701 Int. J. Morphol., 26(3):701-705, 2008. Microarchitectural Adaptations in the Stomach of African Tree Pangolin (Manis tricuspis) Adaptaciones Microarquitecturales en el Estómago del Pangolin Africano (Manis tricuspis) Ofusori, D. A.; Caxton-Martins, E. A.; Keji, S. T.; Oluwayinka, P. O.; Abayomi, T. A. & Ajayi, S. A. OFUSORI, D. A.; CAXTON-MARTINS, E. A.; KEJI, S. T.; OLUWAYINKA, P. O.; ABAYOMI, T. A. & AJAYI, S. A. Microarchitectural adaptations in the stomach of african tree pangolin (Manis tricuspis). Int. J. Morphol., 26(3):701-705, 2008. SUMMARY: The microarchitecture of the pangolin’s stomach favouring the high chitinous diet has been less waived into, despite extensive morphological investigations. Histological analysis of the microanatomy will provide powerful tools for interpretation to yield reliable insights. We investigated this by fixing the tissues in 10% formol saline for histological analysis. Serial sections at 5 μm thickness were subjected to general staining methods for light microscopic study (Haematoxylin and eosin, Van Gieson’s and Verhoeff’s). The results revealed basic structural arrangements in their coats, with a modification of the epithelial lining of cardia and fundus into stratified squamous keratinized epithelium. These modifications were also reflected in the distribution of collagen and elastic fibers in the various layers (coats) of the stomach. The present study has shown that there was an adaptation of the stomach of African tree pangolin to its diet as reflected in the microarchitectural configuration. KEY WORDS: Stomach; Microarchitecture; Histological analysis; Diet; Coats. INTRODUCTION The African tree pangolin (M. trisuspis), a mammal, is commonly found in the western part of Nigeria and consumes a very specific insectivorous diet (Griffiths, 1990; Ofusori et al., 2007). Fossil pangolins are first found in the Eocene in Europe. In the Messel shales of Germany they are particularly well preserved, showing that their characteristic scales were already developed. Recent DNA analysis has shown them to be bizarre offshoots of the Carnivora - the carnivores such as cats, dogs, bears, hyenas, civets and mongooses (Schlitter, 2005). Pangolin is an animal with short legs covered in brownish red overlapping scales making it look like a pinecone (Fig. 1.). It has a long, slightly-flattened prehensile tail (equally scaled), and 5 long curved claws on each foot. Its head is small and pointed with very small eyes protected by thickened eyelids, and it has a long sticky tongue for catching ants and termites. This rod- shaped tongue is covered with sticky saliva which is used as a tool to collect prey by inserting it into the termite tunnels (Pangolin Specialist Group, 1996). They have no teeth and their gizzard-like stomach may be specially adapted for grinding food. Ofusori et al. revealed from their work on the morphometric study of the stomach of M. tricuspis that the corpus is more metabolically active than the other parts of the stomach. It is therefore expedient to study the microarchitectural adaptations adopted by pangolin’s stomach to cope with their diets. The general sections of the mammalian gut (including the stomach under investigation) are usually specialized to suit the dietary requirement of particular species (Hildebrand & Goslow, 2001; Schlitter). Pangolin will often choose the larger member of the ant and termite population (for example they will choose against the smaller workers); this decreased the percentages of chitin. Calculating the nutritional value of arthropods is difficult, due to the presence of their hard exoskeleton that serves to protect their bodies. The exoskeleton and the chitin components provide a relatively indigestible substance (Griffiths et al.). In addition to the difficulties of digesting the chitin, the latter surrounds and protects the softer nutrients which are rich in fat and protein (Redford, 1983). The sand and ditrus is known to add bulk to the digestive load of insectivores and reduce the caloric proportions of their digestive content (Cohan, 1984). This finding is consistent with other ant and termite eaters (Redford, 1983). Department of Anatomy, and Cell Biology, Faculty of Basic Medical Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria