The Ovary
The ovaries are female gonads responsible for oogenesis and the production of sex hormones (estrogen and progesterone). Structurally, they consist of an outer cortex (containing follicles) and an inner medulla (containing vessels and nerves).
Follicular Development
| Follicle Stage | Key Features |
|---|---|
| Primordial | Oocyte surrounded by a single layer of squamous follicular cells. |
| Primary | Oocyte with cuboidal follicular (granulosa) cells. |
| Secondary/Antral | Formation of the antrum (fluid-filled space). |
| Graafian (Mature) | Large, dominant follicle ready for ovulation. |
Key Regulatory Cells
- Theca Interna Cells: Produce androgens (in response to LH).
- Granulosa Cells: Convert androgens to estrogens via the enzyme aromatase (in response to FSH).
- Corpus Luteum: Post-ovulation structure formed by granulosa and theca cells; secretes high levels of progesterone to maintain pregnancy.
High-Yield Exam Pearl:
The two-cell, two-gonadotropin theory states that LH acts on theca cells to produce androgens, which then diffuse into neighboring granulosa cells, where FSH stimulates aromatase to convert them into estrogens (estradiol).