Immunohistochemical study of the distributions of the peptide- and catecholamine-containing nerves in the omasum of the sheep

Age-associated changes of the intrinsic nervous system in relation with interstitial cells in the pre-weaning goat rumen

In this study, we investigated the neural changes and their relationships with interstitial cells (ICs) in the rumen of pre-weaning goats by transmission electron microscopy, western blot and immunofluorescence (antibody: general neuronal marker-Protein Gene Product (PGP9.5)/ IC marker-vimentin). The immunofluorescence results showed that PGP9.5-positive reaction was widely distributed in neuronal soma (NS) and nerve fibre (NF). The NSs were observed in the ganglia of the myenteric plexus (MP) but not in the submucosal plexus. The mean optical density (MOD) of the whole of PGP9.5-positive nerves and the protein expression level of PGP.5 in the rumen wall both decreased significantly with age. However an obvious increase MOD of PGP.5-positive NFs within the rumen epithelium were observed. In the MP, the nerves and ICs were interwoven to form two complex networks that gradually tightened with age. Furthermore, NSs and nerve trunks were surrounded by a ring-boundary layer consisting of several ICs that became physically closer with aging. Moreover, ICs were located nearby NFs within the ML, forming connections between ICs, smooth muscle cells and axons. This study describes the pattern of neural distribution and its association with ICs in the developing rumen which shed light on the postpartum development of ruminants.

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.

Role of tachykinins and neurokinin receptor subtypes in the regulation of motility of the forestomach and abomasum in conscious sheep

The present study was planned to evaluate role of tachykinins (TKs) and neurokinin (NK) receptors in the regulation of gastric motility in sheep. We examined the effects of intravenous (i.v.) injection of neurokinin A (NKA) and substance P (SP) on motility of the rumen, omasum, and abomasum in conscious sheep and the effects of NK receptor blockade on the effect of TKs using NK-1 receptor antagonist L-732,138 and NK-2 receptor antagonist SR48968. Moreover, the effect of NK receptor blockade on omasal cyclic contractions was examined. Intravenous injection of NKA and SP induced tonic contraction of rumen, omasum, and abomasum, and the contractile effect of NKA was more potent than that of SP in all the gastric regions. Although the effect of SP was not inhibited by L-732,138, the effect of NKA was significantly inhibited by SR48968. However, single infusion of SR48968 and L-732,138 did not alter cyclic electromyographic activity and basal intraluminal pressure in the omasum. These results imply that NKA and NK-2 receptors play a primary role in non-cholinergic regulation of ovine gastric motility, though NK-2 and NK-1 receptors seem unlikely to be involved in the physiological regulation of omasal cyclic contractions.

Evaluation of differences between breeds for substance P, vasoactive intestinal polypeptide, and neurofilament 200 in the abomasal wall of cattle

OBJECTIVE

To compare the content of substance P, vasoactive intestinal polypeptide, and neurofilament 200 in biopsy specimens taken from the abomasal wall of healthy cows of 2 breeds.

SAMPLE POPULATION

Biopsy specimens taken from different sites of the abomasal wall from 20 German Holstein cows and 20 German Fleckvieh cows.

PROCEDURES

Biopsy specimens were examined immunohistochemically, and the content of substance P, vasoactive intestinal polypeptide, and neurofilament 200 was determined by measuring the immunoreactive areas.

RESULTS

Significant differences between the breeds were detected. Substance P-immuno-reactive area in the corpus abomasi was significantly smaller in the German Holsteins (geometric mean +/- geometric SD, 679 +/- 1.83 microm2) than in the German Fleckvieh cows (1,020 +/- 1.65 microm2). Concerning vasoactive intestinal polypeptide, differences between breeds were not significant. Overall nerve density in the antral abomasal wall was significantly greater in German Holsteins than in German Fleckvieh cows (immunoreactive areas for neurofilament 200 in German Holsteins was 4,842 +/- 1.29 microm2 and in German Fleckvieh cows was 3,333 +/- 1.63 microm2). Conclusions and Clinical Relevance-The significantly lower content of substance P in the corpus abomasi could explain why German Holstein cows are predisposed to abomasal displacement, compared with German Fleckvieh cows, in which this disease is a rare finding.

