Elongation and branching of mammary ducts during puberty is controlled by overarian steriod hormones. With the completion of puberty, an elaborate ductal network fully penetrates the mammary fat pad. Although alvolei proliferation and differentiation occurs mainly during pregnanacy, transcient differentiation can be observed during the estrus cycle (Robinson et al. Development 121, 2079-2090; 1995)
Inherently to organ development, significant differences can be observed in ductal and alveolar development during puberty. To illustrate variations in development, mammary tissue from seven mice (approximately 3 months of age) was analyized. One inguinal gland (#4) was biopsied during estrus, the other out diestrus. The top image is that of a gland estrus and the bottom panel shows the one at diestrus.
Contributed By
Laboratory of Genetics and Physiology
Section on Mammary Gland Biology
National Institutes of Health
Bethesda, MD 20892
Phone: 301-496-2726
Fax: 301-496-0839
e-mail: mammary@nih.gov
last update: July 1998