Original Articles
Copyright ©The Author(s) 2000. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 15, 2000; 6(1): 96-101
Published online Feb 15, 2000. doi: 10.3748/wjg.v6.i1.96
Immunocytochemical identification and localization of APUD cells in the gut of seven stomachless teleost fishes
Qian-Sheng Pan, Zhi-Ping Fang, Ya-Xin Zhao
Qian-Sheng Pan, College of Fisheries, Huazhong Agricultural University, Wuhan 43 0070, Hubei Province, China
Zhi-Ping Fang, Ya-Xin Zhao, College of Animal Husbandry and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei Province, China
Qian-Sheng Pan, male, born on 1943-11-18 in Dushan City, Guizhou Prov ince, Han nationality, Graduated from Shanghai Fisheries University in 1968, Pro fessor of Ichthyology, major in studies on animal immunocytochemistry, having mo re than 50 papers published. Presented at the International Conference on Gastrointestinal Hormones a nd Gastrointestinal Motility, Beijing, 26-28 October, 1993 and the 4th China-J apan Histochemistry and Cytochemistry Symposium, Chongqing, 21-24 September, 1996.
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China. No. 39070 666.
Correspondence to: Prof. Zhi-Ping Fang, College of Animal Husba ndry and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hu bei, China
Telephone: +86-27-87393766-2466 Fax: +86-27-87396057
Received: May 21, 1999
Revised: July 22, 1999
Accepted: August 1, 1999
Published online: February 15, 2000

AIM: To study the cell types, localization, distribution density and morphology of APUD cells in the intestinal mucosa of stomachless teleost fishes.

METHOD: By using the peroxidase-antiperoxidase complex ( PAP ) immunocytochemical staining technique the identification, localization and morphology of immunoreactive (IR) endocrine cells seattered in the intestinal mucosa of grass carp (Cyenopharyngodon idellus), black carp (Mylopharyngodon piceu s) and common carp (Cyprinus carpio) were investigated with 20 kinds of an tisera prepared against mammalian peptide hormones of APUD cells, and likewise by using avidin-biotin-peroxidase complex (ABC) method those of silver carp (Hypophthalmichthys molitrix), bighead (Aristichthys nobilis), silver crucian carp (Carassius gibelio) and bluntnose black bream (Megalobrama amblyoce phala) were also studied with 5 different antisera. The replacement of the first antiserum by phosphate buffered saline (PBS) was employed as a control. IR endocrine cells were counted with a square-mesh ocular micrometer from 10 fields selected randomly in every section of each part of the intestine specimen. The average number of IR endocrine cells per mm2 was counted to quantify their dis tribution density.

RESULT: Gastrin (GAS), Gastric inhibitory peptide (GIP), glucagon (GLU), glucagon-like immunoreactants (GLI), bovine pancreatic polype ptide (BPP), leucine-enkephalin (ENK) and substance P (SP)-IR endocrine ce lls were found in the gut of grass carp, black carp and common carp, and somatos tatin (SOM)-IR endocrine cells were only seen in common carp. GAS, GIP and GLU-IR endocrine cells were found in the intestinal mucosa of silver carp, bigh ead, silver crucian carp and bluntnose black bream. Most of IR endocrine cells had the higher distribution density in the foregut and midgut, and were longer in shape. They had a long apical cytoplasmic process extended to the gut lumen and a basal process extended to adjacent cells or basement membrane and touched with it. Sometimes, the basal cytoplasmic process formed an enlarged synapse-like structure in the contiguous part with basement membrane. This phenomenon provide d new morphological evidence for neuroendocrine and paracrine secretory function of these enteroendocrine cells.

CONCLUTION: At least 8 kinds of IR endocrine cells were found in the gut of stomachless teleost species for the first time in China. These IR e ndocrine cells scattering in the gut mucosa belong to the APUD system. Among the m, the hormones secreted by SP-, ENK-, SOM- and GLU-IR endocrine cells belon g to the peptides of dual distribution in the brain and gut. This provided new evidence for the concept of brain-gut peptide. According to the cell types, dist ribution density, morphological characteristics and variety in shape of APUD cells in the gut of stomachless teleost fishes, it is deemed that the digestive tract of fishes is also an endocrine organ of great importance and complexity.

Keywords: stomachless teleost fishes, APUD cells, intestinal mucosa, immunocytochemistry