Histotopographic and ultrastructural study on the lymphatic network of the pancreas in the guinea pig

The localization of absorbing lymph vessels was studied in the normal guinea pig pancreas by light microscopy (serial semithin sections) and transmission electron microscopy (ultrathin sections). Absorbing lymph vessels were observed both in the interlobular and intralobular areas where they can be localized close to the adenomeres. Lymph vessels were also seen in the interlobular areas located next to the islets of Langerhans and to groups of endocrine cells (n = 8-10) not showing a vascular organization comparable with islets of Langerhans. All lymph vessels in the pancreas are absorbing lymph vessels, characterized by a very thin endothelial wall, anchoring filaments and the absence of a definitive basal membrane. Adjacent endothelial cells form end-to-end, overlapping and interdigitating intercellular junctions. Valves were present both in the interlobular and intralobular lymph vessels

Arrangement of the small intestine lymphatic network in the Peyer's patches of the mouse. A light and transmission electron microscopic study

4noreservedThe lymphatic network in Peyer's patches has been previously studied by scanning electron microscopy in rabbit and sheep. So far, data on the Peyer's patch lymphatic network obtained by light and transmission electron microscopy are still lacking. The present work was carried out on several series of consecutive thick and semithin sections of mouse Peyer's patches. Ultrastructural analyses were performed on ultrathin sections by traditional transmission electron microscopy. Lymph vessels were detected in the parafollicular and subfollicular areas of Peyer's patches. Two independent lymphatic plexuses, the muscularis mucosae lymphatic plexus and the subfollicular plexus, were identified respectively in the mucosal and submucosal layers. These lymphatic plexuses joined outside the patch, both draining into the submucosal lymphatic network of the small intestine. At the ultrastructural level, the muscularis mucosae lymphatic plexus, and the lymph vessels draining into it, showed a close association with bundles of smooth muscle cells. Numerous nerve fibres were detected in proximity to the lymphatic endothelium and, in some cases, synapse-like neuroendothelial associations were observed. We report here the lymph vessel organization observed in mouse Peyer's patches and discuss the meaning of the presence of subendothelial nerve terminalsmixedRegoli, Marì; Borghesi, Chiara; Bertelli, Eugenio; Comparini, LeonettoRegoli, Mari'; Borghesi, Chiara; Bertelli, Eugenio; Comparini, Leonett