Forma, Vol. 7 (No. 2), pp. 167-181, 1992
Original Paper

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.