ABSTRACT
Many people who work in laboratory rodent breeding facilities believe that disrupting certain sensitive rodent lines will result in increased breeding failures and loss of newborn pups. To evaluate this hypothesis, the authors assessed the effect of cage-change frequency on the breeding performances of a mouse strain (C57BL/6NTac) and a rat stock (NTac:NIH-Whn) that were thought to be sensitive to disruption. As per recommendations in the Guide for the Care and Use of Laboratory Animals, personnel changed one half of the breeding cages weekly, regardless of the presence of newborn pups. The other breeding cages were also changed weekly, unless newborn pups were present, in which case the cages were not changed until the following week. The authors assessed breeding performance by calculating the production efficiency index (the total number of pups that survived to weaning divided by the total number of actively breeding females). Breeding performance did not differ significantly between rodents whose cages were changed weekly and those whose pups were not disturbed.
Subject(s)
Animal Husbandry/methods , Behavior, Animal , Housing, Animal , Reproduction/physiology , Animals , Animals, Newborn , Exploratory Behavior/physiology , Female , Litter Size , Longevity/physiology , Male , Mice , Mice, Inbred C57BL , Rats , Rats, Inbred Strains , WeaningABSTRACT
A case of epidermotropic lymphoma with systemic spread into lymph nodes and visceral organs was observed in a 7- to 8-month-old, female ICR mouse. The mouse developed progressive and generalized alopecia and lymphadenopathy of several weeks' duration. The affected skin was markedly and diffusely thickened, with multiple serous to hemorrhagic crusts, ulcerated plaques, and raised nodules. Microscopically, random and/or perivascular infiltration of pleomorphic lymphoid cells was present in the skin, lymph nodes, thymus, spleen, lungs, and liver. On cytologic examination, the lymphoid cells were similar in all affected tissues, and had hyperchromatic and irregularly oval, cleaved, and occasionally convoluted nuclei, approximately 6 to 9 mm in diameter. On immunohistochemical examination, most infiltrating cells were labeled with anti-CD3 (panT cell) antibody. A smaller proportion of the cells (, 5%) were labeled with anti-CD79a (panB cell) antibody.
ABSTRACT
Diseases of bulbourethral glands have rarely been reported in mice. The present report describes bulbourethral gland cysts in three male mice: a.1yearold DBA/2J mouse (case 1), a 10monthold nude mouse (case 2), and a 4.5monthold chimeric mouse (case 3). Round to oval fluctuant nodules were observed on their dorsal perineum. The nodules in cases 1 and 2 were pale, pink to tan, soft, and glistening; in case 3, the mass was purple-red and soft. All nodules were located subcutaneously between the bulbospongiosus and ischiocavernous muscles, with a deep connection to the urethra. The nodules were 13 mm (case 1), 6 mm (case 2), and 8 mm (case 3) in diameter. The cut surface of the nodules was cystic; the lumina were filled with clear gelatinous or viscous (cases 1 and 2) or thin blood-tinged fluid (case 3). The nodules comprised irregular cysts and acini that were lined by a single layer of cuboidal, pyramidal to tall columnar epithelial cells with little stroma. Bulbourethral gland cysts should be included as differential diagnoses for perineal nodules or swellings in mice.
