Development of mammary glands

  • Linear thickening of surface ectoderm (milk line) appears on ventral body
  • Extends from axilla to medial inguinal region
  • Line disappears except in pectoral region
development of mammary glands, milk line

  • 15 to 20 solid ectodermal buds arise in remaining milk line
  • Buds form solid cords
  • Which grow in underlying mesenchyme
  • Cord grows and branches in fetal life
  • Canalized before birth to form: Lactiferous sinus, Lactiferous duct, Secretory alveoli
  • Open in depressed area, which elevates after birth – to form the nipple
Image result for lactiferous sinus

At puberty:

  • Males: have ducts without alveoli
  • Females: Ovarian hormone increases branching of lactiferous duct, and increases fat between lobules. Therefore the mammary gland enlarges.

Congenital anomalies:

  1. Amastia – absence of one or two mammary glands
  2. Athelia – absence of one or two nipples
  3. Macromastia – large breasts
  4. Micromastia – small breasts
  5. Polythelia – accessory nipples
  6. Polymastia – accessory breast
  7. Gynaecomastia – male developing female breasts
  8. Klinefelter syndrome – XXY in males, therefore have enlarged breasts, wide hips and penis does not grow