Goblet cell hyperplasia and muscular layer thickening in the small intestine of a cynomolgus monkey

Abstract

We report here the interesting case of a 5-year-old male cynomolgus monkey with goblet cell hyperplasia and thickening of the muscular layer throughout the small intestine without exhibiting any clinical symptoms. Necropsy examination showed diffuse thickening of the intestinal wall from the jejunum to the ileum, with an appearance likened to a rubber tube. Histopathologically, marked thickening was observed in both the mucosal and muscular layers in the jejunum and ileum, and slight thickening was observed in the duodenum. Goblet cell hyperplasia with extension of the circular folds and villi was prominently observed. The mucosal surface was covered with a thick mucus layer containing desquamated mucosal epithelial cells, and both the inner and outer muscular layers were markedly thickened due to smooth muscle hypertrophy. Neither macroscopic nor histopathological examination identified any causative factors, such as infection, enteritis and intestinal stenosis, or obstruction that may have caused development of this lesion. Given these observations, this case may simply be considered of spontaneous goblet cell hyperplasia and muscular layer thickening in the small intestine of a cynomolgus monkey.

Keywords: cynomolgus monkey; goblet cell hyperplasia; intestinal smooth muscle; muscular layer thickening.

Fig. 1

Gross appearance of the mucosal surface of the ileum from the present case (A) and a normal monkey (B). A: Thickening of the mucosal folds and conglomerated mucus (arrows) on the mucosal surface. B) Normal appearance.

Fig. 2

Photomicrographs of the ileum from the present case (A, C, E, G) and a normal monkey (B, D, F, H). A: Marked thickening of both the mucosal and muscular layers. C: Hyperplasia of the goblet cells with extension of the villi. E: PAS-positive reaction in the mucus of hyperplastic goblet cells. G: Marked thickening of both the inner and outer muscular layers due to smooth muscle hypertrophy. B, D, F, H: Normal appearance. A, B: H&E, bar=1000 μm. C, D: Higher magnification of A and B, H&E, bar=200 μm. E, F: PAS, bar=100 μm. G, H: H&E, bar=100 μm.