotrophoblasts and an outer layer of continuous multinuclear cytoplasm, the syncytiotrophoblasts, which form the early fetal-maternal interface (PLACENTA).Embryonic and Fetal Development: Morphological and physiological development of EMBRYOS or FETUSES.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.Embryo Implantation: Endometrial implantation of EMBRYO, MAMMALIAN at the BLASTOCYST stage.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.Octamer Transcription Factor-3: An octamer transcription factor that is expressed primarily in totipotent embryonic STEM CELLS and GERM CELLS and is down-regulated during CELL DIFFERENTIATION.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.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.Fertilization in Vitro: An assisted reproductive technique that includes the direct handling and manipulation of oocytes and sperm to achieve fertilization in vitro.Endoderm: The inner of the three germ layers of an embryo.Ectoderm: The outer of the three germ layers of an embryo.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Zygote: The fertilized OVUM resulting from the fusion of a male and a female gamete.Chimera: An individual that contains cell populations derived from different zygotes.Embryonic Stem Cells: Cells derived from the BLASTOCYST INNER CELL MASS which forms before implantation in the uterine wall. They retain the ability to divide, proliferate and provide progenitor cells that can differentiate into specialized cells.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.Ectogenesis: Embryonic and fetal development that takes place in an artificial environment in vitro.Germ Layers: The three primary germinal layers (ECTODERM; ENDODERM; and MESODERM) developed during GASTRULATION that provide tissues and body plan of a mature organism. They derive from two early layers, hypoblast and epiblast.Parthenogenesis: A unisexual reproduction without the fusion of a male and a female gamete (FERTILIZATION). In parthenogenesis, an individual is formed from an unfertilized OVUM that did not complete MEIOSIS. Parthenogenesis occurs in nature and can be artificially induced.Nuclear Transfer Techniques: Methods of implanting a CELL NUCLEUS from a donor cell into an enucleated acceptor cell.GATA6 Transcription Factor: A GATA transcription factor that is expressed predominately in SMOOTH MUSCLE CELLS and regulates vascular smooth muscle CELL DIFFERENTIATION.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.Embryo Implantation, Delayed: Delay in the attachment and implantation of BLASTOCYST to the uterine ENDOMETRIUM. The blastocyst remains unattached beyond the normal duration thus delaying embryonic development.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.Cell Lineage: The developmental history of specific differentiated cell types as traced back to the original STEM CELLS in the embryo.Cell Count: The number of CELLS of a specific kind, usually measured per unit volume or area of sample.Ear, Inner: The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.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).Totipotent Stem Cells: Single cells that have the potential to form an entire organism. They have the capacity to specialize into extraembryonic membranes and tissues, the embryo, and all postembryonic tissues and organs. (Stem Cells: A Primer [Internet]. Bethesda (MD): National Institutes of Health (US); 2000 May [cited 2002 Apr 5]. Available from: http://www.nih.gov/news/stemcell/primer.htm)Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.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.HMGB Proteins: A family of sequence-related proteins similar to HMGB1 PROTEIN that contains specific HMG-BOX DOMAINS.Fibroblast Growth Factor 4: A HEPARIN binding fibroblast growth factor that may play a role in LIMB BUDS development.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.Pluripotent Stem Cells: Cells that can give rise to cells of the three different GERM LAYERS.Zona Pellucida: A tough transparent membrane surrounding the OVUM. It is penetrated by the sperm during FERTILIZATION.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.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.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.SOXF Transcription Factors: A subclass of closely-related SOX transcription factors. Members of this subclass are expressed in VASCULAR ENDOTHELIAL CELLS and may play a role in vasculogenesis.Mice, Inbred CBACell Aggregation: The phenomenon by which dissociated cells intermixed in vitro tend to group themselves with cells of their own type.