Prenatal histomorphological development of the reticulum in fallow deer (Dama dama)

The histomorphological changes occurring in the Dama dama reticulum during prenatal development have been investigated. Twenty-five Dama dama embryos were used, from the first stages of prenatal life until birth. Differentiation of the reticulum was observed at 23% gestation. By 25% gestation the reticular wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Primary reticular crests were visible at 38% gestation. Secondary reticular crests were observed at 61% gestation. Neuroendocrine cells were detected by synaptophysin (SYP) at 35% gestation, in the lamina propria-submucosa, tunica muscularis, and serosa. Epithelial Cytokeratin-18 (CK-18) cells were observed at 35% gestation extended throughout the epithelial layers. The glial cells (vimentin -VIM- and glial fibrillary acidic protein-GFAP-markers) were discerned at 25% and 43% gestation, respectively, in myenteric and submucosal plexuses, lamina propria, muscularis mucosae, tunica muscularis, and perivascular connective tissue. The neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) markers were immunodetected at 75% and 80 gestation, respectively, in the lamina propria-submucosa, muscularis mucosae, tunica muscularis, serosa, and myenteric plexuses. The prenatal development of the fallow deer reticular mucosa evidenced a considerable precocity similar to that previously reported in goat and red deer.

Reticular groove of the domestic ruminants: histochemical and immunocytochemical study

The reticular groove mucosa of adult cattle, buffalo and sheep was investigated by histochemical and immunocytochemical techniques. Intense NADPH-d staining was observed in the folds of the epithelium mucosa and at the bottom of the reticular groove in all domestic ruminants studied. The NADPH-d staining showed that the innervations of the tunica muscularis of the reticular groove lip were composed of nerve corpuscles, nerve fibres and nerve cells of the mucosa epithelium. SEM analysis showed an intense nitric oxide synthase (NOS) I immunoreactivity in deep and medium cellular layers. It is interesting to note that the same morphologies were observed in samples of the mucosa epithelium, and of the tunica muscularis processed by NADPH-d and in those processed by immunogold techniques. This study has demonstrated that nitric oxide (NO) is involved in the rumination activity and that it plays a double role in this activity in the reticular groove of all domestic ruminants studied: (1) NO plays a role similar to the one it has in the mucosa epithelium of all the other compartments of the ruminant forestomach, (2) The lip sections of the reticular groove has shown abundant innervations that may indirectly coordinate and control the forestomach motility through the direct activation of the nitrergic (nitroxidergic) nerve cells and nerve fibres.