Effect of IGF-I gene therapy on lactotropic cell size. Lactotroph cell surface (CS) in the pituitaries of animals submitted to no treatment (intact), control treatments (E2 only and E2 + RAdGFP) or IGF-I gene therapy (E2 + RAd-IGF-I). Columns represent mean values whereas bars over columns represent SEM values. Five pituitaries per group were assessed. Asterisks indicate a highly significant difference from the intact group.