Lecture 13 - Internal Development

Question 1

What gene is on the “Y” chromosome that is known as the “Sex-determining Region of Y”?

Answer 1

SRY is the gene that is known as the Sex-determining region of Y. If you have SRY gene, you have testicles. Bc XY=male

Question 2

On the ends of X-Chromosome are regions known as “pseudo-autosomal” what genes are involved in this region?

Answer 2

Pseudo-autosomal region are genes involved in bone formation → height

Question 3

People have two X chromosomes (normal female→ XX or rare male→ XXY) but one of the X chromosomes will get MOSTLY shut off. Which region still remains active and the genes from this area will still get transcribed?

Answer 3

Pseudo-autosomal regions. They are dose dependent.

Question 4

Klinefelter syndrome→ when an individual has XXY genotype. This leads to all sorts of things like

• DAX-1 leads to not enough gonads (small gonads/ small testes)
• Increased height
• Altered fertility aka usually infertile

What happens to hormones?

Answer 4

1. Less testosterone production and more FSH and LH production.
2. Leydig cells don’t function properly. Leydig cells hit harder than Sertoli cells. As a result, more estradiol than testosterone.

Question 5

Tuner syndrome→ XO genotype (only one x chromosome, no secondary chromosome).

What are their characteristics?

Answer 5

• Short
• Chest abnormalities
• Infertile
• Ovaries are nonexistent

Question 6

Internal structures in Males and Females

Answer 6

• Male internal reproductive structures: Epididymis/vas deferens/seminal vesicles
• Female internal reproductive structures: oviduct/uterus/cervix

Question 7

External reproductive systems in Males and Females

Answer 7

• External reproductive system in males: penis/scrotum
• External reproductive system in females: vagina/clitoris/labia

Question 8

Development of Male reproductive system…

Answer 8

• Y choromosome has the SRY gene
• Testerone tells Wolffian ducts to develop into male reproductive system
• Sertoli cells make “anti-mullerian hormone” to get rid of the female reproductive system

Question 9

Development of female reproductive system

Answer 9

• Mullerian ducts don’t need a signal, they will always stick around unless told to leave
• Wolferian ducts (male reproductive system) degenerate