Calf and bovine lenses of 0.98 and 8.40 years old were separated mechanically into lens equator and inner cylinder. The inner cylinder was cut into 10 to 11 sections by a microsectioning device. These sections were investigated on the protein profiles of water-soluble crystallins, stained for proteins by Coomassie Blue (CB). These crystallins were also specifically stained purple for free sulfhydryl groups (SH). It appeared that all crystallins that were stained blue for proteins were also stained purple for sulfhydryl groups. This means that all crystallins contain free sulfhydryl groups. Going from anterior and posterior cortex to the nucleus of the lens, there was an appreciable increase of the percent of gamma-crystallins, whereas especially in the older lenses a decrease of gamma-crystallins could be observed in the lens equator and the anterior and posterior cortices. A stainability factor F = %SH/%CB was calculated for all crystallins. HM-, alpha- and beta s-crystallins exhibit high values of factor F. For the bovine lens, factor F of HM-crystallin displayed a maximum in the nucleus, whereas this factor decreased for gamma-crystallins towards the nucleus. This microsectioning technique allows for determining age-related differences between the sections obtained. This may lead to a comprehensive understanding of age-related changes within one lens, including cataractous changes.