Observation on the Basal Lamina of Duodenal Epithelial Cells during Metamorphosis of Xenopus laevis

Abstract

Summary: We studied the basal lamina of duodenal epithelial cells of Xenopus laevis during metamorphosis. During prometamorphosis (Stages 56-59) it was almost flat, except for areas where it curved along the many fingerlike processes present in the cellular base of epithelial cells. In the flat areas of basal lamina, a thin (50nm), low electron-dense layer of lamina lucida was identified. Next to it was a 50 nm layer of lamina densa with high electron density which curved along the cellular processes in what appeared as 2-3 layers. During the early stages of metamorphic climax (Stages 60-62), the curving of the basal lamina along the cellular processes was yet more extensive and layers of lamina densa, folded 2-4 times, predominated over single layers. In stage 61, the lamina densa further condensed by folding and the thickness of the basal epithelial cells was clearly visible; the condensed lamina densa beneath it gradually disappeared. During the later stages of metamorphic climax (Stages 63-66), the basal lamina became flat and the lamina densa exhibited only one layer. The thickness of the lamina densa was approximately 50 nm which was nearly the same as that of the primary epithelium during the early stages of prometamorphosis. The observed morphologic changes of the basal lamina during metamorphosis may be related to morphologic changes of the epithelium and underlying connective tissue, and the basal lamina may play an important role in these morphologic changes.

Observation on the Basal Lamina of Duodenal Mesothelial Cells During Metamorphosis of Xenopus laevis

“…The morphologic changes of the intestinal epithelium of Xenopus laevis during metamorphosis have been reported by Bonneville and Weinstock (1970), Hourdry and Dauca (1977) and McAvoy and Dixon (1977), and Kordylewski (1983) reported the changes in the thickness of the muscle layer and the morphologic changes of the smooth muscle cells. In addition to the aboves, Ishizuya-Oka and Shimozawa (1987a, b) reported the changes in the thickness of connective tissue situated between the epithelium and the muscle layer as well as the thickening of the basal lamina of epithelial cells in the small intestine during (Murata et al, 1988(Murata et al, , 1989. In case the morphologic changes of basal lamina are related to physical changes such as shortening of the digestive tract or narrowing of the lumen, the changes shall not only be observed in epithelial cells, and we now report the changes in the basal lamina of the mesothelial cells concurrently observed when the basal lamina of epithelial cells shows changes during metamorphosis.…”