SUMMARY:The ontogenesis of the gastroesophageal mucosa involves morphological alterations related to its structure and the function of each segment. The present study describes the histogenesis of the mucus-secreting epithelium and glands of the esophagus, gizzard, and proventriculus of the chicken (Gallus gallus), and identifies alterations in the secretion pattern of glycosaminoglycans (GAG's). We analyzed 38 chicken embryos, processed the material collected following the histological routine, and then stained it with hematoxylin-eosin for the analysis of tissue structure and with Gomori's trichrome for the identification of conjunctive tissue and collagen fibers. We used the PAS histochemical technique for the analysis of neutral GAG's and the AB pH 2.5 histochemical technique for the analysis of acid GAG's. The embryos at late stage of development had the esophagus wall composed of four layers: mucosa, submucosa, muscularis, and serosa, whereas the proventriculus and the gizzard were composed of three layers: mucosa, muscularis, and serosa. In all three segments, we identified the superficial epithelium as mucus-secreting; in the esophagus this epithelium was mucussecreting only at the initial development stages. The proventricular glands began to form at the initial development stages, whereas the tubular glands began to form in the gizzard just after the 15th day. The differences in the production of GAG's in these regions of the digestive tract are related to development stages, functions, and physiological requirements of each segment, and to the gradual adjustment of the body to the post-hatching life.

AIM:To describe the histology of the digestive tract and to investigate the occurrence of endocrine cells in Oligosarcus hepsetus (O. hepsetus ). METHODS:The digestive tract (DT) of O. hepsetus was divided into esophagus, two stomach regions (glandular and non-glandular) and two intestinal regions (anterior and posterior). These specimens were processed by routine histological techniques and stained with hematoxylin-eosin, Gomori's trichrome, periodic acid Schiff (PAS) and Alcian blue (AB). An immunohistochemical method using avidin-biotin-peroxidase was employed. RESULTS:The esophagus is lined with a non-keratinized stratified squamous epithelium that is reactive to PAS and AB. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells that are reactive only to PAS. The intestine has a simple columnar epithelium with a brush border and goblet cells that are reactive to PAS and AB. Somatostatin, serotonin and cholecystokinin immunoreactive cells were identified throughout the DT. CONCLUSION:This study revealed adaptations for the species' diet and showed that the distribution and relative frequency of immunoreactive cells are similar to those of other fish.

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. Juiz de Fora, Minas Gerais, Brasil. bernadete.sousa@ufjf.edu.br. RESUMOPhrynops geoffroanus é o quelônio onívoro com mais ampla distribuição geográfica na América do Sul. Este trabalho descreve a histologia e histoquímica do tubo digestório desta espécie, relacionando as características dos órgãos com seu hábito alimentar. O esôfago, estômago e intestino de quatro espécimes foram fixados em formol 10% e incluídos em parafina por técnica histológica de rotina. Depois, cortes de 5 μm de espessura foram corados com hematoxilina-eosina (HE), ácido periódico de Schiff (PAS) e alcian blue (AB) pH 0.4 e 2.5. O tubo é formado pelas camadas mucosa, submucosa, muscular e adventícia ou serosa. A mucosa do esôfago e do estômago é revestida pelo epitélio simples cilíndrico com células mucossecretoras, onde estão inseridas glândulas intraepiteliais na porção do esôfago e fossetas gástricas desembocando em glândulas no estômago. O estômago divide-se em anterior, médio e posterior, de acordo com a profundidade das fossetas e a concentração de glândulas gástricas. O intestino é revestido pelo epitélio simples cilíndrico com borda estriada e células caliciformes e divide-se em anterior e posterior, de acordo com o padrão de dobramentos da mucosa e o número de células caliciformes. Reatividade ao PAS e AB é observada em todo o tubo. Fibras musculares lisas estão presentes na camada mucosa de todos os segmentos. A camada muscular é formada por duas subcamadas de músculo liso, exceto na porção posterior do estômago. Este estudo ajudará no entendimento da fisiologia digestiva da espécie investigada e fornecerá dados para análises comparativas com outros quelônios. PALAVRAS CHAVES: Réptil, esôfago, estômago, intestino, células mucossecretoras. Histology and histochemistry of the digestive tract of Phrynops geoffroanus (Testudines, Chelidae)ABSTRACT Phrynops geoffroanus is the omnivorous chelonian with widest geographical distribution in South America. This work describes the histology and histochemistry of the digestive tube of this species, to relate the characteristics of these organs to the species' eating habit. The esophagus, stomach and intestine of four specimens were fixed in 10% formal and embedded in paraffin by routine histological techniques. Afterwards, 5-μm sections were stained with hematoxylin-eosin (HE), periodic acid-Schiff (PAS) and alcian blue (AB) pH 0.4 and 2.5. The tube is formed by the mucosa, submucosa, muscular and adventitia or serosa layers. The mucosa layer of the esophagus and stomach is lined with a simple cylindrical epithelium with mucus-secreting cells, where are intraepithelial glands inserted in the portion of the esophagus and gastric fossettes emptying into glands in the stomach. The stomach is divided into an anterior, middle and posterior region, according to the depth of the fossettes and the concentration of gastric glands. The intestine is lined by a simple cylindrical epithelium with striated boundaries and goblet cells and is divided into an anterior and posterior regions, according to th...

Conjoined twinning is an embryological anomaly rarely reported in wild mammals and with only two previous records in Chiroptera. Here, we report a case of dicephalic parapagus conjoined twins in the Neotropical phyllostomid genus Artibeus. These twins are males and present separated heads and necks, but a conjoined trunk with an expanded upper thoracic region. They developed two complete forelimbs and two complete hindlimbs, all laterally to the trunk. There is a volume in the upper midback and between the heads that resembles a third rudimentary medial forelimb, but X-ray images only suggest the presence of medial skeletal elements of the pectoral girdle (clavicle and scapulae) in this region. The X-ray images also show that vertebral columns run separated from head until the base of lumbar region, where they form a single structure. Using ultrasound images, we detected the presence of two similarly sized and apparently separated hearts. The accumulation of study cases like this will help in the understanding of patterns and process behind this phenomena, and collection material plays a key role in this context.