Where does follicular development occur in the ovary?

From the Guidelines

Follicular development occurs primarily in the cortex of the ovary. The ovarian cortex is the outer layer of the ovary that contains the primordial follicles, which house immature oocytes. During each menstrual cycle, several primordial follicles begin to develop under the influence of follicle-stimulating hormone (FSH) released from the anterior pituitary gland. As development progresses, these follicles grow in size and advance through various stages including primary, secondary, and antral follicles. Eventually, one dominant follicle typically emerges and continues to mature into a Graafian follicle, which will rupture during ovulation to release the mature oocyte. The cortical location of follicular development is significant because it allows the mature follicle to protrude toward the ovarian surface, facilitating ovulation when the follicle ruptures. The medulla, which is the inner region of the ovary, contains blood vessels, lymphatic vessels, and nerves that support the metabolic needs of the developing follicles but is not the site of follicular development itself.

Key points to consider:

• The cortex of the ovary is the primary site of follicular development 1.
• Follicular development is influenced by follicle-stimulating hormone (FSH) released from the anterior pituitary gland.
• The cortical location of follicular development allows for the mature follicle to protrude toward the ovarian surface, facilitating ovulation.
• The medulla of the ovary supports the metabolic needs of the developing follicles but is not the site of follicular development itself.

In terms of clinical relevance, understanding the location of follicular development is crucial for procedures such as oocyte and embryo cryopreservation, which require ovarian stimulation and follicle aspiration 1. Additionally, the number of retrieved oocytes is reduced in women with poor ovarian reserve, highlighting the importance of preserving fertility in women with cancer or other conditions that may affect ovarian function 1.

From the FDA Drug Label

Clomiphene citrate initiates a series of endocrine events culminating in a preovulatory gonadotropin surge and subsequent follicular rupture. The first endocrine event in response to a course of clomiphene therapy is an increase in the release of pituitary gonadotropins This initiates steroidogenesis and folliculogenesis, resulting in growth of the ovarian follicle and an increase in the circulating level of estradiol.

The ovarian follicle growth occurs in the ovary.

• Follicular development occurs in the ovary [@\1@]. The specific layer is not mentioned in the provided text.

From the Research

Follicular Development in the Ovary

Follicular development occurs in the ovarian cortex, specifically in the following layers:

• The outer cortex, where primordial follicles are located 2
• The inner cortex, where primary follicles are found 2
• The cortico-medullary boundary, where secondary and antral follicles are positioned 2

Key Stages of Follicular Development

The development of ovarian follicles involves several stages, including:

• Activation of primordial follicles 3
• Growth of preantral follicles 3
• Transition from primary to secondary follicle 3
• Development of secondary follicles to the periantral stage 3
• Antral follicle formation and ovulation 4, 5

Cellular Interactions and Regulation

Follicular development is regulated by interactions between:

• Oocytes and granulosa cells 4, 5
• Granulosa cells and theca cells 4, 5
• Autocrine and paracrine factors, such as growth factors and hormones 5, 3 These interactions control the growth, differentiation, and survival of follicles, ultimately leading to ovulation and corpus luteum formation 4