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

Abstract

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic 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 and differential diagnosis for classifying microscopic lesions observed in the male reproductive system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the Internet (http://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. A widely accepted and utilized international harmonization of nomenclature for lesions of the male reproductive system 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.

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).…”

Interpreting histopathology in the epididymis

“…[51][52][53][54][55] Debris/germ cells in the epididymal lumen The lumen of a normal adult rat epididymis contains very few sloughed germ cells or cellular debris. The most common source of cells and cellular debris in the lumen of the epididymis occurs from sloughed germ cells secondary to spermatogenic disturbances or androgen deprivation (causing sloughing of round spermatids) in the testis (Fig.…”

Uncertainties of testing methods: What do we (want to) know about carcinogenicity?

“…Such as peroxisome proliferation leading to liver tumours, forestomach and thyroid cancers (Boobis et al, 2006;Proctor et al, 2007;Meek et al, 2014). Age associated tumors are common and variable amongst rodent species and strains, e.g., Leydig cell tumors (Creasy et al, 2012;WHO, 2015).…”