Morphometric and immunohistochemical study of the abomasum of red deer during prenatal development

The red deer is well suited to scientific study, given its economic importance as an animal to be hunted, and because it has a rich genetic heritage. However, there has been little research into the prenatal development of the stomach of ruminants in general, and none for the red deer. For this reason, we undertook histological evaluation of the ontogenesis of the abomasum in red deer. Histomorphometric and immunohistochemical analyses were carried out on 50 embryos and fetuses from the initial stages of prenatal life until birth. The animals were divided for test purposes into five experimental groups: group I [1.4-3.6 cm crown-rump length (CRL); 30-60 days, 1-25% of gestation]; group II (4.5-7.2 cm CRL; 67-90 days, 25-35% of gestation); group III (8-19 cm CRL; 97-135 days, 35-50% of gestation); group IV (21-33 cm CRL; 142-191 days, 50-70% of gestation) group V (36-40 cm CRL; 205-235 days, 75-100% of gestation). In the organogenesis of the primitive gastric tube of red deer, differentiation of the abomasum took place at 67 days, forming a three-layered structure: the epithelial layer (pseudostratified), pluripotential blastemic tissue and serosa. The abomasal wall displayed the primitive folds of the abomasum and by 97 days abomasal peak areas were observed on the fold surface. At 135 days the abomasal surface showed a single mucous cylindrical epithelium, and gastric pits were observed in the spaces between abomasal areas. At the bottom of these pits the first outlines of glands could be observed. The histodifferentiation of the lamina propria-submucosa, tunica muscularis and serosa showed patterns similar to those described for the forestomach of red deer. The abomasum of red deer during prenatal life, especially from 67 days of gestation, was shown to be an active structure with full secretory capacity. Its histological development, its secretory capacity (as revealed by the presence of neutral mucopolysaccharides) and its neuroendocrine nature (as revealed by the presence of positive non-neuronal enolase cells and the neuropeptides vasoactive intestinal peptide and neuropeptide Y) were in line with the development of the rumen, reticulum and omasum. Gastrin-immunoreactive cells first appeared in the abomasum at 142 days, and the number of positive cells increased during development. As for the number of gastrin cells, plasma gastrin concentrations increased throughout prenatal life. However, its prenatal development was later than that of the abomasum in sheep, goat and cow.

Morphometric and immunohistochemical study of the omasum of red deer during prenatal development

The red deer is an important study species because of its value in the national economy and because it provides a wealth of genetic material. To date, there has been little research into the prenatal development of the stomach of ruminants, and none of the red deer. We therefore performed a histological evaluation of the ontogenesis of the omasum in the red deer. Histomorphometric and immunohistochemical analyses were carried out on 50 embryos and fetuses of deer from the initial stages of prenatal life until birth. For test purposes, the animals were divided into five experimental groups: Group I (1.4-3.6 cm crown-rump length, CRL; 30-60 days, 1-25% of gestation); Group II (4.5-7.2 cm CRL; 67-90 days, 25-35% of gestation); Group III (8-19 cm CRL; 97-135 days, 35-50% of gestation); Group IV (21-33 cm CRL; 142-191 days, 50-70% of gestation); and Group V (36-40 cm CRL; 205-235 days, 75-100% of gestation). At 67 embryonic days, the omasum wall was differentiated, and comprised three layers: the epithelial layer, pluripotential blastemic tissue and serosa. The stratification of the epithelial layer was accompanied by changes in its structure, with the appearance of four laminae of different sizes; in order of appearance these were: primary at 67 days, secondary at 90 days, tertiary at 97 days and quaternary at 135 days. At around mid-gestation, lateral evaginations were formed from the stratum basale of the primary and secondary smaller laminae. These were the primitive corneum papillae. From 205 days, the corneum papillae were present in all four sizes of laminae. The histodifferentiation of the lamina propia-submucosa, tunica muscularis and serosa showed patterns of development similar to those reported for the rumen and reticulum of red deer. The omasum of red deer during prenatal life, especially from 67 days of gestation, was shown to be an active structure with full secretory capacity. Its histological development, its secretory capacity (detected by the presence of neutral mucopolysaccharides) and its neuroendocrine nature (detected by the presence of positive non-neuronal enolase cells and the neuropeptides vasoactive intestinal peptide and neuropeptide Y) were parallel to the development of the rumen and the reticulum. However, its prenatal development was later than that of the omasum in sheep, goat and cow.

