Bio - Embryogenesis and Development

Zygote

newly formed diploid zygote upon fertilization, defining characteristic is unicellularity

Embryo

cleavage of zygote

Morula

embryo becomes solid mass of cells after several rounds of divisions

Blastula

morula that undergoes blastulation, hollow ball of cells with fluid-filled interior known as blastocoel

Implantation

when blastula burrows into endometrium, trophoblast cells create interface between maternal blood supply and developing embryo and form chorionic villi that penetrate endometrium

Yolk sac

site of early blood cell development, supports embryo until placental formation

Allantois

early fluid exchange between embryo and yolk sac

Amnion

thin, tough membrane filled with amniotic fluid as a shock absorber during pregnancy

Gastrulation

generation of 3 distinct layers

Ectoderm

outermost layer, gives rise to integument (including epidermis, hair, nails, and epithelia of nose, mouth, and lower anal canal), lens of the eye, nervous system (including adrenal medulla), inner ear