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. 1. Introduction The structural organization of a tissue and/or an organ represents a close association between life habits and physiology of the animal; thus, 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 [3–5], 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. In mammals, the stomach is made up of mucosa, submucosa, muscularis, and adventitia or serosa. 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. Histochemical studies indicate differences regarding the qualitative expression of neutral, sulfated, and carboxylated mucosubstances [10, 11]. The mucosubstances, which phylogenetically first appeared in mucous neck cells of the gastric glands of anurans [12], have
References
[1]
A. M. Anderson, D. A. Haukos, and J. T. Anderson, “Diet composition of three anurans from the playa wetlands of Northwest Texas,” Copeia, no. 2, pp. 515–520, 1999.
[2]
G. Menghi, L. Marchetti, M. G. Sabbieti, M. Menghi, and S. Materazzi, “In situ visualization of o-phthalate esters in gastrointestinal tract of the frog Rana esculenta,” Histology and Histopathology, vol. 18, no. 2, pp. 371–377, 2003.
[3]
S. K. Loo and W. C. Wong, “Histochemical observations on the mucins of the gastrointestinal tract in the toad (Bufo melanostictus),” Acta Anatomica, vol. 91, no. 1, pp. 97–103, 1975.
[4]
G. Bani, L. Formigli, and R. Cecchi, “Morphological observations on the glands of the oesophagus and stomach of adult Rana esculenta and Bombina variegata,” Italian Journal of Anatomy and Embryology, vol. 97, no. 2, pp. 75–87, 1992.
[5]
J. Rovira, A. C. Villaro, M. E. Bodegas, E. Valverde, and P. Sesma, “Structural study of the frog Rana temporaria larval stomach,” Tissue and Cell, vol. 25, no. 5, pp. 695–707, 1993.
[6]
T. Ogata and Y. Yamasaki, “Ultra-high-resolution scanning electron microscopy of the continuity of cytoplasmic and luminal membranes in frog oxyntic cells,” The Anatomical Record, vol. 245, no. 3, pp. 559–567, 1996.
[7]
A. A. Pelli-Martins, C. Machado-Santos, A. Sales, and L. de Brito-Gitirana, “Histochemical, immunohistochemical, and ultrastructural observations of the esophagus morphology of Rinella icterica (Anuran, Bufonidae),” Acta Zoologica, vol. 93, no. 4, pp. 373–380, 2012.
[8]
M. El-Salhy, L. Grimelius, E. Wilander, G. Abu-Sinna, and G. Lundqvist, “Histological and immunohistochemical studies of the endocrine cells of the gastrointestinal mucosa of the toad (Bufo regularis),” Histochemistry, vol. 71, no. 1, pp. 53–65, 1981.
[9]
A. L. Kierszenbaum and L. L. Tres, Histology and Cell Biology: An Introduction to Pathology, Elsevier Saunders, Philadelphia, Pa, USA, 2012.
[10]
D. Ferri, G. E. Liquori, and G. Scillitani, “Morphological and histochemical variations of mucous and oxynticopeptic cells in the stomach of the seps, Chalcides chalcides,” Journal of Anatomy, vol. 194, no. 1, pp. 71–77, 1999.
[11]
D. G. Sheahan and H. R. Jervis, “Comparative histochemistry of gastrointestinal mucosubstances,” The American Journal of Anatomy, vol. 146, no. 2, pp. 103–131, 1976.
[12]
T. Suganuma, T. Katsuyama, M. Tsukahara, M. Tatematsu, Y. Sakakura, and F. Murata, “Comparative histochemical study of alimentary tracts with special reference to the mucous neck cells of the stomach,” American Journal of Anatomy, vol. 161, no. 2, pp. 219–238, 1981.
[13]
D. Ferri, G. E. Liquori, L. Natale, G. Santarelli, and G. Scillitani, “Mucin histochemistry of the digestive tract of the red-legged frog Rana aurora aurora,” Acta Histochemica, vol. 103, no. 2, pp. 225–237, 2001.
[14]
G. E. Liquori, G. Scillitani, M. Mastrodonato, and D. Ferri, “Histochemical investigations on the secretory cells in the oesophagogastric tract of the Eurasian green toad, Bufo viridis,” The Histochemical Journal, vol. 34, no. 10, pp. 517–524, 2002.
[15]
J. Gallego-Huidobro and L. M. Pastor, “Histology of the mucosa of the oesophagogastric junction and the stomach in adult Rana perezi,” Journal of Anatomy, vol. 188, no. 2, pp. 439–444, 1996.
[16]
M.-C. Ruiz, A. Acosta, M. J. Abad, and F. Michelangeli, “Nonparallel secretion of pepsinogen and acid by gastric oxyntopeptic cells of the toad (Bufo marinus),” The American Journal of Physiology—Gastrointestinal and Liver Physiology, vol. 265, no. 5, pp. G934–G941, 1993.
[17]
D. Ferri and G. E. Liquori, “Characterization of secretory cell glycoconjugates in the alimentary tract of the ruin lizard (Podarcis sicula campestris) by means of lectin histochemistry,” Acta Histochemica, vol. 93, no. 1, pp. 341–349, 1992.
