Early embryology + the gut tube Flashcards
Which tissue layer surrounds the fertilised ovum as it undergoes mitotic divisions?
Zona pellucida
After several mitotic divisions, the fertilised egg becomes what?
Morula
What does the zona pellucida prevent?
Polyspermy
The morula becomes what?
Blastocyst
What are the 2 cell layers of the blastocyst?
Trophoblast
Embryoblast
On which day does the blastocyst form?
Day 5
On which day does the blastocyst begin to implant into the endometrium?
Day 8
As the blastocyst implants into the endometrium, which new and invasive cell layer helps with this?
Syncytiotrophoblast
What cell layers comprise the bilaminar disc?
Epiblast
Hypoblast
What space is above the epiblast?
Amniotic cavity
What space is below the hypoblast?
Yolk sac
Which day does the chorionic cavity appear?
Day 13
The connecting stalk eventually becomes what?
Umbilical cord
What is gastrulation?
Rapid division and downwards migration of epiblast cells to create a 3 layered trilaminar embryonic disc
What are the layers of the trilaminar disc?
Ectoderm
Mesoderm
Endoderm
What is the area called where the cells of the bilaminar disc migrate downwards to form the trilaminar disc?
Primitive groove
Cells of the primitive pit / node form what?
Notochord
If the primitive node and primitive streak do not disappear, what can this lead to the formation of?
Teratoma
A teratoma can form if which structures do not disappear?
Primitive node and primitive streak
The notochord eventually becomes which structure?
Nucleus pulposus of the IV discs in spine
What are the 3 sections of mesoderm, moving from medial to lateral?
Paraxial
Intermediate
Lateral plate
Which section of mesoderm forms the urogenital system?
Intermediate mesoderm
The epidermis is derived from which trilaminar disc layer?
Ectoderm
The dermis is derived from which trilaminar disc structure?
Mesodermal somites
Lateral folding of the embryonic disc begins on which day?
Day 18
What angle does the gut tube rotate as it develops and around which axis?
270 degrees anticlockwise around the SMA
What are 2 conditions where the gut tube remains herniating through the umbilicus after birth?
Omphalocele
Gastroschisis
