Neurogenetic gradients in the hamster visual pathway

Abstract

The dorsal lateral geniculate nucleus, suprachiasmatic nucleus and superior colliculus of the hamster were examined autoradiographically after administration of [ 3H]thymidine for the presence of spatiotemporal gradients of neuron production and for the relationship between neuron cell body size and birthdate. The dorsal lateral geniculate nucleus had a dorsolateral-to-ventromedial (superficial-to-deep) gradient of neuron production, the suprachiasmatic nucleus had a caudoventral to rostrodorsal gradient, and the superior colliculus had a complex laminar gradient. In the lateral geniculate nucleus and in the superior colliculus, labeled neurons were typically larger than unlabeled neurons at early stages and unlabeled neurons were typically larger than labeled neurons at late stages, however, variation in neuron size does not account for the neurogenetic gradients in hamsters.