What is the Difference Between Primary Secondary and Tertiary Follicle?

The difference between primary, secondary, and tertiary follicles lies in their growth, structure, and development. Follicles are cells that enclose a cavity or other cells, and they play a crucial role in the development of ovarian follicles. Here are the key differences between the three types of follicles:

1. Primary Follicles:

• Develop from primordial follicles.
• Have a single layer of granulosa cells.
• Surround a primary oocyte.
• Small in size.

1. Secondary Follicles:

• Develop from primary follicles.
• Have multiple layers of granulosa cells.
• Surround a primary oocyte.
• Larger than primary follicles but smaller than tertiary follicles.
• Do not have a fluid-filled chamber called antrum.

1. Tertiary Follicles (Graafian Follicles):

• Develop from secondary follicles.
• Have multiple layers of granulosa cells and an antrum.
• Surround a primary oocyte that completes its first meiotic division, producing a secondary oocyte and a polar body.
• Rupture to release the secondary oocyte in a process known as ovulation.

The primary follicles develop into secondary follicles, and then into tertiary follicles. The growth of follicles is regulated by hormones, such as follicle-stimulating hormone (FSH), which influences the maturation of follicles.

Comparative Table: Primary Secondary vs Tertiary Follicle

Here is a table summarizing the differences between primary, secondary, and tertiary follicles:

• Primary Follicle: Develops from the stimulation of a primordial follicle and has a single layer of follicular cells.
• Secondary Follicle: Develops from the primary follicle and is a preantral follicle with multiple layers of granulosa cells.
• Tertiary Follicle: Develops from the secondary follicle, has a fluid-filled cavity (antrum), and is larger in size compared to primary and secondary follicles. The mitotic rate of the granulosa and theca cells begins to decline in tertiary follicles.