Morphometric and immunohistochemical study of the reticulum of red deer during prenatal development

Iberian red deer need to be conserved for their economic role and for their genetic importance as an important component of the ecosystem. Modifications currently being made to traditional management systems require a better understanding of the structure, function and development of their alimentary system. Here we describe a histomorphometric and immunohistochemical analysis of the stomach of 25 red deer embryos and fetuses from 30 days of gestation until birth (235 days). Differentiation of the reticular compartment from the primitive gastric tube begins at 67 days, forming a three-layered structure: epithelium, pluripotential blastemal tissue and serosa. The primitive reticular cells are initiated as small epithelial evaginations (primary ribs) at 117 days. At 142 days, lateral growths appear from the primary reticular ribs, forming the corneum papillae. The secondary reticular ribs form at 142 days as growths from the primary ribs. The uneven height of primary and secondary reticular ribs leads to the formation of cells of varying size. Growth of the reticular ribs involves the lamina propria but not the submucosa, so clear separation of these layers is maintained during histodifferentiation. Formation of the tunica muscularis from the pluripotential blastemal tissue begins at 67 days of intrauterine life, as two layers of longitudinally and circularly arranged myoblasts. Differentiation of the muscularis from the mucosa occurs at approximately 205 days, as longitudinal projections of the internal bundles of the tunica muscularis form the musculature of the primary ribs. The secretion of neutral and acid mucopolysaccharides by the reticular epithelial layer begins at 67 days, establishing the gradual adaptation of the mucosa to its protective function in postnatal life. Neuroendocrine (non-neuron enolase) and glial cells (glial fibrillary acidic protein and vimentin) were detected by immunohistochemistry, in a similar localization and intensity to that reported in the rumen. The neuropeptides vasoactive intestinal peptide and neuropeptide Y showed a positive immunoreaction in the reticular epithelium from 142 days of prenatal life, again earlier than reported for the rumen. In comparison with domestic ruminants, deer were shown to be less precocious with regard to development of gastric tube, in their capacity to secrete neutral mucopolysaccharides, and in their neuroendocrine nature, as determined by the detection of positive neuroendocrine and/or glial cells.

Characterisation of neurons expressing calbindin immunoreactivity in the ileum of the unweaned and mature sheep

We have identified the enteric neuron types expressing immunoreactivity for the calcium-binding protein calbindin D28k (CALB) in cryostat sections and whole-mount preparations of myenteric (MP) and submucosal (SMP) plexuses of sheep ileum. We wished to determine whether CALB-IR in the sheep enteric nervous system was expressed in Dogiel type II cells, as in guinea-pig and rat ileum, and could therefore be used as a marker for intrinsic primary afferent neurons. The neurochemical coding of CALB-containing myenteric and submucosal neurons in ileum of unweaned lamb and mature sheep and its co-localisation with various neural markers was studied immunohistochemically. An antiserum against neuronal nuclear protein (NeuN) failed to detect the entire neuronal population; it was expressed only in 48% of neuron-specific enolase (NSE)-immunoreactive (NSE-IR) neurons. Human neuronal protein appeared to occur in the large majority or all neurons. Almost all CALB-IR neurons were: (1) radially multidendritic; (2) eccentric multidendritic; (3) Dogiel type II. CALB-IR occurred in 20-25% of myenteric and 65-75% of submucosal neurons in lamb and mature sheep, with higher values in mature sheep. Nearly all CALB-IR neurons were common choline acetyltransferase (cChAT)-IR, whereas only about 20% of cChAT-IR somata were CALB-IR. In lamb and mature sheep, 90% of MP CALB-IR neurons were peripheral choline acetyltransferase (pChAT)-IR. In lamb SMP, 80+/-13% of CALB-IR cells were also pChAT-IR, whereas all those in mature SMP were pChAT-IR. Fewer myenteric CALB-IR neurons exhibited tachykinin (TK) in mature sheep (49%) than in lamb (88%). This was also the case for submucosal ganglia (mature sheep, 63%; lamb, 89%). In lamb MP, 77+/-7% of CALB-IR cells were NeuN-positive. In mature sheep, 73+/-10% of CALB-IR somata were NeuN-IR, but NeuN failed to stain SMP neurons. In the MP of suckling and mature sheep, Dogiel type II CALB-IR neurons were calcitonin gene-related peptide (CGRP)-IR. In the SMP at both stages, Dogiel type II CALB-IR somata (about 50% of CALB-IR neurons) were also CGRP-IR. Only small proportions of CALB-IR neurons showed immunoreactivity for calretinin or nitric oxide synthase (NOS), although large populations of CALB and NOS neurons occurred in the ganglia. Thus, CALB is a marker of most Dogiel type II neurons in the sheep but is not confined to Dogiel II neurons. CGRP is a more selective marker of Dogiel type II neurons, being only found in this neuron type.

