The distribution and frequency of occurrence of endocrine cells in the gastrointestinal tract of the Philippine carabao (Bubalus bubalis) were studied by immunohistochemistry. Fourteen types of immunoreactive (IR) endocrine cells were revealed. Among the cell types, only chromogranin, serotonin, and bovine pancreatic polypeptide (BPP) were present in the entire gut, while the others showed restricted distribution: somatostatin, gastrin, and cholecystokinin in the abomasum and small intestine; methionine-enkephalin-Arg6-Gly7-Leu8, motilin, neurotensin, secretin, gastric inhibitory peptide, and substance P in the small intestine; peptide tyrosine tyrosine (PYY) in the large intestine; and glucagon in the whole intestinal tract. Most of the cell types showed peak density in the pyloric, duodenal, or rectal region. The highest cell type heterogeneity was observed in the duodenum. The distribution profile of the gut endocrine cells in the carabao is closely related to that in the Holstein cattle. Important findings include the occurrence of BPP-IR cells in the entire gut and the high frequency of PYY-IR cells in the large intestine.

The cecal surface epithelium of cattle was lined entirely by columnar cells except near the openings of the glands where a few partially depleted goblet cells were encountered. Surface columnar cells with pale cytoplasm, indented (sometimes dome-shaped) apical border and irregular microvilli, were also found near the gland orifices. Surface columnar cells near the openings of the glands contained large cytoplasmic vacuoles and lysosomal-like bodies. Near the extrusion zone, however, the columnar cells contained highly indented and apically displaced nuclei. The glands were usually long and straight and lined by an epithelium concisting mainly of undifferentiated and goblet cells. There were few entero-endocrine and non-epithelial cells (intra-epithelial lymphocytes and globule leukocytes). Paneth cells were absent.The undifferentiated cells contained many free ribosomes and apical secretory granules. Some of these cells were undergoing mitotic division. Goblet cells exhibited a typical brandy-glass appearance and showed dark and light mucigenous granules. Endocrine cells with polymorphic secretory granules and cells with more uniform secretory granules were identified in the basal part of the epithelium. Globule leukocytes and intra-epithelial lymphocytes were usually encountered near the basal part of the epithelium.The lamina propria was highly cellular. It contained many plasma cells, mast cells and small lymphocytes, and few eosinophils, neutrophils and globule leukocytes. Some of the plasma cells contained large, dense Russell bodies within the cisternae of the rough-surfaced endoplasmic reticulum. The neutrophils displayed distinct populations of small and large cytoplasmic granules. Some of the eosinophilic granules showed narrow crystalline cores. Large lymphocytes were found in the lamina propria, but occurred less frequently than small lymphocytes.literature. Using the scanning electron microsope, WILLE (1975) examined the surface of the cecal mucosa in cattle, goat and sheep. He observed that the openings of the cecal intestinal glands in cattle were located in flat, round or oval-shaped surface elevations. In contrast, the openings of the cecal intestinal glands in the goat were wider and irregularly shaped. The surface morphology of the cecal mucosa in the sheep was similar to that of cattle. Modern veterinary histology texts by SAJONSKI/SMOLLICH (1972), BANKS (1981), and DELLMANN/BROWN (1981) do not contain a description of the ultrastructural features of the bovine cecal mucosa. U.S. Copyright Clearance Center Code Statement: 034&2096/85/1402-0116$02.50/0 Ultrastructural Features of the Bovine Cecal Mucosa 117Electron microscopic studies of the cecal mucosa in other species are scarce. The work by KANAKOUDIS (1973) in the horse dealt mainly with the secretory, granule-containing surface columnar cells. The fine structure of surface columnar cells overlying lymphoid nodules in the dog was described by ATKIN~SCHOFIELD (1972). The ultrastructure of the cecal mucosa has been ivnestigated in the rabbit ...