Regional differences in the ultrastructure of mucosal macrophages in the rat large intestine.

We previously clarified the histological characteristics of macrophages in the rat small intestine using serial block-face scanning electron microscopy (SBF-SEM). However, the regional differences in the characteristics of macrophages throughout the large intestine remain unknown. Here, we performed a pilot study to explore the regional differences in the ultrastructure of mucosal macrophages in the large intestine by using SBF-SEM analysis. SBF-SEM analysis conducted on the luminal side of the cecum and descending colon revealed macrophages as amorphous cells possessing abundant lysosomes and vacuoles. Macrophages in the cecum exhibited a higher abundance of lysosomes and a lower abundance of vacuoles than those in the descending colon. Macrophages with many intraepithelial cellular processes were observed beneath the intestinal superficial epithelium in the descending colon. Moreover, macrophages in contact with nerve fibers were more prevalent in the cecum than in the descending colon, and a subset of them surrounded a nerve bundle only in the cecum. In conclusion, the present pilot study suggested that the quantity of some organelles (lysosomes and vacuoles) in macrophages differed between the cecum and the descending colon and that there were some region-specific subsets of macrophages like nerve-associated macrophages in the cecum.

Alteraciones en la citomembrana y celulas de superficie del intestino grueso por accion de los edulcorantes / Changes of cytomembrane and surface cells of the large intestine by sweetening agents action

Se ha demostrado que la sacarina y los ciclamatos provocan lesiones en el organismo. Describimos en este trabajo las alteraciones producidas por estas drogas en ratones alimentados con una solución de sacarina y ciclamato al 1/1000, durante 90 días. El estudio ultraestructural revela: Hipertrofia microvellositaria e incremento membranoso mitocondrial en las células absortivas y alteraciones en la secreción de células calciformes. Estas modificaciones son fenómenos de respuesta celular por interferencia o acción mutágena sobre el ADN nuclear o metabolismo citoplasmático. Los autores agradecen a la señora Carolina S. de Santolaya por el apoyo técnico realizado. Esta investigación fue apoyada financieramente por el Consejo de Investigación de la Unviersidad Nacional de Tucumán