An electron microscopic study on the development of the trabecular meshwork and the inner wall of Schlemm' s canal of the albino rat.

Abstract

The development of the trabecular meshwork and Schlemm's canal of one hundred and four albino rat eyes (from the 14th day of gestation to the 30th day after birth) were observed with electron microscope. The results obtained are as follows:
1) The appearance of the anterior chamber angle can be observed on the 17th day of embryonic life with light microscope, while the immature trabecular meshwork is seen on the 15th day of embryonic life with electron microscope. Following the development of mesenchymal cells which fill the future anterior chamber angle, immature trabecular meshwork is formed and each trabecular sheets become flat as they develop and remaining mesenchymal cells are arranged to form future cornea and iris. Thus the chamber angle is formed. Atrophic change of the mesoderm was not observed during the period of the anterior chamber formation.
2) During the period between the 15th day of gestation and the 1st day after birth the endothelial cells which covers the trabecular fibers shows no change in morphology of the cytoplasm. However, the core of the trabecular fibers gradually achieves their mature morphology.
3) In some places, the trabecular fibers are not completely covered by endothelial cells.
4) The endothelial cells of the inner wall of Schlemm's canal have no basal lamina. Giant vacuoles was observed in the cytoplasms. In some specimens giant vacuoles show their openings toward the basal side of the cells and pores were formed on the surface of the endothelial cells. As the endothelial cells of the inner wall of Schlemm's canal achieves their mature morphology the thickness of the endothelial cells decrease and pinocytotic vesicles which appeared on the surface of the cells increase in number.