J. Kaspareit

Spontaneous squamous cysts and squamous epithelial plaques in the heart of cynomolgus monkeys (Macaca fascicularis)

Squamous cysts and squamous epithelial plaques were observed in a total of seventeen cynomolgus monkeys. Eleven monkeys had squamous cysts, three of them also revealed squamous plaques and six revealed squamous plaques exclusively. At necropsy, cysts were recognized as yellow-white nodules with a smooth surface, that were located superficially along the interventricular septum, on the surface of the left ventricle or the apex of the heart. Microscopically, cysts were lined by a flattened epithelium and filled with keratin. Occasionally the epithelium was multi-layered or replaced by a rim of foreign body-type multinucleated giant cells. All animals with squamous cysts came from Mauritius, while those with squamous plaques came from Mauritius, China and Vietnam. As discussed in man, squamous cysts and plaques in cynomolgus monkeys are considered to represent displaced foregut epithelium, that was sequestered in the dorsal mesocardium prior to closure of the pleuropericardial fold during early embryologic development.

Spontaneous pulmonary neoplasms in cynomolgus monkeys (Macaca fascicularis) — A report of two cases —

The first lung tumour-bearing animal was a 7 years and 3 months old cynomolgus monkey. Microscopic examination revealed a neoplastic mass under the pleura that consisted of squamous islands with little keratinization, multifocal mineralization of the keratin, inflammatory cell and foreign body-type giant cell infiltration. It was classified as pulmonary squamous cell carcinoma. In a second cynomolgus monkey (2 years and 10 months old) a lung mass was observed at necropsy. Microscopically the tumour consisted of numerous islands of cartilage with glandular structures lined by a cuboidal epithelium between them. The neoplasm was classified as cartilaginous hamartoma.

Considering the Use of Callithrix jacchus

Abstract In this chapter we review the data available on the use of marmosets as a valuable NHP model and report on histopathological specificities in a variety of organs. Based on the differences described, the marmoset model is discussed in the context of toxicological safety assessments as well as a model for general research on the pathophysiology of human diseases.

Spontaneous extracutaneous systemic mastocytosis in a cynomolgus macaque (Macaca fascicularis)

A uniform cell population of proliferating mast cells with poor cytoplasmic granularity and a few eosinophilic infiltrates was observed in hepatic portal tracts and the cecal submucosa of an adult male cynomolgus macaque (Macaca fascicularis) that was part of a drug safety assessment toxicity study. The proliferating mast cells were positive for Giemsa and toluidine blue staining and had strong immunoreactivity for mast cell tryptase and CD68. Considering size, morphology, immunoreactivity, and distribution of the lesions a benign proliferative disorder of connective tissue mast cells was diagnosed comparable to that seen in indolent systemic mastocytosis in humans, but lacking associated skin lesions. The finding of visceral mast cell proliferation has to be included in the spontaneous background pathology spectrum of cynomolgus macaques used in toxicological studies.

Testicular and epididymal appendages in the cynomolgus macaque (Macaca fascicularis)

Background  Vestigial remnants of the mesonephric duct and paramesonephric duct are well‐known developmental abnormalities of the human testis and epididymis.