Developmental Changes in the Cecal Mucosa of the Afghan Pika (Ochotona rufescens rufescens): A Comparison with the Rabbit

Abstract

Morphological changes in the pika cecal mucosa from the late fetal stage to the adult stage were observed mainly by scanning electron microscopy and were compared with those of the rabbit. The cecal mucosa of both the rabbit and the pika could always be divided into two portions, that is, a protruded region and a basal region.
The basal region of the pika cecum showed a similar morphological change to that of the rabbit cecum in that the basal regions of both the pika and the rabbit were covered with columnar or round villi from the late fetal stage to 5 days after birth. After 10 days, villi disappeared and as a result their basal regions exhibited irregular short ridges.
By contrast, the protruded region of the pika cecum showed a different developmental process from that of the rabbit cecum. The protruded region of the rabbit showed a fold at 25 days of gestation and developed progressively in accordance with age to form the spiral fold. In the pika cecum, the protruded region also revealed a fold at the late fetal stage, but the fold divided into many hump-like protrusions after birth and formed cecal digitations at 5 days after birth. After 5 days, the cecal digitations were gradually transformed from a short columnar to a long columnar shape and finally to a flat slender form at the adult stage.