Morphological, morphometric and histochemical characterization of the gastric mucosa of the camel (Camelus dromedarius)

Age-dependent changes in the anatomical and histological characteristics of the aggregated lymphoid nodules in the stomach of Dromedary camels (Camelus Dromedarius)

Gastrointestinal associated lymphoid tissue (GALT) is an important component of the mucosal immune system. It is the largest mass of lymphoid tissues in the body and makes up more than 70% immune cells of entire body. GALT is considered to be the origin of systemic mucosal immunity and consists of solitary lymphoid nodules, aggregated lymphoid nodules (Peyer's patches, PPs), scattered lymphoid tissues, and follicular associated epithelia. PPs play important roles as antigen inductive sites of the mucosal immune system, which are mainly distributed in the intestine of animals and humans (especially ileum and appendix). However, a special area of well-developed aggregated lymphoid nodules in the abomasum of Dromedary camel was found in our laboratory. Its existence was rarely described in the stomach before. In the present study, we investigated this special structure with the dromedary camels of different ages (young, 0.5-2 years; pubertal, 3-5 years; middle-aged, 6-16 years; old, 17-20 years), by the anatomical, histological and immunohistochemical approaches. The results showed that the special structure was mainly distributed in the cardiac glandular area of the abomasum, forming a triangular area. The mucosal folds in this area were significantly thicker than those in the surrounding region. These mucosal folds had two different forms, namely reticular mucosal folds (RMF) and longitudinal mucosal folds (LMF). There were abundant lymphoid nodules in the submucosa of RMF and LMF, which were arranged in one or multiple rows. The statistical analysis of the height and thickness of RMF and LMF showed that the structure was most developed in pubertal dromedary camels. The histological characteristics of the structure were the same as PPs in the intestine of the Dromedary camel, while anatomical appearance showed some difference. The immunohistochemical examination revealed that both immunoglobulin A (IgA) and G (IgG) antibodies-producing cells (APCs) were extensively distributed in the gastric lamina propria (LP) in all age group. Our finding suggest that camel stomach not only performs digestive functions, but also involves parts of body immunity.

Histomorphometric and histochemical characteristics of the oesophagus of the greater mouse-eared Bat, Myotis myotis (Borkhausen, 1797)

The aim of this study was to examine the histomorphometric and histochemical structure of oesophagus of the wild-caught greater mouse-eared bat M. myotis. For this purpose, 10 specimens of oesophagus were collected and processed. The oesophagus wall of M. myotis is composed of four layers: tunica mucosa, tunica submucosa, tunica muscularis and tunica adventitia. The mucosa is covered by a non-keratinized stratified squamous epithelium. There were no glands in the wall of the oesophagus. Tunica muscularis is composed of two muscle layers: internal circular muscular layer and an external longitudinal muscular layer. Histochemical studies revealed that the oesophagus was AB/PAS and PAS positive indicating the presence of acidic and neutral mucosubstances. AB-PAS staining shows that glycoproteins were predominant in the all examined layers of the oesophagus. Because of the absence of oesophageal glands in M. myotis, positive reaction with AB-PAS staining may be due to secretion of salivary glands. Absence of oesophageal glands reflects the functional adaptation as high food passage rate for the insectivorous feeding habits of animals.

Effects of long-term dehydration on oxidative stress, apoptotic markers and neuropeptides in the gastric mucosa of the dromedary camel

We investigated the effects of 20 days of dehydration and 20 days of dehydration followed by 72 h of rehydration on the gastric mucosa of the one-humped dromedary camel. The parameters addressed include biomarkers of oxidative stress, apoptosis, gastric epithelial histology, gastric neuropeptides, and their receptors. Nineteen clinically healthy, 4-5 year-old male dromedary camels were divided into three groups (five control camels, eight dehydrated for 20 days, six dehydrated for 20 days and then rehydrated for 72 h). Dehydration affected the oxidative stress biomarkers causing a significant increase in malondialdehyde, glutathione, nitric oxide, and catalase values compared with controls. Also the results revealed that dehydration caused different size cellular vacuoles and focal necrosis in the gastric mucosa. Rehydration for 72 h resulted in improvement in some parameters but was not enough to fully abolish the effect of dehydration. Dehydration caused significant increase in apoptotic markers; tumor necrosis factor α, caspases 8 and 3, BcL-x1 and TGFβ whereas caspase 9, p53, Beclin 1, and PARP1 showed no significant change between the three groups indicating that apoptosis was initiated by the extrinsic pathway. Also there were significant increases in prostaglandin E2 receptors and somatostatin in plasma and gastric epithelium homogenate, and a significant decrease in cholecystokinin-8 receptors. A significant decrease of hydrogen potassium ATPase enzyme activity was also observed. Pepsinogen C was not affected by dehydration. It is concluded that long-term dehydration induces oxidative stress and apoptosis in camel gastric mucosa and that camels adjust gastric functions during dehydration towards water economy. More than 72 h are needed before all the effects of dehydration are reversed by rehydration.

The Distribution of SIgA and IgG Antibody-Secreting Cells in the Small Intestine of Bactrian Camels (Camelus bactrianus) of Different Ages

Secretory immunoglobulin A (SIgA) and immunoglobulin G (IgG) antibody-secreting cells (ASCs) are two important cell types in the mucosal immune system. This study aimed to explore the distribution of these ASC populations in the small intestine of Bactrian camels of different ages. Twenty-four Alashan Bactrian camels were divided into the following four age groups: young (1–2 years), pubertal (3–5 years), middle-aged (6–16 years) and old (17–20 years). SIgA and IgG ASCs in the intestinal mucosa lamina propria (LP) were observed and analyzed using immunohistochemcal techniques. The results from all age groups show that both SIgA and IgG ASCs were diffusely distributed in the intestinal LP, and some cells aggregated around the crypts. Moreover, the densities of the two ASC populations gradually increased from the duodenum to the jejunum and then decreased in the ileum. Meanwhile, there were more SIgA ASCs than IgG ASCs in the duodenum, jejunum, and ileum, and these differences were significant in the young and pubertal groups (P<0.05). In addition, the SIgA and IgG ASC densities increased from the young to the pubertal period, peaked at puberty, and then gradually decreased with age. The results demonstrate that the SIgA and IgG ASC distributions help to form two immunoglobulin barriers in the intestinal mucosa to provide full protection, helping to maintain homeostasis. These findings also underscore the importance of researching the development and degeneration of intestinal mucosal immunity in Bactrian camels.

Comparative gastric morphometry of Muong indigenous and Vietnamese wild pigs

It is hypothesized that despite sharing a similar habitat, the Muong indigenous and Vietnamese wild pigs may reveal different gastric morphology. Due to the protective nature of procuring these pigs, a total of 12 Muong indigenous pigs and nine Vietnamese wild pigs stomach collected post mortem were analysed for selected biometric parameters and histology. The result indicated that the stomach of the Vietnamese wild pig is broader with a bigger capacity and greater proportion of proper gastric glands. Interestingly, the stomach mass correlated well with live body weight in both breeds apart from possessing similar histomorphometry of the gastric gland regions. On the other hand, the thicker (P < 0.05) submucosa in the Vietnamese wild pig is attributed to the presence of numerous loose connective tissues, abundant blood vessels, adipose tissues and nerve plexus. The appearance of lymphoid follicles underneath the tubular gastric glands in the Vietnamese wild pig exceeded that of Muong indigenous pigs. This finding suggested that the difference in feeding behavior as well as immunity. In conclusion, adaptations found in the Vietnamese wild pig indicated that this breed is equipped with a bigger and effectively functional stomach to suit its digestive physiology and immunity in the wild.