Nonproliferative and Proliferative Lesions of the Rat and Mouse Female Reproductive System

Abstract

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the female reproductive tract of laboratory rats and mice, with color photomicrographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. There is also a section on normal cyclical changes observed in the ovary, uterus, cervix and vagina to compare normal physiological changes with pathological lesions. A widely accepted and utilized international harmonization of nomenclature for female reproductive tract lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Spontaneously Arising Tumours and Tumour-like Lesions of the Cervix and Uterus in 83 Pet Guinea Pigs ( Cavia porcellus )

“…It is noteworthy to mention that 10/23 endometrial neoplasms (adenomas and one adenocarcinoma) revealed focal decidualizations. Similar changes have been described in rats and mice, where these focal decidualizations occur in conjunction with polyps or other tumours or induced hormonal changes (Dixon et al, 2014).…”

“…Both are similar changes. In accordance with descriptions in the rat and mouse (Dixon et al, 2014), we referred to 'focal decidualization' when the lesions were part of another change (i.e. adenoma or adenocarcinoma) (Fig.…”

Background data on NOD/Shi-<i>scid</i> IL-2Rγ^null mice (NOG mice)

“…Judging from the histological nature and the mode of incidences, the other histologic changes than the above-mentioned ones were considered not to be specific for NOG mice (Kaufmann et al, 2012;Pearse, 2006b;Khosla and Ovalle, 1986;Hardisty andBoorma., 1999: Leininger et al, 1999;Creasy et al, 2012;Dixon et al, 2014;Long and Leininger, 1999).…”

Chlamydia muridarum Induction of Glandular Duct Dilation in Mice

“…Progesterone has been shown to inhibit uterine gland development in the neonatal mouse uterus (31,32), while estrogen seems to be required for maintaining uterine gland function in adult mice (33). Aged mice can spontaneously develop cystic endometrial hyperplasia (34), which involves dilation and proliferation of the glandular ducts. The glandular duct cysts vary in size but are restricted within the endometrium.…”

“…Adenomyosis refers to the invasion of hyperplastic glands into the myometrium (35), which can be difficult to differentiate from endometriosis (36) when the dislocated endometrial tissue is still associated with the uterus. Hydrometra may also cause uterine horn dilation (34), which is, however, due to uterine horn lumenal distension without involving the uterine glands. Finally, uterine tumors with or without gland involvment can cause uterine horn dilation.…”