02-01 - Differentiaton of the Ovary

Question 1

(Differentiation of the Ovary)

1. In the female embryo, cords of what colonize the central part of the presumptive gonad?

Pushing what to the periphery (cortex)?

2. What happens to germ cells remaining in the central region?
3. Then the cells in the cortex do what?
4. Somatic cell lineages, including the supporting cells (pre-granulosa cells) which are thought to be from the mesonephros… do what?

Answer 1

1. mesonephric tissue

germ cells

2. degenerate
3. multiply, differentiate, and establish cortical dominance (with clusters (nests) of germ cells (oogonia at this point)
4. proliferate

(up to this point even if there are no germ cells the somatic cells of the ovary develop normally)

Question 2

(Differentiation of the Ovary - PArt 2)

1. The germ cells enter meiosis fairly synchrously in a wave from where to where?
2. These oocytes now induce the supporting cells (pre-granulosa) to differentiate as what rather thatn what?
3. The oocyte surrounded by its granulosa cells is now a what?

The time when actual follicles form depends on the species specific time when the oocytes reach what stage?

4. So follicle formation (and thus normal ovarian structure) is dependent on the presence of what?

Answer 2

1. anterior to posterior (becoming oocytes and these cells within clusters now move apart)
2. granulosa cells rather than Sertoli cells
3. follicle

the first dipoltene stage of first meiotic prophase (This may occur during fetal life or post natally, but in most species ovarian follicels form after birth)

4. the presence of germ cells

(and as we’ll see later the follicles are required for ovarian steroidogenesis - so no germ cells means no ovarian hormones)

Question 3

(Differentiation of the Ovary - Part III)

1. Now that the early follicle is formed, the supporting cells (granulosa cells) do what?
2. In the absence of this supporting action the oocytes do what?
3. What cooperates with what to suppress the male pathway?

Answer 3

1. maintain the structure and prevent formation of male gonadal features
2. undergo apoptosis (without oocytes the follicle strucutre degenerates and again a streak gonad forms)

(so you can get a streak gonad either by never having germ cells in the ovary or by losing them early in development)

3. RSPO1 and Wnt4 (suppress Fgf9 and Sox9)

Question 4

(Differentiation of the Ovary - Part IV)

1. in the developing ovary… is there a myoid precursor invasion as seen in the testicle?
2. and the supporting follicular (granulosa cells) are eventually in direct contact with what?

Answer 4

1. no
2. steroid secreting Theca cells