Embryology

Question 1

Urorectal septum grows caudally till it reaches what membrane?

Answer 1

cloacal membrane

Question 2

By which week does the anal membrane rupture?

Answer 2

week 9

Question 3

What are the 2 membranes formed after the cloaca is split?

Answer 3

urogenital and anal membrane

Question 4

What is the median umbilical ligament a remnant of?

Answer 4

remnant of the connection between urinary bladder and allantois

Question 5

What does the pelvic part of the urogenital sinus form?

Answer 5

urethra

Question 6

what is an imperforate anus?

Answer 6

Rectal fistulas are frequently observed in association with an imperforate anus (where anal membrane persists).

Question 7

What is a fistula?

Answer 7

– irregular passageways between ducts

Question 8

What are the 3 kidney systems that form in development? From what week? Which one becomes the functioning kidney?

Answer 8

Pronephros, mesonephros
-transient
Metanephros
-functional

week 4

Question 9

Which mesoderm do they form from?

Answer 9

intermediate mesoderm

Question 10

What cell clusters are formed?

Answer 10

nephrotomes

Question 11

Mesonephros produces mesonephric duct. Why is this duct important?

Answer 11

aka Wolfian duct

as the duct is where the persistent kidney comes from as an outbudding from that duct

Question 12

At which week is all this taking place? By the end of that week, what will have formed?

Answer 12

end of 4th week

metanephros

Question 13

What is the outbudding from the mesonephric duct called?

Answer 13

ureteric bud

Question 14

What germ layer is the metanephric tissue derived from?

What will the uretric bud form?

Answer 14

mesoderm

forms ureter and renal pelvis

Question 15

The Metanephric mesoderm forms what?

Where does the kidney start in development?

Answer 15

excretory units

pelvis

Question 16

why do the kidneys ascend?

Answer 16

Ascends partly due to reduced curvature of the body due to rapid proliferation in the lumbar and sacral regions

Question 17

What do germ cells have to do for the gonads to form?

Answer 17

migrate to the gonadal ridge

Question 18

Explain the pathway of germ cell migration

By what week is all this happening

Answer 18

between endodermal and lining of yolk sac, from allantois and through dorsal mesentery to reach genital ridges

week 5

Question 19

If embryo is genetically female, what will the genital ridges form?

Answer 19

oogonia

Question 20

What are the cortical cords?

Cortical cords break down to form?

Answer 20

germ cells surrounded by epithelial cells

cell clusters

Question 21

Paramesonephric duct important for?

Mesonephric duct important for

Answer 21

reproductive organs in women

for development of kidney

Question 22

What is formed when the paramesonephric ducts fuse in the midline in females??

Answer 22

form uterus, uterine tube and upper part of vagina

Question 23

Where does the lower half of the vagina come from?

Answer 23

urogenital sinus

Question 24

What happens to the mesonephric duct in females? In males?

Answer 24

degenerates

not in males

Question 25

if the embryo is genetically male:

What will the primitive sex cords form? It’s a layer of dense CT

Answer 25

testis cords

Question 26

Primitve sex cords don’t have a lumen. At what point does the lumen form?

Answer 26

puberty

Question 27

where do the gonads starts development?

Answer 27

abdomen

Question 28

What is the gubernaculum?
Where does the tunica vaginalis come from?
What are the 2 layers of the tunica vaginalis?

Answer 28

condensation of mesenchymal cells rich in ECM proteins

peritoneum

visceral and parietal layer

Question 29

what is the processus vaginalis

Answer 29

Processus vaginalis is connection that has been obliterated

Question 30

What does the transversalis fascia become continuous with?
External oblique?
Internal oblique?

Answer 30

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

Question 31

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

Answer 31

week 4

cloacal membrane

uro-rectal septum

Question 32

what grows to form the phallus?

What fuses to form the shaft? And the scrotum?

Answer 32

genital tubercle

urethra folds
scrotal swellings

Question 33

What do genital tubercles form in the female?
What do the urethral folds form?
What do genital swellings form?

Answer 33

clitoris

labium

labium majorum