Morphometric and immunohistochemical study of the rumen of red deer during prenatal development

Abstract A detailed study of the ontogenesis of deer stomach has not been undertaken to date, and our aim was to sequence several histological phenomena that occur during the ontogenesis of one of the gastric compartments, the rumen. Histomorphometric and immunohistochemical analyses were carried out on 50 embryos and fetuses of deer from the initial stages of prenatal life until birth. For the purposes of testing, the animals were divided into five experimental groups: group I, 1.4-3.6 cm crown-rump length, 30-60 days, 1-25% of gestation; group II, 4.5-7.2 cm crown-rump length, 67-90 days, 25-35% of gestation; group III, 8-19 cm crown-rump length, 97-135 days, 35-50% of gestation; group IV, 21-33 cm crown-rump length, 142-191 days, 45-70% of gestation; and group V, 36-40 cm crown-rump length, 205-235 days, 75-100% of gestation. The rumen of the primitive gastric tube was observed at approximately 60 days. At 67 days the rumen consisted of three layers: internal or mucosal, middle or muscular, and external or serosal layer. The stratification of the epithelial layer was accompanied by changes in its structure with the appearance of ruminal pillars and papillae. The outline of the ruminal papillae began to appear at 142 days of prenatal development as evaginations of the basal zone toward the ruminal lumen, pulling with it in its configuration the stratum basale, the lamina propria and the submucosa. From the pluripotential blastemic tissue at 60 days we witnessed the histodifferentiation of the primitive tunica muscularis, composed of two layers of myoblasts with a defined arrangement. It was also from the pluripotential blastemic tissue, at 97 days, that the lamina propria and the submucosa were differentiated. The serosa showed continuity in growth as well as differentiation, already detected in the undifferentiated outline phase. The tegumentary mucosa of deer rumen was shown without secretory capacity in the initial embryonic phases; neutral mucopolysaccharides appeared from 67 days. The presence of neuroendocrine cells (non-neuronal enolase) in the ruminal wall of deer during development was not detected until 97 days. The glial cells were detected at 142 days for glial fibrillary acidic protein and at 67 days for vimentin. The immunodetection of neuropeptides vasointestinal peptide and neuropeptide Y progressively increased with gestation period, starting from 97 days. In terms of the structure of the rumen of the primitive gastric tube, our observations revealed that the deer is less precocious than small and large domestic ruminants. Thus its secretory capacity, detected by the presence of neutral mucopolysaccharides, and its neuroendocrine nature, determined by the presence of positive non-neuronal enolase cells, were evident in more advanced stages of prenatal development than those detected in the sheep, goat and cow.

Nitric oxide-containing neurons in the bovine gut, with special reference to their relationship with VIP and galanin

The presence and distribution of nicotinamide dinucleotide phosphate diaphorase (NADPH-d)-containing neurons have been studied by means of NADPH-d histochemistry in different regions of the adult cow gut, from the esophagus to the rectum. NADPH-d and nitric oxide synthase (NOS) were constantly recognized to be colocalized in the same neuron. The colocalization of vasoactive intestinal polypeptide (VIP) and galanin in such nitrergic neurons was also studied by means of combined histochemical and immunofluorescence techniques. NADPH-d-positive neurons were present along the myenteric plexus of the entire gut, and in the submucous plexus from the abomasum to the rectum. Notably, they formed two types of nerve networks in the submucous connective tissue of the jejunum-ileum. NADPH-d-positive innervation of the muscle layers occurred throughout the tract, and sometimes a clear correspondence was noted between the number of reactive fibres and the thickness of the muscle. Nitrergic fibres also occurred in the mucosa and often were in relation to glands and blood vessels. The nitrergic neurons varied in size, shape, and intensity of staining, and often their terminals were seen to surround unstained perikarya. Various types of neurons were recognized on the basis of their chemical content; one of them contained galanin, VIP and NOS simultaneously. The present results suggest that the nitrergic neurons of the bovine gastrointestinal tract play roles presumably for controlling the motility of the gut and the conduction of interneuronal impulses.

