Development of the Repro Tract

Question 1

What is the specific order of the development of the repro tract

Answer 1

1. Establishment of chromosomal sex
2. Establishment of gonadal sex
3. Development of the internal genitalia
4. Development of the external genitalia

Question 2

Chromosome number of the horse

Answer 2

64

Question 3

Chromosome number of donkey

Answer 3

62

Question 4

Chromosome number of mules

Answer 4

63

Question 5

True or False: The number of X chromosomes determines gonadal sex.
Provide examples for either argument.

Answer 5

False
65, XXY (Equine equivalent of Klinefelter Syndrome in humans) have testes and are phenotypic males.
63, XO (Turner’s Syndrome) have primitive ovaries and are phenotypic females

Question 6

What are some genes that are responsible for male gonadal development

Answer 6

SRY gene
Sox 9
Fgf9
Pgds
Amh

Question 7

What are some genes responsible for female gonadal development

Answer 7

Absence of SRY**
Wnt4
Rspo1
Foxl2

Question 8

Fill in the blanks: The following give rise to \_\_\_\_\_\_\_\_.
Developing male sex cords -> \_\_\_\_\_\_\_\_
Primordial germ cells -> \_\_\_\_\_\_\_\_
Supporting cells -> \_\_\_\_\_\_\_\_
Tissue between cords -> \_\_\_\_\_\_\_\_

Answer 8

Developing male sex cords -> Seminiferous tubules
Primordial germ cells -> Spermatozoa
Supporting cells -> Sertoli cells
Tissue between cords -> Leydig cells

Question 9

Fill in the blanks: The following give rise to \_\_\_\_\_\_\_\_.
Developing female sex cords -> \_\_\_\_\_\_\_\_
Primordial germ cells -> \_\_\_\_\_\_\_\_
Supporting cells -> \_\_\_\_\_\_\_\_
Interstitial cells -> \_\_\_\_\_\_\_\_

Answer 9

Developing female sex cords -> spherical structures, ultimately follicles in cortex
Primordial germ cells -> oocytes
Supporting cells -> Granulosa cells
Interstitial cells -> Theca cells

Question 10

The Mullerian duct will develop into the _______

Answer 10

oviduct, uterus, cervix, and cranial vagina

Question 11

The Wolffian duct will develop into the _________

Answer 11

Epididymis
Vas deferens
Urethra

Question 12

What hormone results in regression of the Mullerian ducts?

Answer 12

AMH

Question 13

Where is AMH produced in the testicle?

Answer 13

Sertoli cells

also produce inhibin

Question 14

What hormone stimulates the development of Wolffian ducts?

Answer 14

Testosterone

Question 15

What cells produce testosterone in the testicle?

Answer 15

Leydig cells

Question 16

Masculinization is caused by _________

Answer 16

Dihydrotestosterone

Question 17

Testosterone is converted to DHT via what enzyme?

Answer 17

5alpha reductase

Question 18

DHT directs formation of the _____ external genitalia including the _____ and _______

Answer 18

male, penis, scrotum

Question 19

Name 3 clinical uses of AMH concentration in adult horses

Answer 19

Diagnostic test for presence of testicular tissue
Diagnostic test for presence of granulosa cell tumor
Estim

Question 20

True or False: A horse fetus undergoes marked hypertrophy of the fetal gonad mid gestation.

Answer 20

True

Question 21

When does gonadal hypertrophy of the equine fetus peak

Answer 21

~ 7 months

Testosterone in pregnant mares will peak around 200-210 days gestation

Question 22

When does the testicular descent occur in the horse?

Answer 22

Between 30 days before and 10 days after birth.