Ultrastructural Study on the Development of Ciliary Body in Human Fetuses

ABSTRACT

Morphological development of the ciliary body was studied by electron microscope in human fetuses from 50 to 260 mm crown-rump length(11-30 weeks of gestational age). At a 50 mm(11 weeks) fetus, the anlage of ciliary body was not appeared. At a 70 mm(13 weeks) fetus, the anlage of ciliary epithelium was appeared as the folds were formed by invaginating vessels in the basal surface of pigmented epithelium at the rim of optic cup. At the time, the anlage of ciliary muscle was formed as the mesenchymal cells, which located between the rim of optic cup and the scleral condensation, different-iate into the myoblasts, and the unmyelinated nerve fibers and the axon terminals were found in the interstitial tissue of mesenchyme. At 100-260 mm(15-30 weeks) fetuses, the myoblasts of ciliary body continued to develop into typical smooth muscle cells. At 200-260 mm(20-30 weeks) fetuses, the well-developed infoldings in the basal lamina and the well-developed interdigitations in the lateral sur-face were observed at both pigmented and nonpigmented epithelia. At the time, ganglion cells, Schwan cells and axon terminals were observed in the interstitial tissue of ciliary muscle.