A comparative histochemical study of the distribution of mucins in the gastrointestinal tracts of three insectivorous mammals

Abstract

a b s t r a c tThe distribution of mucous secreting goblet cells was examined in the gastrointestinal tracts of three insectivores namely: Acomys spinosissimus (Southern African spiny mouse), Crocidura cyanea (Reddish gray musk shrew) and Amblysomus hottentotus (Hottentot golden mole) in order to improve our understanding of the quality and composition of the protective intestinal biofilm. Intestinal tracts were fixed and processed to wax for histology. Serial transverse sections were stained using alcian blue-periodic acid Schiff, alcian blue-aldehyde fuchsin and alcian blue-high iron diamine techniques. Photomicrographs of the stained sections were analyzed by quantifying the number of goblet cells containing mucins per mm 2 in the surface epithelial or crypt areas. Neutral mucins predominated in the gastric epithelium of all three insectivores, while sialomucins were absent in the stomach of C. cyanea. In all three species, goblet cells producing a mixture of neutral and acid mucins were most abundant throughout the intestinal tract as were cells secreting a mixture of sulfomucins and sialomucins. However, differences between the insectivore species were observed in the qualitative expression and distribution of mucins throughout the intestinal tract. Similarities between the insectivores of this study and other distantly related species suggest that mixed mucin goblet cells are essential for the formation of the biofilm, irrespective of their diet or taxonomy.

The distribution of mucous secreting cells in the gastrointestinal tracts of three small rodents from Saudi Arabia: Acomys dimidiatus , Meriones rex and Meriones libycus

“…This was true in M. rex in the present study where the number of sulfomucin secreting goblet cells increased significantly towards the distal GIT. In accordance, Boonzaier et al (2013) observed significantly higher numbers of sulfomucin secreting cells in the large intestine than the duodenum in C. cyanea and A. spinosissimus.…”

“…The small intestine of A. spinosissimus, Crocidura cyanea (Boonzaier et al, 2013) and humans (Subbuswamy, 1971) contains predominantly neutral mucin secreting goblet cells, but this was not the case in the species in the current study, as mixed mucin secreting cells was the predominant type in the small intestine. A trend of exclusively acid mucins secreting cells increasing steadily from the duodenum to the distal colon was noted in A. spinosissimus ( Boonzaier, 2012) and M. rex (present study).…”

“…Although the present study did not determine the thickness of the mucous layer a significant increase in the total number of goblet cells per total area was observed in all three species for both staining methods. Similarly, an increase in numbers of mucus secreting goblet cells is present in the colon of the human (Forstner, 1978) and three insectivorous mammalian species (Boonzaier et al, 2013). Due to the vulnerability of sialomucins to bacterial degradation, sulfomucin secreting cells are expected to dominate in the large intestine where the bacterial load is high (Fontaine et al, 1996, Deplancke and Gaskins, 2001, Hino et al, 2012and Machado-Neto et al, 2013.…”

“…Sample collection from the GIT, histochemical procedures, measurements, quantification of the mucin cell types and statistical analyses, are based on the procedures as described in Boonzaier et al (2013). Briefly, tissue samples taken from the glandular region of the stomach, the proximal area of the duodenum (in order to visualize Brunner's glands), the jejunum, the ileum, the caecum and the proximal and distal colon were subjected to routine histological processing through to wax.…”

“…On the other hand, A. dimidiatus is mainly a granivore but also consumes small numbers of invertebrates (Varty, 1990). Over the years, several studies mapped the distribution of intestinal mucin-secreting cells in various mammalian (Sheahan and Jervis, 1976;Filipe, 1979;Coetzee et al, 1995;Kotzè and Coetzee, 1994;Boonzaier et al, 2013) and fish species (Tibbetts, 1997;Cao and Wang, 2009). Despite this, mucin distribution in normal tissue is still an area which needs further investigation (Hattrup and Gendler, 2008).…”