Fig. 8. Involution is severely affected in the mutant mammary glands. (A) Hematoxylin and Eosin staining of mammary glands from wild-type mice (a,c,g) and mammary glands from MTA1-TG mice (b,d,h). Day 1 of involution (a,b), day 3 of involution (c,d), day 21 of involution (g,h). Carmine Red-stained whole mounts of mammary glands at day 21 of involution (e,f). Hyperplastic nodules are present in MTA1-TG mice. (B) TUNEL analysis of wild-type (a,c) and MTA1-TG (b,d) involuting mammary gland 1 day (a,b) and 3 days (c,d) of involution. (C) Quantification of tunnel-positive cells. Ten 200x magnification fields of view were randomly counted. The apoptosis index was calculated as follows: (number of TUNEL positive cells/total number of cells)x100. Statistical analysis was performed using Student's t-test. Error bars represent s.e.m. (D) Western blot analysis of Bcl-X_L expression in wild-type and MTA1 transgenic mice at days 1, 3 and 7 of involution (Inv). Vinculin was used as a loading control.