Lecture 5 - Embryology Reproductive System 1

Question 1

What is gastrulation

Answer 1

early phase of embryonic development - single layered blastula

Question 2

what happens during gastrulation

Answer 2

cranial/caudal and right/left axes of the embryo are established

Question 3

What is the genetic sex determined by

Answer 3

the sperm

Question 4

What does the Sex-determining region of the Y chromosome do?

Answer 4

gene initiates production of testis-determining factor (TDF)

no Y chromosome - no TDF - female

Question 5

what is the reproductive system derived from?

Answer 5

intermediate mesoderm-urogential ridge - urinary system and reproductive system

Question 6

5-6 weeks

Answer 6

epithelium proliferates and penetrates underlying mesoderm to form primitive sex cords
male and female are indistinguishable (indifferent gonad)

Question 7

week 6

Answer 7

primordial germ cells migrate to genital ridge

Question 8

indifferent gonad parts

Answer 8

primitive sex cords will detach from the cortex to form the medullary cords

Question 9

What is fate of medullary and cortical regions dependent on

Answer 9

testis -determining factor

Question 10

Difference between embryonic structures in male and female development

Answer 10

Female - cortical cords develop, medullary cords - regress and tunica albuginea - no development
Male - tunica albuginea and medullary cords develop
cortical cords - regress

Question 11

Medullary (testis) cords form

Answer 11

Rete testis, seminiferous tubules

Question 12

Development of the ovary

Answer 12

medullary cords degenerate
surface epithelium continues to proliferate and produce second generation of cords - cortical cords
cortical cords split and surround oocytes

Question 13

When do gonads become distinguishable?

Answer 13

7 weeks

develop on posterior abdominal wall

Question 14

how does the testes descend

Answer 14

extraabdominal gubernaculum shortens, pulling testes towards the anterior abdominal wall (wk7-12)
testes arrive at internal inguinal ring
remain here from 3rd to 7th month

after 7 months - gubernaculum shortens again - pulls it through the internal inguinal canal
-aided pressure from ab organs
testes- reaches scrotum by 9th month just before birth

Question 15

what obliterates within the 1st year ?

Answer 15

processus vaginalis - giving tunica vaginalis - remnant around testis

Question 16

what is the processus vaginalis derived from?

Answer 16

peritoneum

Question 17

Deep ring

Answer 17

entrance of inguinal canal and located in transversalis fascia

Question 18

Superficial ring

Answer 18

exit of inguinal canal and is located in external oblique

Question 19

Internal spermatic fascia derived from

Answer 19

transversalis fascia

Question 20

cremasteric fascia derived from

Answer 20

internal oblique muscle

Question 21

External spermatic fascia

Answer 21

external oblique muscle

Question 22

What can happen with a patent processus vaginalis

Answer 22

parts of processus vaginalis may remain unfused - leave small cysts
cysts can produce fluid and swell - hydrocele
if open to abdominal cavity, intestines may protrude through inguinal canal - indirect inguinal hernia

Question 23

Hydrocele transillumination

Answer 23

formed by clear fluid, therefore light passes through easily
tissue or tumour - block light
hydrocele - benign but may cause discomfort
-can be removed surgically

Question 24

cryptorchidism

Answer 24

failure of both or single testis to descent
affects 1-4% - most correct by 2 months
remain undescended - corrected surgically at 4-6 months
associated with increased risk of testicular cancer and infertility

Question 25

descent of ovaries

Answer 25

descend to pelvic brim

gubernaculum passes through inguinal canal and inserts onto labia majora

Question 26

what does the gubernaculum persist in adult as

Answer 26

persists in adult as ovarian ligament proper and round ligament of the uterus