The development of the eye: Study of serial sections of 4, 6, 12 mm rat embryos, 10 mm pig embryo and 36 somites chick embryo.

ABSTRACT

Serial sections of rat embryos measuring 4, 8, 12 mm were carefully studied in relation to the serial sections of 36 somites chick and 10 mm pig embryos under light microscope to compare eye development. The eyes of the 4 mm rat embryo were at a younger stage than those of the 36 somites chick embryos, but at about the same stage as the 10 mm pig embryo. At this stage, the optic cup has already been formed but the lens has incompletely undergone double fusion. The eyes of the 6 mm rat embryo can be compared with those 36 somites chick embryo, as the optic is divided into outer pigmented and inner nervous layers, and the lens is characterized by a thinner anterior lens epithelium and thicker posterior lens fibre. Nearly fully developed eyes, with the surrounding structures, are also shown in this study by the higher magnification of the eye of the 12 mm rat embryo. If rat embryos are to be used as study models for studying the development of the eye, 4-6 mm rat embryos are at the most suitable stages.