Ovarian Follicular Development

Ovarian follicular development beings start when the female fetus is in her uterus. during the fifth stage of the pregnancy, a female fetus’s ovary contains about 500 to 1300 primordial germs cells. The primordial germ cell undergoes mitosis, and in the twentieth week of pregnancy, the female fetus has approximately 6 to 7 million germ cells. once the mitosis cell is complete, the germ cells are in the meiosis stage and arrest in the meiotic prophase1, forming germ cell cysts.

Stages of Follicle Development in the ovary

Follicular development is divided into three stages

• Activation of primordial follicles
• The primary to secondary follicle transition 
• The development of secondary follicles to the pericentral stage.

Primordial Follicle Formation

In humans, the primordial follicles are formed in the fetal ovaries between the sixth and ninth months of gestation. At this time, it is believed that all viable female germ cells have committed to meiosis. As a result, by the end of gestation, there is no further production of new oocytes.

How is a primordial follicle formed-The formation of primordial follicles occurs when germ cell nests break apart and individual oocytes become surrounded by pregranulosa cells.

Primary Follicle Development

When the primordial follicle is stimulated, it becomes a primary follicle. The oocyte enlarges, and the follicular cells divide. A follicle that has two layers of follicular cells is called a primary follicle. These cells continue to hypertrophy and proliferate to form many layers surrounding the oocyte. There are some hormones that develop the primary follicle development GnRHstimulates (causes) the pituitary gland to produce follicle-stimulating hormones (FSH) the hormone responsible for the starting follicle (egg) development and causing the level of estrogen (the primary female hormone) to rise. 

Pre-antral Follicle 

Pre-antral follicles are those follicles that are primordial, primary, or secondary, whereas antral follicles are either tertiary or ovulatory also called graafian follicles. Primordial follicles can be defined as nongrowing, with all other types being committed to growth, differentiation, and ovulation or to atresia.

Pre-antral follicle development- Pre-antral follicular development can be divided into three stages: activation of primordial follicles, the primary to secondary follicle transition, and the development of secondary follicles to the preantral stage.

Antral follicle development

Antral follicles begin producing increasing levels of progestins, estrogens, and androgens. The mural granulosa cells and the adjacent theca cells surrounding. antral follicles are formed when the formation of the antrum also requires the movement of granulosa cells relative to each other to allow the fluid to accumulate. this presumably involves the remodeling of cell-cell junctions and species with small follicles may involve the death of centrally located granulosa cells.

The ovary has mainly two functions. firstly, the ovary produces hormones that drive the female reproductive system. the second one is it controls the development and the selection of mature oocytes for fertilization. This process known as ovarian folliculogenesis begins while the female is in-utero. and in simple language One of the pair of female glands in which the eggs form and the female hormones estrogen and progesterone are made. these hormones play an important role in female traits, such as breast development, body shape, and body hair.  

• The Role of the ovary- The role of ovary, ovaries are in small size, oval-shaped glands locate on either side of your uterus. They produce and store your eggs (also called an ovum) and make the hormones that control your menstrual cycle and pregnancy. during ovulation time, one of your releases an egg. if sperm are also fertilized then the egg can become pregnant.
• Importance of the ovary – Your ovary plays the main role in menstruation and Conception. They produce eggs for fertilization and they will make the hormones estrogen and progesterone. . An ovary releases an egg around the middle of your menstrual cycle (around day 14 of a 28-day cycle) in a process called ovulation.