Quantitative study of the development of neurons and synapses in the visual cortex of rats reared in the dark during early postnatal life

Y. Fukui¹ and K. S. Bedi²

¹Department of Anatomy, School of Medicine, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770, Japan
²Department of Anatomy, University of Queensland, St. Lucia 4072, Brisbane, Queensland, Australia

(Received May 21, 1992; Accepted August 25, 1992)

Keywords: Rat, Dark-rearing, Neurons, Synapses, Visual system

Abstract. We investigated the effects on the synapse-to-neuron ratios in the visual cortex, of rearing male rats in the dark from birth until 30-days of age, followed in some cases by a 35-day period of rahabilitation in control lighting conditions. There were no significant differences in the numerical densities of neurons, synapses or synapse-to-neuron ratios between dark-reared and control rats at 30 or 65 days of age. These observations, together with previously published data, indicate the possibility that there may be a particularly vulnerable period of development for the rat visual cortex between about 30 and 40 days of age, when it is sensitive to light deprivation.