Ovary from cat (40X)

At this magnification it is possible to see the different stages of the follicular maturation. Most peripherally lie the primordial follicles, which are the first stage. Further centrally from these, lie the primary follicles, which are the next stage of the follicular maturation. The secondary follicles lie closer to the medulla. These are much bigger than the first to stages of follicular maturation. They are easily recognized because they contain a space filled with fluid, called the follicular antrum (lat: antrum folliculi). The Graafian follicle is the follicular stage after the first meiotic division but before ovulation. It therefore contains a 2N haploid oocyte. It is characterized by a large follicular antrum that makes up most of the follicle. There are some atretic follicles in this view (follicles that are degenerating).