Abstract
Morphological changes of developing duodenal villi in prenatal, postnatal and adult hamsters were examined in light and electron microscopy. Scanning electron microscopic observation revealed that the duodenal villi first appeared at 13.5 days of gestation as square-like protuberances. At birth, the shape of villi changed from square to columnar. After suckling period, the shape abruptly changed into flat leaf-like, and then completed the morphological differentiation into adult duodenal villi. On the other hand, growth and differentiation of surface structures such as large blebs at the apices of villi and creases on the lateral surface gradually proceeded with age. Light and transmission electron microscopic observation exhibited that at the time of first appearance of villi, the surface epithelium turned from stratified to single layered. Single-layered epithelial cells developed rapidly to accomplish their growth to a great degree about one day before birth. At birth, each of these absorptive epithelial cells had a structure almost similar to that in adult.
