Figure 1.

Morphological characteristics of rat ovaries: a) metestrous; b) diestrous; c) proestrous; and, d) estrus. The ovaries presented different morphological patterns; in the ovaries in metestrous the corpora lutea was more evident than in the other phases of the cycle (arrowheads), Atretic follicles with different degrees of degeneration were observed (arrows) in all phases of the cycle. Under high magnifications (a1, a2, b1, b2, c1, c2, d1, and d2), all follicles are in different stages of the process of atresia and show altered oocytes with irregular shapes and cytoplasmic regions with clear vesicles (crossed arrows). The oocyte in c1 is segmented in two nucleated pseudo-blastomers with large nucleoli. o, oocyte; gc, granulosa cells. Scale bars: a, b, c, and d, 200 microns; all others 50 µm.