Embryonic Development Week 3

The initial stage of embryonic development characterized by a solid ball of cells.

A small, elevated region at the cranial end of the primitive streak that serves as an organizing center for notochord and axial structure formation.

The outer layer of cells in the morula that contributes to the placenta.

The inner layer of cells in the morula that forms the embryo itself.

The process where blastomeres maximize contact with each other, forming tight junctions in the outer layer of the morula.

A membrane located at the cranial end of the embryonic disc that marks the future mouth opening.

A stage in early embryonic development where the zygote undergoes multiple cell divisions to form a ball of cells.

A structure that serves as a primitive backbone during embryonic development.

Cell divisions that happen without an increase in cell size. The cells get smaller with each division.

The process of creating the mesoderm, which forms connective tissues and the cardiovascular system.

Cells that can develop into any type of cell in the body.

The area at the tail end of the embryonic disc that lacks mesoderm and will eventually form the anal membrane.

A hollow ball of cells formed during embryonic development. It is surrounded by a fluid-filled cavity called the blastocoel.

A specific cell layer inside the blastocyst.

The process by which a single-celled zygote develops into a multicellular embryo.

The outer layer of the embryo that protects and nourishes the developing embryo.

The process that transforms the bilaminar embryonic disc into a trilaminar disc, marking the transition from a single layer to three distinct germ layers.

A thickened linear band of epiblast cells on the dorsal surface of the embryonic disc, crucial for establishing the embryo's body plan.

The process of epiblast cells moving towards the primitive streak, initiating the formation of the three germ layers: ectoderm, mesoderm, and endoderm.

The innermost germ layer formed during gastrulation, giving rise to the lining of the digestive tract and respiratory system.

The middle germ layer formed during gastrulation, responsible for creating diverse structures like muscles, bones, and blood vessels.

The outermost germ layer formed during gastrulation, giving rise to the skin, nervous system, and sense organs.

The early phase of the primitive streak.

The merging of the male and female pronuclei during fertilization, restoring the diploid state after haploid gametes unite.

The glycoprotein layer surrounding the zygote, preventing premature implantation and protecting the developing embryo.

The single diploid cell formed after fertilization, containing 46 chromosomes.

The thickened region of ectoderm on the dorsal surface of the embryo, which later gives rise to the central nervous system.

The inward folding of the neural plate, forming a groove that eventually closes to form the neural tube.

The process of epiblast cells migrating through the primitive line and replacing the original hypoblast to form the innermost germ layer, the definitive endoderm.

The process where the trophoblast cells differentiate and fuse to form a multinucleated structure that secretes hCG.

The hormone secreted by the syncytiotrophoblast that maintains the corpus luteum and prevents menstruation.

The process where the trophoblast cells penetrate the uterine lining and connect to the maternal blood supply.

The process where the neural plate folds inward to form the neural tube, which eventually becomes the brain and spinal cord.

The process where the ectoderm cells invaginate to form a cavity that becomes the amniotic sac.

The spaces that precede the development of the uteroplacental circulation, which is responsible for nutrient and waste exchange between mother and fetus.

The cellular layer between the ectoderm and endoderm that gives rise to muscles, bones, blood, and many other internal structures.

The cell layer lining the blastocoel in early development. It forms the extraembryonic membrane.

A cavity filled with fluid in the blastocyst. It eventually becomes the yolk sac.

A process during which the blastocyst implants into the uterine wall.

A structure derived from the hypoblast that provides early nutrient exchange for the developing embryo.

Specialized cells that migrate and contribute to the formation of various tissues, including nerves, pigment cells, and parts of the face.

A component of the mesoderm that gives rise to the vertebrae, skeletal muscles, and skin.

A component of the mesoderm that forms the kidneys and gonads.

A component of the mesoderm that forms the heart, blood vessels, and lining of the body cavity.

The mesodermal layer that lines the cytotrophoblast and amnion (outermost embryonic membranes).

The mesodermal layer that surrounds the yolk sac.

A cavity that forms within the extraembryonic mesoderm, separating the developing embryo from the trophoblast.

A new yolk sac structure that replaces the primary yolk sac, providing nutrition and supporting blood cell formation.

These are spaces filled with maternal blood within the syncytiotrophoblast, enabling nutrient exchange between mother and embryo.