Reproductive System, Female

Ovary, Follicle - Polyovular

Narrative

Comment:

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.

Recommendations:

Ovary, Follicle - Polyovular should be diagnosed when present, but severity grading is not necessary.

References:

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.

All Images

Ovary - Normal in a female B6C3F1/N mouse from a subchronic study. The two adjacent follicles are distinct; compare with Figure 2.

Ovary, Follicle - Polyovular in a female B6C3F1/N mouse from a subchronic study. One follicle contains two oocytes, in contrast to the adjacent follicles shown in Figure 1.

Authors and Reviewers

Authors

Gabrielle Willson, BVMS, Dip RC Path, FRC Path, MRCVS
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Karen Y. Cimon, DVM, MS
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Reviewers

Karen S. Regan, DVM, DABT, DACVP
Pathologist
Regan Path/Tox Services, Inc.
Ashland, OH  

Darlene Dixon, DVM, PhD, DACVP, Fellow, IATP
Group Leader, Molecular Pathogenesis Group
National Toxicology Program Laboratory
National Toxicology Program
National Institute of Environmental Health Sciences, Research Triangle Park, NC