Sexual Differentiation

Question 1

Role of Retinoic Acid in development

Answer 1

Establishes an Ant-Pos gradient to regulate Hox Gene expression

Question 2

HOX genes types

Answer 2

3’: expressed inr esponse to retinoic acid; Control anterior regions of the body

5’: expressed in response to FGF, and control Posterior development

Question 3

When does sexual differentiation occur in fetus?

Answer 3

4th - 12th week

Question 4

Where do reproductive organs originate from?

Answer 4

Germ cells f/ that yolk sac that migrate to genital ridge and interact w/ coelomic epithelium

Question 5

What are the fates of:

• Germ Cells
• Coelomic epithelium
• Mesenchymal cells

Answer 5

• Germ: Spermatagonia OR Oogonia
• Coelomic Epi: Sertoli Cells OR Granulosa cells
• Mes: Leydoig Cells OR Theca cells

Question 6

What do Sertoli Cells produce, and what does it do?

Answer 6

Anti-mullerian hormones -> inhibits mullerian duct formation

Question 7

What is the role of 5a-reductase?

Answer 7

Converts T into DHT for proper development of prostate + external genitalia

Question 8

What is H-Y, and what is its significance?

Answer 8

Histocombatability antigen on Y chromosome

Causes high rejection rate of male donor transplant by female recipient

Question 9

What is TDF?

Answer 9

SRY protein (another name)

Question 10

Role of Cells of Leydig

Answer 10

Produce Testosterone, in response to hCG, (T)which is required for wolffian duct formation into internal male genitalia

Question 11

Turner Syndrome

• Genetics
• S/S
• Morph

Answer 11

• G: Only one X
• S/S: Sexual immaturity, priamry amenorrhea, infertiity, short, webbed neck, CV + Renal abnomalities
• Morph: “Streak” Ovaries; atrophy

Question 12

Androgen Insensitivity Syndromes

• Genetics
• Path
• S/S

Answer 12

• X-linked
• Path: Androgen receptor is absent or non-functioning -> external female characteristics, but internal testes
• S/S: Amenorrhea, Absent Uterus/Cervix

Question 13

Aromatase

Answer 13

Converts T -> Estradiol

Question 14

5-a-reductase Deficiency

Answer 14

• Baby may look externally female at birth if there is complete lack of DHT during development
• Testosterone levels rise during puberty causing masculine characteristics to appear, breasts fail to develop, and internal exam will reveal testes & other male structures

Question 15

Hypospadias

Answer 15

Failure of complete fusion of the genital folds resulting in a congenital opening of the urethra on the undersurface of the penis

Question 16

Kleinfelter’s Syndrome

• Genetics
• S/S

Answer 16

• XXY

- S/s: Testicular atrophy, Tall stature, feminized physique, impaired IQ

Question 17

Prader Stages

Answer 17

External Genitalia Range

Female -> Stage I-5 -> Male

Question 18

Congenital Adrenal Hyperplasia Pathology

Answer 18

The lack of feedback inhibition due to defective production of cortisolleads to high levels of adrenal androgensthat are converted to DHT causing masculinization of a female fetus