W10- Lecture 51- Embryonic development of the respiratory system (Part 1)) Flashcards
what cell quantity do the cells become pluripotent stem cells?
time frame
16 cell stage aka morula
end of day three
what does the blastocyst consist of at day three ?
what do these develop into
outer layer of cells, the trophoblast, and an inner cell mass.
The trophoblast cells eventually give rise to the fetal placenta, whilst the inner cell mass eventually develops into the embryo
day 6 at implantation describe the structure of the embryo
inner cell mass orientated to the uterine endometrium. The endrometrial gland enlarge and the endometrium, now known as the decidua becomes more heavily vascularised
name the two distinct layers produced on day 8
what do these form together
1) The hypoblast or primative endoderm
2) The epiblast, or the primative ectoderm.
Hypoblast and the epiblast together form the bilaminer embryonic disc, and within the epiblast of this disc forms a small cavity, the amnion.
describe embryonic development once it is implanted around day 9
Amnion eventually extends and surrounds the entire embryo forming the embryonic cavity.
At around the same time cells of the hypoblast migrate and flatten forming the exocoelomic membrane around the inner surface of the blastocyst this by day 9 along with the hypoblast form the walls of the egg sac.
At this point embryonic positioned between amniotic cavity and yolk sac. Cells in the yolk sac develop into the gonad and also the yolk sac in week 4 develops into parts of the GI tract.
what are each of the germ layers and what do they form
The ectoderm gives rise to the skin and the nervous system
The mesoderm gives rise to muscle and bone
The endoderm gives rise to the epithelial lining of the GI tract and many organs
all together at this point trilaminar structure
at what day does Gastrulation take place ?
day 15 with migration of cells from epiblast forming the primative streak.
The primative streak - groove on the dorsal surface of the epiblast that that extends from the posterior (tail region) to the anterior (node) region of the bilaminar disk.
during week 4 where do the lung buds or respiratory diverticulum grow from ?
the ventral wall of the foregut
how does the lung bud become separated from the foregut ?
what else happens with this structure
but as it extends it becomes separated from foregut by, the oesophagotracheal ridges.
(cut )
These fuse to form the oesophagotracheal septum, this then divides the foregut into a dorsal region, the oesophagus, and a ventral region, the trachea.
The association between oesophagus and trachea maintained within the laryngopharynx.
