Fig. 4.

Increased rate of α- and β-cell proliferation in islets of Gcgr^−/− mice during the perinatal period. Pregnant mice, pups, or adult mice were injected with BrdU, and the number of cells expressing the thymidine analog and a hormone was determined as indicated in Materials and Methods. The labeling index was determined as the number of GLU⁺ and IN⁺ cells containing the BrdU per total number of GLU⁺ or IN⁺ cells scored. Over 500 cells were scored per antibody/age/genotype (n = 3). Note the increased rate of α-cell proliferation in fetuses and young pups. In contrast, the rate of IN⁺ cell proliferation increased only after birth. In adults, the rate of IN⁺ and GLU⁺ cell replication in both strains was very low (data not shown). *, Less than 0.05; **, less than 0.01.