Effects of zinc deficiency on morphogenesis of the fetal rat eye

Maternal zinc deficiency during pregnancy results in a high frequency of fetal eye malformations in the Long-Evans rat. In this study we examine the development of the eye from days 12 through 21 of gestation in conceptuses of dams fed deficient or adequate levels of zinc and also examine maternal plasma and conceptus zinc concentrations during this period. Dams were fed diets containing 0.5 (0.5 Zn group), 4.5 (4.5 Zn group), or 100 (100 Zn AL group) micrograms zinc per gram diet ad libitum, or 100 micrograms zinc g-1 diet in amounts restricted on a daily basis to the intake of matched animals from the 0.5 Zn group (100 Zn RI group). Conceptuses were removed and maternal plasma was collected on days 12, 14, 16, 19 and 21 of gestation. Maternal plasma and conceptus zinc concentrations reflected maternal dietary zinc level, with dam plasma Zn concentrations in the order of 0.5 Zn group less than 4.5 Zn group less than 100 Zn group on all days. A similar pattern held for embryo/fetus zinc, except for days 19 and 21, at which times the 0.5 Zn and 4.5 Zn fetuses had similar zinc concentrations. Histological examination of the developing eye of 0.5 Zn fetuses on days 12 and 14 revealed that invagination of the optic cup was often deficient, and that closure of the choroid fissure did not occur, resulting in colobomata and retinal folding visible at term. A very few fetuses were found at term to be anophthalmic or have only remnants of ocular tissue.(ABSTRACT TRUNCATED AT 250 WORDS)