Morphological and Immunohistochemical Identification of Villous M Cells in the Small Intestine of Newborn Piglets

Abstract

SUMMARY: Microfold (M) cells act as antigen-sampling sites for initiating antigen specific mucosal immune responses, but they may also provide a gateway for enteropathogen entry. In this study we demonstrated villous M cells by morphological and immunohistochemical methods to be present in the three regions of the small intestine from newborn piglets. Immunohistochemical analysis, using anti-cytokeratin 18 (CK18) primary antibodies, showed a gradually decreased density of M cells from the lower crypt epithelium to the upper villous epithelium. The proportion of villous M cells was greater in the ileum than in the duodenum or the midjejunum. Ultrastructural observation revealed that villous M cells were mainly columnar in shape in the duodenum and the mid-jejunum, and appeared as more pocket-like structure in the ileum. These villous M cells exhibited short and irregular microvilli, rich vesicles and reduced glycocalyx, but lacked the lymphocyte-containing basolateral invagination. Our results support evidence that M cells can develop in the small intestinal villous epithelium of newborn piglets, implying that villous M cells may begin developing in the pig's small intestine during fetal stages, which depends neither on the influence of the mucosal lymphoid tissue nor the antigen from the intestinal lumen stimulation. In addition, the variable morphology and heterogeneity distribution of villous M cells in the three regions of the small intestine may be indicative of its different functional properties. This information extent our understanding of the diversity of M cells and provides important basic knowledge for further research on the actual role of villous M cells in neonate.

Small intestinal mucosal cells in piglets fed with probiotic and zinc: a qualitative and quantitative microanatomical study

“…The transmission electron microscopy revealed less electron-dense cytoplasm containing abundant mitochondria, lysosomes and small vesicles with few secretory granules. The present findings had a close resemblance to the findings of Renfeng et al [43] in piglets. In the present study, the differences in M-cells between control and treatment group piglets could not be made due to constraints in enough exposure availability of transmission electron microscopy.…”

Expression of the Microfold Cells in Three-Dimensional Coculture System for in Vitro Cultivation of Human Norovirus

“…Moreover, the evaluation of in vivo M cells from mouse Peyer's patches also presented similar results with the appearance of unique morphological structure with lack, blunted and shorter microvilli [6,18,19]. The same characteristic of microvilli was also observed on the small intestine of the newborn piglets, whereby the villous M cells showed depressed, short stub-like microvilli as compared to enterocyte epithelium [20].…”

Histology, histochemistry and ultrastructure of the nasopharyngeal tonsil of the buffalo (Bubalus bubalis)

“…M‐cells are highly heterogeneous in proportion and phenotype among the different species (Brayden & Baird, ) and various histochemical markers for their detection have been established (Casteleyn et al, ; Renfeng et al, ). Earlier, Kumar et al () identified M‐cells in the FAE of the equine nasopharyngeal tonsil on the basis of short microvilli, an intimate association with lymphocytes, cytoplasmic vimentin filaments and epitopes on the apical surface reactive with lectin GS‐1‐B4 specific for α‐linked galactose.…”