Development of the Lens in Human Embryos: A Histochemical and Ultrastructural Study

Abstract

The early development of the lens was examined, using 36 externally normal human embryos at Carnegie stages 13–23 (4 to 8 weeks of gestation). Twenty-two embryos were sectioned serially and stained with periodic acid-Schiff and a modified method of PAS. In 14 embryos, not only the differential distribution of glycogen but also the ultrastructural change in the developing lens, with special reference to junctional complexes, were examined electron microscopically. At stage 15, when the lens vesicle was formed, glycogen was observed in the cytoplasm of the lens epithelium, especially in the posterior lens epithelium. From stages 16 to 18, when the posterior lens epithelium was differentiated into the primary lens fibers and elongated toward the anterior lens epithelium, the amount of glycogen increased in the basal cytoplasm of the primary lens fiber, where the intracellular organelles, such as the tubular vesicles, mitochondria and multivesicular bodies, began to aggregate. At stage 20, when the lens cavity was obliterated, glycogen was also present in the anterior lens epithelium. At stage 21, as the formation of the secondary lens fibers proceeded, glycogen was noted in the secondary lens fibers in the equator region. These findings suggest that the distribution of glycogen is associated with the formation of the primary and secondary lens fibers. In addition, we provide additional information that a lot of glycogen is distributed in the region where many intracellular organelles aggregate in the embryonic lens vesicles.

Immunohistochemical Study of 28-kD Heat Shock Protein in the Lens of Young Human Embryos

“…Ophthalmic Res 1996:28:270-274 vesicle in a stage-15 human embryo; however, aA-and aB-crystallin were observed over nearly the entire area of the lens vesicle [6], We previously reported that glycogen ap peared in the posterior portion of the lens ves icle at stage 15 [19], Therefore, the distribu tion of HSP28 in the lens vesicle at stage 15 was similar to that of glycogen rather than that of aB-crystallin. In the present study, HSP28 appeared in the anterior lens epithelium at stage 19.…”