Morphogenesis of the special circular muscle layer and of the interstitial cells of Cajal related to the plexus muscularis profundus of mouse intestinal muscle coat. An E.M. study.

The morphogenesis of the special layer and the interstitial cells of Cajal (ICC) related to the plexus muscularis profundus (PMP) of mouse intestinal muscle coat has been studied in foetuses at term, neonates not yet fed, suckling animals, weaning animals and adult animals. In foetuses at term, the special layer is absent, but presumed myoblasts of this layer are recognized in the tela submucosa facing the developing circular layer. The ICC, too, are not differentiated and presumed ICC-blasts are tentatively identified in submucosal cells related to nerve fibers. These nerve fibers are considered to belong to the developing PMP. In neonates, the special layer, ICC and PMP are recognizable, but are made up of poorly differentiated elements. In suckling animals, these three structures develop but become almost fully differentiated only at the end of the weaning period, whereas the other components of the muscular coat are already developed.