Expression of alpha-smooth muscle actin as special and morphometric assessment in the small intestine during the postnatal development in hamster

Abstract

Immunoreactivity of alpha-smooth muscle actin (ASMA), along, with morphometric values in the hamster small intestine, was examined during postnatal development. Twelve healthy hamsters were divided into three age groups of 2·5 months (group 1), 3 months (group 2), and 4 months (group 3). For morphometrical study, routine tissue processing was carried out by autotechnicon tissue processor, the processed tissues were embedded and sectioned serially into 5-μm thick sections. The sections were stained with hematoxylin and eosin (H&E). Immunohistochemistry (IHC) was performed by primary antibodies against alpha-smooth muscle actin (ASMA). All samples showed ASMA expression in the muscularis mucosa and circular and longitudinal layers of muscularis propria. The small intestine samples in group 1 showed minimal ASMA expression in total muscular layers. Alpha-smooth muscle actin labeling was increased in groups 2 and 3 in the muscularis mucosa and both layers of inner and outer circular muscle as compared to group 1. A more intense ASMA expression was observed in the longitudinal layers in both groups 2 and 3. The morphometrical results showed that there was a smaller increase in thickness of the mucosa, submucosa, and muscular layers from group 1 to group 2 that was followed by a larger increase between groups 2 and 3. There were significant increases in thickness of all morphometrical parameters (mucosa, submucosa, and muscularis) in groups 2 and 3 in comparison with group 1, and also group 3 compared with group 2. In groups 2 and 3, thickness of the submucosa and muscular layers were significantly higher in the jejunum compared with the ileum.