Mouse Mammary Gland Development

The mammary gland develops mainly postnatally, when during pregnancy the epithelium grows out into the mammary fat pad and forms a network of epithelial ducts. During pregnancy, these ducts branch and bud to form alveoli. These alveoli produce the milk during lactation. After 7 days of lactation, involution was induced by force weaning the pups. The newly formed epithelium undergoes apoptosis and is removed from the tissue by neighbouring epithelial cells. Tissue remodelling leads to a morphology resembling a gland of a pre-pregnant mouse. Microarray analysis was used to measure mRNA expression of genes during puberty, pregnancy, lactation and involution in a Balb/c mouse strain. Keywords: developmental time course Total RNA was extracted from the 4th (inguinal) gland after removal of the lymph node. Individual samples represent RNA from one gland of one mouse. Samples were taken in triplicate (i.e. three mice per triplicate) for 18 time points of development.