An immunohistochemical study of endocrine cells in the proximal duodenum of eight marsupial species*
CHIE TAKAGI, JUNZO YAMADA, WILLIAM J. KRAUSEt,
NOBUO KITAMURA AND TADAYUKI YAMASHITA
Department of Veterinary Anatomy, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080, Japan
t Department of Anatomy, School of Medicine, University of Missouri-Columbia, Columbia, Missouri, USA
Although numerous reports have described endocrine cells in the gastrointestinal mucosa of eutherian mammals, only a few studies have been published on those of metatherians (Krause, Yamada & Cutts, 1985, 1986, 1989; Barbosa, Nogueira, Penna & Polak, 1987 ; Yamada, Krause, Kitamura & Yamashita, 1987). Since marsupials are considered to be an example of a convergence evolution, it was of interest to compare gut endocrine cells of eutherians (placentals) and metatherians (marsupials) having similar dietary habits.
It is well established that there are several types and large numbers of endocrine cells in the duodenum. The proximal duodenum is also characterised by the presence of duodenal glands (Brunner's glands) (Carleton, 1935 ; Krause, 1972). Brunner's glands are peculiar to mammals including marsupials but their distribution in the duodenum and the nature of their secretory product vary according to species (Krause, 1987).
In the present study, the proximal duodenum from eight marsupial species with differing dietary habits was examined immunohistochemically to determine the types and frequencies of endocrine cells present. These observations are compared to those reported in eutherian species that have similar diets.