Quantification of polyoocyte follicles (POFs) in domestic cats

Ovarian follicles usually involve only one oocyte. However, the existence of follicles with more than one oocyte has been described in different species. Therefore, this study evaluated the occurrence and number of Polyoocyte Follicles (POFs) in the ovaries of cats undergoing the ovariohysterectomy technique. For this purpose, ovaries from 33 cats were collected and submitted to histological preparation and analysis. The slides were evaluated under a microscope by two evaluators, who quantified the presence of follicles containing one or more oocytes and classified the follicular stage. Monoocyte follicles (MOFs) were found in all ovaries. POFs were observed at similar frequencies in both the right and left ovaries. The frequency of POFs with two oocytes was 79.03% in the right ovaries and 75.75% in the left ovaries. Follicles with three oocytes were found in 16.12% of the right ovaries and 27.27% of the left ovaries. The mean number of follicles with zero, one, two, three or more oocytes was similar between the ovaries, being 6.58, 310.5, 3.25, and 0.29 in the right ovary and 6.25, 312.7, 4.25, and 0.41 in the left ovary (p-values ​​of 0.7569, 0.9654, 0.4785, and 0.5015, respectively). POFs containing from two to five oocytes were identified in different stages of development. POFs at all stages of development were found in both ovaries, and the occurrence of these structures was influenced by the age, number of pregnancies, number of estrus, and weight of the cats studied.