Morphometric and cytochemical analysis of lysosomes in rat Peyer's patch follicle epithelium: Their reduction in volume fraction and acid phosphatase content in M cells compared to adjacent enterocytes

Abstract

M cells are specialized epithelial cells over lymphoid follicles in Peyer's patches which take up viruses, bacteria, and antigenic macromolecules from the intestinal lumen. Unlike ordinary enterocytes which sequester pinocytosed material in lysosomes, M cells transport such material across the epithelium to antigen-processing areas in lymphoid follicle domes, suggesting a difference in lysosomal activity or a different route for movement of endocytic vesicles. Ileal Peyer's patches in rats were examined by electron microscopy to identify lysosomes by acid phosphatase activity. Acid phosphatase was found in dense bodies in enterocytes but not in M cells. Stereological analysis showed the volume fraction occupied by dense bodies in M cells to be 16 times less than in enterocytes (P less than .0005), even though the volume fractions of cytoplasm occupied by mitochondria in M cells and enterocytes were not significantly different. The small volume fraction of dense bodies and the absence of acid phosphatase activity in M cells thus correlate with absence of lysosomal degradation of luminal microorganisms during transport into lymphoid follicles by M cells and may provide not only a complete array of microbial antigens for initiation of immune responses, but also a route through the mucosal barrier for microorganisms which can evade local containment mechanisms.

Phagocytosis and transcytosis by the follicle‐associated epithelium of the ileal Peyer's patch in calves

“…The present results suggest that the route through the epithelial cells involves lysosomal degradation. Transcytosis of macromolecules is also a well known ability for M cells (12), but their handling of internalized material may not involve lysosomal inclusion (13).…”

Bacterial Translocation from Intestine: Microbiological, Immunological and Pathophysiological Aspects

“…Необходимо отметить общебиологическое значение БТ, которое не является простым пассивным процессом, а предусматри-вает активный микробный забор (Sampling) с участием фагоцитирующих клеток и опсонических гуморальных факторов (комплемент, антитела и др.). В механизмах мукозного иммунитета и взаимодействия с кишечными бактериями и лимфоидной тканью, ассоциированной со слизистой оболочкой кишечника, в частности с Пейеро-выми фолликулами, особую роль играют так называемые М клетки [27,28]. Их способность к эндоцитозу кишеч-ных бактерий повышается при участии гликопротеина 2, играющего определенную опсонизирующую роль и сти-мулирующего мукозный иммунный ответ [29,30].…”

Immunology

“…B, C ! 7,000. morphometric analysis of lysosomes in M cells, Owen et al [97] established that the small volume fraction of dense bodies (lysosomes) in M cells provides an explanation for transport of luminal material across the epithelium by M cells without lysosomal degradation. Both soluble molecules, such as horseradish peroxidase [96,100] and viable micro-organisms such as Salmonella typhimurium [44], have been shown to be taken up by M cells after entering PP in mice.…”