Embryology Flashcards
Urorectal septum grows caudally till it reaches what membrane?
cloacal membrane
By which week does the anal membrane rupture?
week 9
What are the 2 membranes formed after the cloaca is split?
urogenital and anal membrane
What is the median umbilical ligament a remnant of?
remnant of the connection between urinary bladder and allantois
What does the pelvic part of the urogenital sinus form?
urethra
what is an imperforate anus?
Rectal fistulas are frequently observed in association with an imperforate anus (where anal membrane persists).
What is a fistula?
– irregular passageways between ducts
What are the 3 kidney systems that form in development? From what week? Which one becomes the functioning kidney?
Pronephros, mesonephros
-transient
Metanephros
-functional
week 4
Which mesoderm do they form from?
intermediate mesoderm
What cell clusters are formed?
nephrotomes
Mesonephros produces mesonephric duct. Why is this duct important?
aka Wolfian duct
as the duct is where the persistent kidney comes from as an outbudding from that duct
At which week is all this taking place? By the end of that week, what will have formed?
end of 4th week
metanephros
What is the outbudding from the mesonephric duct called?
ureteric bud
What germ layer is the metanephric tissue derived from?
What will the uretric bud form?
mesoderm
forms ureter and renal pelvis
The Metanephric mesoderm forms what?
Where does the kidney start in development?
excretory units
pelvis
why do the kidneys ascend?
Ascends partly due to reduced curvature of the body due to rapid proliferation in the lumbar and sacral regions
What do germ cells have to do for the gonads to form?
migrate to the gonadal ridge
Explain the pathway of germ cell migration
By what week is all this happening
between endodermal and lining of yolk sac, from allantois and through dorsal mesentery to reach genital ridges
week 5
If embryo is genetically female, what will the genital ridges form?
oogonia
What are the cortical cords?
Cortical cords break down to form?
germ cells surrounded by epithelial cells
cell clusters
Paramesonephric duct important for?
Mesonephric duct important for
reproductive organs in women
for development of kidney
What is formed when the paramesonephric ducts fuse in the midline in females??
form uterus, uterine tube and upper part of vagina
Where does the lower half of the vagina come from?
urogenital sinus
What happens to the mesonephric duct in females? In males?
degenerates
not in males
if the embryo is genetically male:
What will the primitive sex cords form? It’s a layer of dense CT
testis cords
Primitve sex cords don’t have a lumen. At what point does the lumen form?
puberty
where do the gonads starts development?
abdomen
What is the gubernaculum?
Where does the tunica vaginalis come from?
What are the 2 layers of the tunica vaginalis?
condensation of mesenchymal cells rich in ECM proteins
peritoneum
visceral and parietal layer
what is the processus vaginalis
Processus vaginalis is connection that has been obliterated
What does the transversalis fascia become continuous with?
External oblique?
Internal oblique?
becomes continuous with internal spermatic fascia
External oblique muscle becomes continuous with the external spermatic fascia
Internal oblique muscle (in purple) becomes continuous with the cremasteric fascia
at what week do the external genitalia start to form?
What is the membrane covering it?
What divides the folds into urethral folds and anal folds
week 4
cloacal membrane
uro-rectal septum
what grows to form the phallus?
What fuses to form the shaft? And the scrotum?
genital tubercle
urethra folds
scrotal swellings
What do genital tubercles form in the female?
What do the urethral folds form?
What do genital swellings form?
clitoris
labium
labium majorum
