primary ovarian follicle

folliculus ovaricus primarius

An ovarian follicle that has one layer of granulosa cells.

Type Organ
Parent Structure ovarian follicle
Latin Name folliculus ovaricus primarius
FMA ID 18634

Frequently Asked Questions

What defines a primary ovarian follicle?
A primary ovarian follicle is characterized by a primary oocyte surrounded by a single complete layer of cuboidal granulosa cells (distinguishing it from the flattened cells of the primordial stage). The zona pellucida — a glycoprotein coat around the oocyte — begins to form at this stage.
How does the primary follicle differ from primordial and secondary follicles?
Primordial follicles have a primary oocyte surrounded by a single layer of flattened pre-granulosa cells. Primary follicles have one complete layer of cuboidal granulosa cells. Secondary follicles have multiple granulosa cell layers (stratified granulosa) but have not yet formed an antrum.
What hormones regulate primary follicle development?
Primary follicle growth is driven primarily by paracrine signals from the oocyte itself and the surrounding granulosa cells, with some FSH (follicle-stimulating hormone) sensitivity. Oocyte-derived growth factors (GDF-9, BMP-15) are particularly important for granulosa cell proliferation at this stage.

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Educational Disclaimer

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Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.