Embryology Flashcards
What are the main stages of embryo development?
- gametogenesis
- fertilisation
- cleavage
- gastrulation
- formation/folding
- organogenesis
What is involved in gametogenesis?
germ cell formation of oocyte and spermatozoa
What is involved in fertilisation?
fusion of sperm and oocyte to make zygote which lasts for 12-24 hours
What is cleavage?
the zygote undergoes rapid cell division to form blastomeres
What is gastrulation?
formation of germ cell layers so ectoderm, mesoderm and endoderm and the body establishes axes
What is organogenesis?
organs and organ systems develop
What happened in the foetal period?
growth, tissue maturation, sex differentiation, bone, CNS connections
What are the primary processes?
cell division differentiation cell attachment apoptosis induction cell migration
What are secondary processes?
axis formation
folding/rotation
What is control of development governed by?
genetics and epigenetics
What is the site of fertilisation?
ampulla
What are the steps of fertilisation?
- sperm binds to zona pellucida glycoprotein
- acrosomal enzymes digest into egg
- egg and sperm membranes fuse and sperm contents enter egg
- egg completes meiosis 2 and there is release of cortical granules by oocyte
What is compaction?
cells coming close together with cell junctions, gap junctions form for outer cells
What does the trophoblast become?
embryonic part of placenta
What does the inner cell mass of the embryo become?
embryo, amnion and yolk sac
What happens in implantation?
- 6 days: active process by trophoblast and it divides into cut-trophoblast and synctiotrophoblast
- 7.5 days: embryo is epiblast at dorsal and hypoblast at ventral and the amniotic cavity begins to form
Where does the embryo implant?
upper or middle dorsal surface of the uterus
What is involved in gastrulation?
formation of the germ layers so epiblast cells move through the primitive streak to form he mesoderm
What does the ectoderm become?
epidermis (hair, nails, glands) and nervous system
What does the mesoderm become?
- paraxial: skeleton, voluntary muscles, dermis
- intermediate: urogenital system
- lateral somatic: lining of body walls, dermis, limb parts
- lateral visceral: cardiovascular, mesothelial covering organs, smooth muscle
What does the endoderm become?
lining of the gut tube, respiratory tract, bladder and urethra
What does cranial folding form?
foregut
