postnatal development of the visual cortex of albino rat and inorganic lead

ABSTRACT

Albino rats were used in the present study. Two groups of pregnant female animals, one served as control and other as experimental. The experimental mothers were fed with chow, tap water and libitum and 1% lead carbonate, from the first day of parturition. The pups from both groups were taken at the postnatal ages of 3, 9, 12, 15 and 21 days from both groups. Brains were extracted and fixed in 10% neutral formalin. The primary visual cortex was located according to Krieg [1946] map. It was processed for histological technique. Sagittal sections were cut at 10 u thick and stained with Einarsons gallocyanine. This study showed that the development of rat visual cortex is competed about day 21, when the neurons achieve their mature appearance as indicated by the increased size of cell body and nuclei; differentiation of the cells; the nuclei became vesicular with prominent nucleoli and increase Nissl's granules and there was also an increase in thickness of the cortex and a decreased packing of the neurons. The offsprings of rats fed on the inorganic lead starting from day 89, had an extensive changes compared to age matched control. Stratification of the visual cortex comes less distinct all over the ages used. Maturation of layer V and layer II/III is delayed. There is also cavitation, and neurocytic chromatolysis which is pronounced at day 12 and is clearly distinct at day 15. Pericapillary and capillary dilatation are noticed