[18]
D. Ferri and G. E. Liquori, “Immunohistochemical investigations on the pyloric glands of the ruin lizard (Podarcis sicula campestris de Betta),” Acta Histochemica, vol. 96, no. 1, pp. 96–103, 1994.
[19]
M. Mastrodonato, G. Calamita, R. Rossi, G. Scillitani, G. E. Liquori, and D. Ferri, “Expression of H+,K+-ATPase and glycopattern analysis in the gastric glands of Rana esculenta,” Journal of Histochemistry & Cytochemistry, vol. 57, no. 3, pp. 215–225, 2009.
[20]
T. Shirakawa and B. I. Hirschowitz, “Interaction between stimuli and their antagonists on frog esophageal peptic glands,” The American Journal of Physiology—Gastrointestinal and Liver Physiology, vol. 249, no. 6, pp. G668–G673, 1985.
[21]
M. C. Ruiz, M. J. Abad, B. González, A. Acosta, and F. Michelangeli, “Comparison of acid and pepsinogen secretion control by oxyntopeptic cell of amphibians,” Acta Cientifica Venezolana, vol. 44, no. 2, pp. 89–94, 1993.
[22]
G. E. Liquori, S. Zizza, M. Mastrodonato, G. Scillitani, G. Calamita, and D. Ferri, “Pepsinogen and H,K-ATPase mediate acid secretion in gastric glands of Triturus carnifex (Amphibia, Caudata),” Acta Histochemica, vol. 107, no. 2, pp. 133–141, 2005.
[23]
M. A. Tzaneva, “Ultrastructural immunohistochemical localization of gastrin, somatostatin and serotonin in endocrine cells of human antral gastric mucosa,” Acta Histochemica, vol. 105, no. 2, pp. 191–201, 2003.
[24]
S. K. Ku, H. S. Lee, and J. H. Lee, “An immunohistochemical study of the gastrointestinal endocrine cells in the C57BL/6 mice,” Anatomia Histologia Embryologia, vol. 32, no. 1, pp. 21–28, 2003.
[25]
C. Fink, M. Tatar, K. Tatar, R. Hospes, M. Kressin, and K. Klisch, “Serotonin-containing cells in the gastrointestinal tract of newborn foals and adult horses,” Journal of Veterinary Medicine Series C: Anatomia Histologia Embryologia, vol. 35, no. 1, pp. 23–27, 2006.
[26]
C. M. Santos, A. A. Nascimento, A. L. Peracchi, D. Dias, T. P. Ribeiro, and A. Sales, “A comparative immunohistochemical study of endocrine cells in the digestive tract of two frugivorous bats: Artibeus cinerius and Sturnira lilium,” Acta Histochemica, vol. 110, no. 2, pp. 134–142, 2008.
[27]
K. Sugimoto, Y. Ichikawa, and I. Nakamura, “Peroxidase activity in the epithelium of the digestive tract of the bullfrog, Rana catesbeiana,” The Journal of Experimental Zoology, vol. 233, no. 2, pp. 209–219, 1985.
[28]
O. D. De Rada, P. Sesma, and J. J. Vazquez, “Endocrine cells of the gastric mucosa of Rana temporia L,” Histology and Histopathology, vol. 2, no. 2, pp. 119–128, 1987.
[29]
G. Wang, Y. Wang, D. Ma et al., “Five novel antimicrobial peptides from the Kuhl's wart frog skin secretions, Limnonectes kuhlii,” Molecular Biology Reports, vol. 40, no. 2, pp. 1097–1102, 2013.
[30]
J. M. Conlon and A. Sonnevend, “Antimicrobial peptides in frog skin secretions,” Methods in Molecular Biology, vol. 618, pp. 3–14, 2010.
[31]
H. S. Kim, H. Yoon, I. Minn, et al., “Pepsin-mediated processing of the cytoplasmic histone H2A to strong antimicrobial peptide buforin I,” The Journal of Immunology, vol. 165, no. 6, pp. 3268–3274, 2000.
[32]
I. Minn, H. S. Kim, and S. C. Kim, “Antimicrobial peptides derived from pepsinogens in the stomach of the bullfrog, Rana catesbeiana,” Biochimica et Biophysica Acta—Molecular Basis of Disease, vol. 1407, no. 1, pp. 31–39, 1998.
[33]
J. H. Cho, B. H. Sung, and S. C. Kim, “Buforins: histone H2A-derived antimicrobial peptides from toad stomach,” Biochimica et Biophysica Acta—Biomembranes, vol. 1788, no. 8, pp. 1564–1569, 2009.
[34]
R. D. Lillie and H. M. Fullmer, Histopathologic Technique and Practical Histochemistry, MacGraw-Hill, New York, NY, USA, 4th edition, 1976.
[35]
J. A. Kiernan, Histological & Histochemical Methods-Theory and Practice, Pergamon Press, Frankfurt, Germany, 2nd edition, 1990.
