Description
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.