Lecture 2 - Embryology of Repro System

Question 1

What influences the male sex of an embryo?

Answer 1

SRY gene

Question 2

What is the cloaca?

Answer 2

A part of the urogenital system, it is the common chamber and outlet into which the intestinal, urinary, and genital tracts open.

Question 3

What are PGC’s?

Answer 3

Primordial germ cells (PGCs) are germline stem cells that give rise to gametes in vertebrates. They originate outside the embryo very early in development and migrate by a well-defined route into the genital ridges.

Question 4

Coelomic epithelium refers to the epithelium that lines the surface of the body wall and the abdominal organs. Composes the outermost layer of the male and female gonads True/false?

Answer 4

True

Question 5

How are the genital ridges formed?

Answer 5

Coelomic epithelium proliferates and thickens to form genital ridges

Question 6

What is the coronal rump length (CRL)?

Answer 6

The length of the foetus from head to “rump”. Is used to mark an accurate estimation of gestational age.

Question 7

What is the abisexual (sexual indifference) stage?

Answer 7

Although genetic sex (XX or XY) is determined at fertilization, the embryos gender is not distinguishable for the first six weeks of development; this is known as the indifferent period of development.

Question 8

Sexual differentiation occurs from week 12 onwards. True/false?

Answer 8

False

Occurs from week 7 onwards

Question 9

What does the female gonad form?

Answer 9

Primordial follicles and thecal cells responsible for production of estrogens, estrone, estradiol, and estriol in the follicular phase of the menstrual cycle.

Question 10

The formation of the female external genitalia and paromesonephric ducts are influenced by what?

Answer 10

Oestrogens

Question 11

The paromesonephric (mullerian) ducts give rise to?

Answer 11

Uterine tubes
Uterus
Superior vagina

Question 12

For male development what do somatic support cells develop into?

Answer 12

Sertoli cells

Question 13

What protein stimulates formation of Sertoli cells?

Answer 13

SRY protein

Question 14

How do Sertoli cells (produced by the SRY protein) influence male sex of embryo?

Answer 14

Sertoli cells secrete (anti-Mullerian hormone) resulting in the degeneration of the paramesonephric duct (forms the uterine tubes and uterus).

As a result of this the embryo becomes male

Question 15

How are leydig cells formed?

Answer 15

Sertoli cells stimulate gonadal ridge cells

Question 16

Function of leydig cells?

Answer 16

Secrete testosterone

Question 17

During embryo formation, what does testosterone induce?

Answer 17

Formation of epididymis, vas deferens and seminal vesicles

Question 18

What induces male specific external genitalia development and prostate?

Answer 18

Dihydrotestosterone (DHT)

Question 19

What is persistent Müllerian duct syndrome?

Answer 19

Mullerian (paramesonephric) ducts fail to regress

Presents with:
Uterus, vagina and uterine tubes
Testes in ovarian location
Male external genitalia

Question 20

What is cryptorchidism?

Answer 20

Failure of one or both testes to descend

Question 21

When the mesonephric duct regresses in males, what does it form instead?

Answer 21

Seminal vesicle

Question 22

What are hypospadias?

Answer 22

External urethral opening lies in abnormal position along ventral aspect of newborn.

Can occur with varying degrees of severity