Individual follicles may be closely adjacent to each other (Figure 1). Each of these follicles contains one oocyte. A polyovular follicle comprises a single follicle containing two oocytes, each with its own nucleus, zona pellucida, and layer of granulosa cells (Figure 2). Polyovular follicles are occasionally seen as a background finding but have been recorded as a treatment-related finding in mice in one subchronic NTP study.
Ovary, Follicle - Polyovular should be diagnosed when present, but severity grading is not necessary.
Maekawa A, Maita K, Harleman JH. 1996. Changes in the ovary. In: Pathobiology of the Aging Mouse (Mohr U, Dungworth DL, Capen CC, Carlton WW, Sundberg JP, Ward JM, eds). ILSI Press, Washington, DC, 451-467.