Morphological Characteristics of the Intestinal Mucosa in the Afghan Pika (Ochotona rufescens rufescens)

Abstract

The intestinal mucosa of the pika was examined with the naked eyes, a light microscope and a scanning electron microscope and was compared with that of the rabbit. The duodenal mucosa of the rabbit showed wavy folds different from so-called villi, while that of the pika exhibited leaf-like or columnar villi. In addition to the specific ileocecal lymphoid apparatuses, the pika had the peculiar region between the cecum and the proximal colon. That region called“the constricted portion”possessed characteristic net-arranged folds and welldeveloped muscular layers. At the lateral surface of these folds, small villuslike protrusions projected into the lumen in large numbers. The spiral fold ran around the mucosal surface of the rabbit cecum, whereas numerous slender protrusions, cecal digitations, projected into the lumen of the pika cecum. Although the colon of the pika showed a similar external figure to that of the rabbit, some differences were obviously found in histological structures. The first segment of the Pika proximal colon with three teniae possessed several protrusions and well-developed mucous glands, while that of the rabbit had neither protrusions nor mucous glands. The second segment of the Pika proximal colon with one tenia was covered with numerous villus-like protrusions, while that of the rabbit was composed of wart-like protrusions. The tubular mucous glands were observed in the lamina propria of the pika as well as the rabbit. The distal colon of the pika showed a flat mucosal surface and possessed tubular mucous glands as observed in the rabbit.