Follicles mature, mainly under the influence of hormones released by the pituitary gland
Different stages of maturation are described:
Primordial
Primary
Secondary
Graafian
When a Graafian follicle matures, it ruptures to release its ovum
It then undergoes changes to form a corpus luteum; this is the endocrine gland which secretes the hormones of pregnancy and maintains the development of the embryo and placenta
Follicles may break down at any stage of their development (most do!)
They are then known as atretic follicles
Corpora lutea also breakdown and are then known as corpora albicans
The naming of follicles is not standardised across all texts
It may even vary from one edition of a text to another!