Structural and Functional Components of the Feline Enteric Nervous System

Expression profile of some neuronal and glial cell markers in the ovine ileal enteric nervous system during prenatal development

The enteric nervous system (ENS) is a network of neurons and glia found in the gut wall and governs this gastrointestinal function independently from the central nervous system (CNS). ENS comprises the myenteric plexus (MP) and the submucous plexus (SP). In this study, we examined the expression profile of neurofilament heavy chain (NF-H), neuron-specific enolase (NSE), calcyclin (S100A6), vimentin and glial fibril acidic protein (GFAP) in ovine ileal enteric neurons and enteric glia cells (EGCs) during prenatal development using an immunohistochemical method. The material of the study consisted of 15 different fetal ileum tissues obtained between days 60 and 150 of pregnancy. NF-H was observed in the majority of ganglion cells in SP and MP throughout the fetal period. It was determined that there was no NF-H reaction in some ganglion cells in Peyer's patches of internal submucosal plexus (ISPF). In the early stage of pregnancy (60-90 days), there was no expression of NSE and S1006 in ileum. After this period, NSE and S1006 were expressed in the ganglion cells of the plexus, indicating an increase in the amount of expression towards the end of pregnancy. In the early period, vimentin expression was only detected in intramuscular interstitial cells (ICs) (60-90 days), but later (90-150 days) it was also seen in the cells around the ganglion cells in the plexus. On days 60-90 of gestation, GFAP expression only occurred in MP, but in later stages, staining was also detected in SP. In the plexus, an immunoreactivity was present in EGCs forming a network around the ganglion cell. During the last period of gestation (120-150 days), the number of GFAP-positive plexus increased, with the majority of these stained cells being observed in MP. Interestingly, weak staining or reaction did not occur in ISPF, unlike other plexuses. In conclusion, this is the first study that demonstrated the expression of NF-H, vimentin, S100A6, NSE and glial fibril acidic protein (GFAP) in ovine ileal ENS in the prenatal period. In the last period of gestation (120-150 days), the expression profile of ENS was similar to that of adult animals. The expression of the used markers increased toward the end of pregnancy. Our results suggest that neurons and EGCs show heterogeneity, and GFAP and NF-H cannot be used as panenteric glial or panneuronal markers, respectively. We also demonstrated, for the first time, the prenatal expression of S100A6 in enteric neurons and the possibility of using this protein for the identification of enteric neurons.

Immunohistochemical evaluation of the goat forestomach during prenatal development

Here we report the detection and distribution of synaptophysin (SPY), non-neuronal enolase (NNE), glial fibrillary acidic protein (GFAP), vimentin (VIM), neuropeptide Y (NPY), and vasoactive intestinal peptide (VIP) expression in the goat forestomach during prenatal development. A total of 140 embryos and fetuses were examined to evaluate protein expression from the first stage of prenatal life until birth. In all cases, SPY immunoreactivity was detected at 53 days gestation in the lamina propria-submucosa, tunica muscularis, serosa, and myenteric plexuses. Immunoreactivity to NNE was observed at 64 days gestation in the same locations as well as the epithelial layer. Glial cells were found at 64 days as indicated by signals corresponding to GFAP and VIM at 39 days. Positive staining for NPY and VIP was observed at 113, 75, and 95 days in the rumen, reticulum, and omasum, respectively, in the lamina propria-submucosa, tunica muscularis, and myenteric plexuses of each of these gastric compartments. These findings indicate possible preparation of the fetal goat forestomach for postnatal function. Compared to other ruminant species, neuroendocrine cells, glial cells and peptidergic innervations markers were detected earlier compared to sheep but at around the same stage as in deer.