title: Immunohistochemical study of the digestive tract of Oligosarcus hepsetus.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro 23890-000, Brazil. dmjvieira@hotmail.com
authors.forename: Danielle A
authors.initials: DA
authors.lastname: Vieira-Lopes
authors.forename: Nadja L
authors.initials: NL
authors.lastname: Pinheiro
authors.forename: Armando
authors.initials: A
authors.lastname: Sales
authors.forename: Adriana
authors.initials: A
authors.lastname: Ventura
authors.forename: Francisco G
authors.initials: FG
authors.lastname: Araújo
authors.forename: Iracema D
authors.initials: ID
authors.lastname: Gomes
authors.forename: Aparecida A
authors.initials: AA
authors.lastname: Nascimento
mesh_terms: D000818:Animals; D060126:Characidae / Q000033:anatomy & histology* / Q000378:metabolism; D019858:Enteroendocrine Cells / Q000166:cytology* / Q000378:metabolism; D005247:Feeding Behavior; D041981:Gastrointestinal Tract / Q000033:anatomy & histology* / Q000378:metabolism; D007150:Immunohistochemistry
keywords: Endocrine cells; Esophagus; Fish; Intestine; Stomach