Histology - Ovarian Follicle

Primordial Follicle

The primary oocyte, which is arrested in meiosis I
A single layer of flat granulosa cells; the granulosa cells and oocyte interact to guide follicular maturation
A basement membrane (aka, lamina) surrounds the follicle
In puberty, follicles are cyclically "recruited" for further development

Primary follicle

The growing primary oocyte
Newly formed zona pellucida, which is thick a-cellular coat that covers the oocyte; It displays sperm receptors and facilitates the acrosome reaction necessary for fertilization; after fertilization, the zona pellucida prevents additional sperm from joining with the oocyte.
Single layer of granulosa cells transition from flat to cuboidal, which reflects their greater cellular activity.

Secondary follicle

Primary oocyte; has achieved meiotic and developmental competence (it is capable of completing meiosis and preparing for implantation).
Zona pellucida, and,
Multiple layers of cuboid granulosa cell (typically 6-9 layers)
Theca cells, which arise from the ovarian interstitium, begin to accumulate around the basement membrane of the secondary follicle.

Tertiary follicle

Secondary oocyte, which is the product of meiosis I (we've omitted the polar body)
Zona pellucida
Granulosa cells separated by the antrum
Cumulos oophorus is the collection of granulosa cells that support the secondary oocyte
Corona radiata is a subset of the cumulus oophorus that directly surround the zona pellucida.
Theca cells have diversified, and now form the theca interna and externa layers.
Of the late tertiary follicles, only one, the so-called "dominant follicle," is ovulated.

Ruptured follicle

Transitions physiologically and morphologically to become the corpus luteum, which acts as a temporary endocrine gland.
Ovulated secondary oocyte takes the corona radiata with it; in most cases, it is swept into the uterine tube and transported to the uterus for menstruation or implantation.