[36]
D. I. Patt and G. R. Patt, Comparative Vertebrate Histology, Harper & Row, New York, NY, USA, 1969.
[37]
R. Paniagua and M. Nista, Introducción a la Histologia Animal Comparada, Labor, Barcelona, Spain, 1983.
[38]
J. L. Norris, “The normal histology of the esophageal and gastric mucosae of the frog, Rana pipiens,” The Journal of Experimental Zoology, vol. 141, no. 1, pp. 155–173, 1959.
[39]
D. M. Smith, R. C. Grasty, N. A. Theodosiou, C. J. Tabin, and N. M. Nascone-Yoder, “Evolutionary relationships between the amphibian, avian, and mammalian stomachs,” Evolution and Development, vol. 2, no. 6, pp. 348–359, 2000.
[40]
M. Derrien, M. van Passel, J. van de Bovenkamp, R. Schipper, W. M. de Vos, and J. Dekker, “Mucin-bacterial interactions in the human oral cavity and digestive tract,” Gut Microbes, vol. 1, no. 4, pp. 254–268, 2010.
[41]
W. D. Kuhlmann, P. Peschke, and K. Wurster, “Lectin-peroxidase conjugates in histopathology of gastrointestinal mucosa,” Virchows Archiv A Pathological Anatomy and Histology, vol. 398, no. 3, pp. 319–328, 1983.
[42]
C. M. Santos, S. Duarte, T. G. Sousa, T. P. Ribeiro, A. Sales, and F. G. Araújo, “Histologia e caracteriza？？o histoquímica do tubo gastrintestinal de Pimelodus macu latus (Pimelodidae, Siluriformes) no reservatório de Funil, Rio de Janeiro, Brasil,” Iheringia, vol. 97, pp. 78–82, 2007.
[43]
G. E. Liquori, M. Mastrodonato, S. Zizza, and D. Ferri, “Glycoconjugate histochemistry of the digestive tract of Triturus carnifex (Amphibia, Caudata),” The Journal of Molecular Histology, vol. 38, no. 3, pp. 191–199, 2007.
[44]
A. E. Fry and J. C. Kaltenbach, “Histology and lectin-binding patterns in the digestive tract of the carnivorous larvae of the anuran, Ceratophrys ornata,” Journal of Morphology, vol. 241, pp. 19–32, 1999.
[45]
G. Scillitani, D. Mentino, G. E. Liquori, and D. Ferri, “Histochemical characterization of the mucins of the alimentary tract of the grass snake, Natrix natrix (Colubridae),” Tissue and Cell, vol. 44, no. 5, pp. 288–295, 2012.
[46]
P. Peschke, W. D. Kuhlmann, and K. Wurster, “Histological detection of lectin binding sites in human gastrointestinal mucosa,” Experientia, vol. 39, no. 3, pp. 286–287, 1983.
[47]
M. Ito, K. Takata, S. Saito, T. Aoyagi, and H. Hirano, “Lectin-binding pattern in normal human gastric mucosa—a light and electron microscopic study,” Histochemistry, vol. 83, no. 4, pp. 189–193, 1985.
[48]
N. Kessimian, B. J. Langner, P. N. McMillan, and H. O. Jauregui, “Lectin binding to parietal cells of human gastric mucosa,” Journal of Histochemistry and Cytochemistry, vol. 34, no. 2, pp. 237–243, 1986.
[49]
G. E. Liquori, D. Ferri, and G. Scillitani, “Fine structure of the oxynticopeptic cells in the gastric glands of the ruin lizard, Podarcis sicula campestris (De Betta , 1857),” The Histochemical Journal, vol. 243, no. 2, pp. 167–171, 2000.
[50]
W. Straus, “Mannose-specific binding sites for horseradish peroxidase in various cells of the rat,” Journal of Histochemistry and Cytochemistry, vol. 31, no. 1, pp. 78–84, 1983.
[51]
M. Yoshida, “A light microscope study of the distribution of muscle in the frog esophagus and stomach,” Journal of Smooth Muscle Research, vol. 37, no. 3-4, pp. 95–104, 2001.
[52]
H. E. Raybould, J. Glatzle, C. Robin et al., “Expression of 5-HT3 receptors by extrinsic duodenal afferents contribute to intestinal inhibition of gastric emptying,” The American Journal of Physiology—Gastrointestinal and Liver Physiology, vol. 284, no. 3, pp. G367–G372, 2003.
[53]
A. C. Villaro, J. Rovira, M. E. Bodegas, M. A. Burrell, D. García-Ros, and P. Sesma, “Immunocytochemical and ultrastructural characterization of endocrine cells in the larval stomach of the frog Rana temporaria tadpoles: a comparison with adult specimens,” Tissue and Cell, vol. 33, no. 5, pp. 462–477, 2001.
[54]
A. L'Hermite, J. Hourdry, and R. Ferrand, “Investigations of endocrine cells in the gastrointestinal tract and pancreas during the metamorphosis of an anuran (Alytes obstetricans L.): histochemical detection of APUD cells,” General and Comparative Endocrinology, vol. 69, no. 3, pp. 381–390, 1988.
