Morphological and Histochemical Features of the Duodenal Glands in Six Marsupial Species: The kangaroo, native cat, marsupial mouse, bandicoot, koala, and wombat (William J. Krause) Colleen Baumunk Histology /04/03

Purpose of the Investigation: Comparison of Brunner’s glands of selected Australian species from five families with those of the opossum (Didelphis virginiana) Wombat Native Cat Bandicoot

Background: Duodenal glands of 6 marsupial species were studied and their glands examined and compared between species and to the opossum Comparative studies have shown that a majority of the species show the glands beginning at the gastrointestinal junction and extending variable distances along the intestinal tract Duodenal glands lie mainly in the submucosa and empty into crypts of Lieberkuhn

Background Continued: Brunner’s glands The mucus secretions from the Brunner's glands pass through the muscularis mucosa via ducts on their way to the lumen. Submucosa Muscularis Mucosa Muscularis Externa

Background Continued: Goblet cell Lining epithelium of columnar cells with microvilli; the goblet cell is pouring out mucus.

Background Continued: Goblet cells and Brunner’s glands Goblet cells and Brunner’s glands under the muscularis mucosa (in the submucosa) are found only in the duodenum Brunner’s Goblet cells Submucosa Muscularis Mucosa Lamina Propria

Background Continued: Crypts of Lieberkuhn Crypts of Lieberkuhn found in lamina propria

Histochemistry Definitions: Alcian blue: dye used to demonstrate sulfated polysaccharides & to detect glycoproteins; used in combination with PAS Acid mucopolysaccharides – stain blue Nuclei – stain red Periodic acid-Schiff stain (PAS): a tissue staining procedure; strong staining occurs with polysaccharides & mucopolysaccharides PAS positive - stain red-violet

Materials and Methods: Blocks of tissue including the gastrointestinal tract (GI- tract) were removed from both sexes of each of the species Species studied included: 11 great grey kangaroos 3 short-nosed bandicoots 10 brown marsupial mice 2 eastern native cats 5 koalas 2 wombats

Materials and Methods Continued: For macroscopic study, specimens were prepared (by the Landboe-Christensen Method) for staining of the duodenal glands For light microscopy, tissues were fixed in Bouin’s solution, and stained with hematoxylin and eosin, Mallory’s trichome, and van Gieson. Histochemical methods were fixed in buffered 10% neutral formalin

Results: Macroscopic & Light Microscopy Duodenal glands of the kangaroo, bandicoot, marsupial mouse and native cat form a narrow glandular collar immediately distal to the pyloric sphincter & exhibit lobulation Kangaroo Brunner’s Glands: 25mm distal to pyloric sphincter to gastric mucosa Secretory Tubules: large pyramidal cells (sero-mucous)

Results: Macroscopic & Light Microscopy Bandicoot Brunner’s Glands: limited area (5.5mm) Lobes aren’t as complex as the kangaroo Duct system empties onto intestinal epithelium, independent of the crypts of Lieberkuhn Cells are more mucous in appearance compared to the kangaroo

Results: Macroscopic & Light Microscopy Marsupial Mouse and Native Cat Brunner’s Glands: 5mm and 8mm distal to pyloric sphincter Lobes aren’t as complex as the kangaroo Duct systems closely resemble that of the bandicoot Glands of the mouse:  Serous in appearance, oval nuclei, dense granules & a basophilic cytoplasm (stains readily with basic stains) Glands of the native cat  Mucous in nature, crescent-shaped nuclei & a clear cytoplasm

Results: Macroscopic & Light Microscopy Koala and Wombat Brunner’s Glands: 80mm and 180mm distal to pyloric sphincter Glands aren’t as complex nor are they restricted to a narrow glandular collar like the previous species Glands empty into intestinal lumen Secretory tubules of Koala and Wombat: Cells are intermediate between those of the mouse and the native cat (serous and mucous) Epithelium of the ducts: similar in appearance to the secretory epithelium comprising the glands

Results: Histochemistry Goblet cells: All species showed alcinophilia at pH 2.5 Alcian Blue and PAS Heterogeneous population of Goblet cells: Kangaroo, wombat, & marsupial mouse Duodenal Glands: Failure to stain with alcian blue at pH 1.0 or 2.5: kangaroo, native cat, marsupial mouse, and bandicoot Successful staining with alcian blue at pH 2.5: koala and wombat

Results: Electron Microscopy Ultra structural observations confirm the light microscopic observations Duodenal glands of all species: Large pyramidal cells that rest on a basal lamina Basal cell surface smooth, without any specialization Cells show a definite polarity:  Oval shaped nucleus located at the base and apically-placed granules Species differences do exist with regard to the morphology of granules & the relative proportions of cell organelles

Discussion: Duodenal glands of kangaroo, bandicoot, marsupial mouse, and native cat are similar to the opossum Glands are restricted to the submucosa of the proximal duodenum & form a narrow glandular collar immediately distal to the pyloric sphincter However, differences are seen between species Duodenal glands of the koala and wombat have little similarities to the opossum The koala and wombat’s glands aren’t restricted and do not form a glandular collar

My Interpretation: The histological techniques employed in this article enhanced the comparison between the species and the correlation with the opossum I don’t think I would have done anything different with this article; although the author stated that it’s hard to establish a meaningful relationship between the distribution of Brunner’s glands of various species

References: Krause, J. W., Morphological and Histochemical Features of the Duodenal Glands in Six Marsupial Species, Journal of Morphology, vol. 140, pg ames/h_fram17.html /histoweb/gitract/gitract.html