Analysis of epithelial outgrowth. Diamonds represent the average end to end length of total ductal outgrowth measured in arbitrary units in a transplanted gland at (a) 4 weeks and (b) 7 weeks for the null and wild-type or heterozygous (Wt/het) donor genotypes. The average numbers of branchpoints within a unit area are shown for (c) 4 weeks and (d) 7 weeks after transplantation. (e) Ductal outgrowths for 20 weeks after transplantation, mid-pregnancy, and 1 day postpartum (1D PP) are shown together. In all panels, solid lines connect the null with the Wt/het pair of contralateral transplants from the same recipient mouse. Dotted lines connect the mean of the outgrowths from contralateral glands in complete null-Wt/het pairs, and the mean lengths are listed at the termini of these lines. Asterisks represent the mean from all recipients of a given genotype, with mean lengths presented in italics in panels b and d.