Vascularization in the primate visual cortex during development

We studied the relationship between vascularization and neuronal activity in the visual cortex during postnatal development in the primate. Analyses were focused on layer IVC that displays a sequential pattern of maturation for the magno- and parvocellular systems in separate sublayers, respectively IVCalpha and IVCbeta. Cytochrome oxidase and endogeneous alkaline phosphatase histochemistry was used to analyse, on the same sections, the laminar patterns of cortical activity and vessel density in the primary visual cortex of the marmoset (Callithrix jacchus). Experiments were carried out in five young and two adult animals. We showed that the temporal pattern of angiogenesis differs in layer IVCalpha and IVCbeta. During the first postnatal month, vessel density is higher in IVCalpha than in IVCbeta and runs parallel to cytochrome oxidase intensity. In 2-month-old animals, both vessel densities and cytochrome oxidase activity are similar in IVCalpha and IVCbeta. In adults, the vessel densities in IVCalpha and IVCbeta are the reverse of those observed during the first postnatal month. Vessel diameter does not account for this evolution in vascular patterns. In the discussion, we suggest that such a developmental time-course of angiogenesis might be linked to the synaptogenesis requirements that proceed differently for the magno- and parvocellular systems in the primate striate cortex.