Location of inclusion cysts in mouse ovaries in relation to age, pregnancy, and total ovulation number: implications for ovarian cancer?

• Published in: The Journal of pathology Vol. 205; no. 4; pp. 483 - 490
• Main Authors: Tan, Olivia L., Hurst, Peter. R., Fleming, Jean. S.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.03.2005; Wiley
• Subjects: Aging - pathology; Aging - physiology; Animals; Biological and medical sciences; Cell Transformation, Neoplastic; Epithelial Cells - chemistry; Epithelial Cells - pathology; Female; Immunohistochemistry - methods; Inclusion Bodies - pathology; Inclusion Bodies - physiology; inclusion cyst; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Mice; mouse; Ovarian Cysts - pathology; Ovarian Cysts - physiopathology; Ovarian Neoplasms - pathology; Ovarian Neoplasms - physiopathology; ovarian surface epithelium; ovary; Ovary - pathology; Ovary - physiopathology; ovulation; Ovulation - physiology; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Precancerous Conditions - pathology; Precancerous Conditions - physiopathology; Pregnancy; Proliferating Cell Nuclear Antigen - analysis; rete ovarii; Inclusion; Ovary cancer; Rodentia; Malignant tumor; inclusion cyst; Ovulation; ovarian surface epithelium; Female genital diseases; Pregnancy; Ovarian diseases; Vertebrata; Anatomic pathology; ovary; Mammalia; Number; Mouse; Animal; Female genital system; Cyst; Female; Benign neoplasm; rete ovarii; Age
• ISSN: 0022-3417; 1096-9896
• DOI: 10.1002/path.1719

Benign ovarian cysts are thought to be precursor lesions that differentiate and transform into carcinoma. With the aim of testing the hypothesis that increased ovulation number increases the frequency or number of ovarian cysts, the development and appearance of ovarian cysts was investigated in mice of differing ages and total lifetime ovulation number. High total ovulation number was induced by keeping mice in cages divided by a screen, with a male on one side and two females on the other side. Significantly more cysts were observed in animals subjected to incessant ovulation for 8 months and in 12 month breeding mice than in 3‐month virgin mice or 1‐month prepubertal animals. These cysts had the appearance of benign serous inclusion cysts. When cystic ovaries were serial sectioned, 47% of cysts had a connection to the ovarian hilus and potentially to the tubules of the rete ovarii, 31% were adjacent to the hilus, and 22% had an intra‐ovarian location. A significant increase in intra‐ovarian cysts was observed in the 8‐month incessant ovulation group, implying that high ovulation number leads to ovarian surface invagination and inclusion cyst formation. In conclusion, ovarian inclusion cysts may be derived from more than one epithelial source, but incessant ovulation may increase the proportion derived from the ovarian surface epithelium. Because the cysts observed resembled human serous inclusion cysts these results have possible implications for epithelial ovarian carcinoma. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.