What is the Difference Between Primordial Follicle and Primary Follicle?

The main difference between primordial follicles and primary follicles lies in their structure and stage of development. Here are the key differences:

• Primordial Follicles:
• These are oocytes surrounded by less differentiated squamous granulosa cells.
• They are considered the starting point or 'sleeping' stage.
• Primordial follicles are so small that they are invisible to the naked eye.
• They are present in the ovaries of baby girls and persist throughout a woman's reproductive life.
• Primary Follicles:
• These are oocytes surrounded by a single layer of cuboidal granulosa cells that have initiated follicle development.
• Primary follicles are defined by the presence of one or more cuboidal granulosa cells arranged in a single layer surrounding the oocyte.
• The oocyte in a primary follicle enlarges, and the follicular cells divide.
• Primary follicles represent the next stage after primordial follicles in the process of folliculogenesis.

In summary, primordial follicles are the dormant, undeveloped follicles, while primary follicles have initiated development and are surrounded by a single layer of cuboidal granulosa cells.

Comparative Table: Primordial Follicle vs Primary Follicle

Primordial follicles and primary follicles are two stages in the development of ovarian follicles. Here is a table outlining the differences between them:

Primordial follicles are the starting point of folliculogenesis and are present in the ovaries of baby girls. They are small and remain dormant until puberty. On the other hand, primary follicles are formed from primordial follicles after the onset of puberty. They have an enlarged oocyte, which is arrested in the prophase of the first meiotic division, and a single layer of columnar granulosa cells. The primary follicle also has a zona pellucida, a homogenous membrane between the granulosa cells and oocyte.