Lower GIT + Urinary organ development

Question 1

Hind gut

Answer 1

Gives off diverticulum (Allantois)

Allantois ends as:
-endodermal blind sac (Cloaca)

Cloaca is:
- in contact w/ ectodermal invagination (proctodeum)

Question 2

Cloaca (endodermal blind sac)

Answer 2

Is ➗ by Urorectal Septum into:

• Anterior part = forms Primitive bladder + Urogenital sinus
• Posterior part = forms Rectum + Upper half of anal canal

Question 3

Lower half of Anal Canal*

Answer 3

formed by Ectoderm of proctodeum

Question 4

Primitive Bladder

Answer 4

➗into:

• Upper dilated portion = Bladder
• Lower narrow portion = Urethra

Question 5

Mesonephric (Wolffian Duct)

Answer 5

gives:

- Ureteric bud: in both genders    gives rise to 
   • ureters 
   • renal pelvis 
   • minor + major calyces 
   • collecting tubules 

- In Males: gives rise to 
   • epididymal duct
   • vas deferens 
   • ejaculatory duct 
   • seminal vesicles

• In females: degenerates mostly but remnants
  • duct of epoophoron (Gärtner)
  • duct of paroophoron

Question 6

Urethra

Answer 6

develops from 2 structures:

• mesonephric duct
• Urogenital sinus

Diff parts of urethra develop from different structures in both genders

Question 7

Urethra in males + females

Answer 7

Mesonephric duct =

• Males: proximal part of prostatic urethra
• Females: upper part of urethra

Urogenital sinus =
- Males: distal part of prostatic urethra
+ penile urethra

• Females: lower end of urethra