Normal and 6-aminonicotinamide impaired development of capillarization in occipital cortex of rat

During different embryonic and postnatal stages, 6-aminonicotinamide (6-AN) was administered to Wistar albino rats. The capillarization of the occipital cortex has been examined morphometrically. A 6-AN-vulnerable stage of prenatal development was found, which lasted to the 19th prenatal day and which only partly corresponds to the so-called 'critical stage' of capillary sprouting (Kapillarsprossung). Capillary sprouting was not impaired by 6-AN during postnatal stages. Impairment of capillarization by 6-AN might be the result of glial lesion. The importance of glia for capillarization is discussed.