Abstract
The stomach of Rhinella icterica was analyzed at light microscopy, employing histochemical techniques, lectin histochemistry, and immunohistochemistry for identifying enteroendocrine cells (EC). Although the stomach was composed of fundic and pyloric regions, its wall is formed by mucosa, submucosa, muscularis, and serosa. The mucosa was lined by a simple columnar mucous epithelium, supported by loose connective tissue. Several tubular, simple glands were composed of mucous neck cells, containing oxynticopeptic cells and EC cells. The mucous neck cells were rich in neutral glycoconjugates. The oxynticopeptic cells were predominant in fundic glands, exhibiting weaker alcianophilic reaction at their apical cytoplasm. Serotonin (5-HT) immunoreactive (IR) cells occurred throughout the entire stomach, preferentially located among mucous cells at upper part of the fundic glands. The muscularis mucosae, formed of smooth muscle, separated the mucosal layer from the submucosa, both of which were constituted by loose connective tissue, but without glands. Lymphoid modules occurred in the mucosa at the boundary at the stomach and the gut. In addition, the muscularis was constituted by two sublayers, the circular internal and the longitudinal external, being recovered by the connective tissue of the serosa.
Highlights
The structural organization of a tissue and/or an organ represents a close association between life habits and physiology of the animal; the tissue structure can reflect their lifestyle and provide information for understanding the population declination and fluctuations [1, 2].Morphological studies on the anuran gastrointestinal tube have been performed by histochemical [3,4,5], ultrastructural [6], and immunohistochemical techniques [7, 8], showing histological peculiarities to the stomach
The mucosubstances, which phylogenetically first appeared in mucous neck cells of the gastric glands of anurans [12], have already been reported for Rana aurora aurora [13], Bufo viridis [14], Rana perezi [15], Bufo melanostictus [3], and Bufo marinus [16], indicating variability among anuran species
The mucosa showed gastric folds, and it was made of the lining epithelium supported by the lamina propria of loose connective tissue (Figure 1)
Summary
Morphological studies on the anuran gastrointestinal tube have been performed by histochemical [3,4,5], ultrastructural [6], and immunohistochemical techniques [7, 8], showing histological peculiarities to the stomach. These differences are more evident considering mainly the exocrine gastric glands, whose morphology varies according to the gastric region. The gastric surface is recovered by a thin biofilm of mucous that is secreted by superficial mucous and mucous neck cells [9] This mucous layer forms a highly viscous barrier that protects the stomach surface, being formed by acid and neutral glycoconjugates. Different types of carbohydrates were identified in secretory cells in the stomach of Bufo viridis [17, 18] and Rana esculenta [19]
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