Table 1.

Requirement of the PR in the stroma and/or the epithelium for alveolar development in mammary transplants analyzed post partum

Transplant	No. samples with alveolar growth/no. successful transplants
Mammary glands in toto
Stroma PR+/+/epithelium PR+/+	8/8
Stroma PR−/−/epithelium PR−/−	0/8
Fat pad injected with PR+/+ROSA26 epithelium cells
Stroma PR+/+/injected epithelium  PR+/+	6/6
Stroma PR+/−/injected epithelium  PR+/+	8/8
Stroma PR−/−/injected epithelium  PR+/+	6/6
Epithelium
Stroma (host) PR+/+/epithelial  transplant PR+/+	13/13
Stroma (host) PR+/+/epithelial  transplant PR−/−	0/13