Structural differences of the enteric nervous system in the cattle forestomach revealed by whole mount immunohistochemistry

The specific motility patterns of the forestomach of ruminants, composed of three structurally distinct compartments (rumen, reticulum, omasum), require an elaborate intramural innervation. To demonstrate the complex structure of the enteric nervous system (ENS), whole mount preparations obtained from different sites of the bovine forestomach were submitted to immunohistochemical procedures in which neuronal (protein gene product 9.5, neurofilament 200) and glial (protein S-100, glial fibrillary acid protein) markers were applied. Immunohistochemistry performed on whole mounts allowed a detailed two-dimensional assessment of the architecture of the intramural nerve networks. Generally, the myenteric and submucosal plexus layers were composed of ganglia and interconnecting nerve fiber strands, whereas the mucosal plexus consisted of an aganglionated nerve network. However, the texture of the ENS showed considerable regional differences concerning the ganglionic size, shape and density and the arrangement of nerve fiber strands. The myenteric plexus of the ruminal wall, showing a low ganglionic density and wide polygonal meshes, contrasted with the nerve network within the ruminal pillar which consisted of ropeladder-like nerve fiber strands and parallel orientated ganglia. The highest ganglionic density was observed at the reticular groove, the most prominent ganglia were found within the omasal wall. Branches of the vagal nerve frequently ramified within the myenteric plexus layers. The submucosal plexus of the rumen was divided into an external and internal layer; the reticular submucosal plexus followed the cristae and cellulae reticuli, the omasal submucosal (sublaminar) plexus showed intra- and parafascicular ganglia apart from ganglia located at the junctions of the nerve network. The mucosal plexus of the rumen consisted of thin nerve fascicles ramifying between the ruminal papillae, and reticular mucosal nerve fibers passed throughout the base of the cellulae reticuli. The highly specialised nerve network of the intralaminar omasal plexus showed radial and transverse trajectories reflecting the spatial arrangement of the intralaminar musculature. The demonstrated structural complexity of the ENS reflects the functional complexity of the ruminant forestomach and indicates the relatively high degree of autonomy in coordinating the different motility patterns required for the processing of the ingesta.

Morphological study of the submucosal and mucosal plexuses of the sheep forestomach

Submucosal and mucosal nerve plexuses in the ovine forestomach were examined by immunohistochemical staining for protein gene-product 9.5 (PGP 9.5) and for S-100 protein (S-100), using whole-mount specimens that had been prepared by treatment with KOH. Nerve fibers of various sizes and glial cells (i.e., Schwann cells and satellite cells) were stained with antibodies against PGP 9.5 and S-100 respectively. The network of the submucosal plexus in the rumen is irregular and some nerve bundles in the plexus cross over other bundles. Some of the nerve bundles penetrate the ruminal papillae. The submucosal plexus in the reticulum consists of a network in the reticular wall and the reticular folds. The submucosal plexus in the omasum is also divided into two segments; namely, the sublaminar and the intralaminar plexuses. Most of the submucosal ganglion cells are unipolar and smooth-surfaced, being located singly or in small groups. A few perikarya were detected in the ruminal papillae. The number of perikarya per unit surface area is greater in the caudal portion of the omasal lamina (19.32 +/- 8.62 per cm2). In the mucosal plexuses, a well-developed network of beaded fibers with PGP 9.5-like immunoreactivity and a glial framework of S-100 like immunoreactivity was observed, in particular in the ruminal, reticular and omasal papillae. The intrapapillary nervous networks are interconnected by thin bundles of nerves in the interpapillary region. The present results suggest that some of the mucosal functions are intrinsically regulated by the submucosal and mucosal plexuses in the ovine forestomach.