Basic concepts of biology for human development. Definition
Blastocyst – after morula stage of embryogenesis, when the cells of the morula secrete fluid and form a fluid-filled cavity in which is outlined a separate group of cells — the inner cell mass (embryoblast). The remaining cells of the blastocyst (trophoblast) form the chorion, part of the placenta and shell, which from the inner cell mass the embryo develops.
The inner cell mass (embryoblast) – is a compact group of cells of the morula, forming the embryo. The embryoblast divides into epiblast (layer of cylindrical cells) and gipoblasta (layer cubic cells facing blastocele). Epiblast and gipoblasta together form the double-layered embryonic disk (blastodisk).
Gastrulation — the stage of development that begins after the implantation of the morphogenetic process in which from a single layer of epiblast the formation of three primary germ layer: endoderm, mesoderm and ectoderm; even before gastrulation of the embryo cells lose the property of totipotency, i.e. the ability to evolve in different directions.
The gipoblasta — part of the cells of the inner cell mass (primary endoderm), forming the shell of the fetus (amnion).
Determination — the stage of development at which the cell chooses one of many possible paths of development, i.e., becoming ordained to the development in a particular direction.
Monoamniotic twins — monozygotic twins resulting from the splitting of the inner cell mass (embryoblast) without separation of the inner cell mass, forming amniote-cal shell (gipoblasta).
Morphogen — a substance produced by the cells in a specific region of the embryo, extending from place of origin to the tissues of the embryo with the formation of a concentration gradient. Depending on the concentration of morphogen acting on the cage-the target, she is determined to develop a particular line of differentiation.
Multipotent stem cell — a stem cell capable of reproducing itself, and to the development of many types of cells, but not in the whole body.
Regulatory development — the stage when cells have not yet commiteeman, and removal of part of the embryo can still lead to the formation of a complete organism.
Stem cell — cells that have the potential both to generate another stem cell (self-replication) and to differentiate into specialized cells within a tissue or whole organism.
Embryo — the stage of development of the human organism from fertilization to 9 weeks of gestation, when there is a division in placental and embryonic tissue. During this period the morphogenesis of the basic structures of the body.
Embryonic stem cells — cells derived from the inner cell mass; under suitable conditions they can differentiate into all types of cells and tissues of the embryo, forming a complete embryo.
Endoderm — the primary embryonic germ layer that forms many of the visceral organs and the gut wall.