Author: Nat Pernick, M.D. (see Authors page)
Revised: 24 September 2012, last major update March 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.
● Breast is considered an epidermal gland because it develops as diverticula of epidermis into dermis
● Breast is also considered a modified and highly specialized apocrine gland
● Mammary gland development begins at week 4, when ectoderm and underlying mesoderm proliferate and differentiate into skin
Week 4: paired ectodermal thickenings called mammary ridges or milk lines develop along ventral embryo and extend in curvilinear convex pattern from axilla to medial thigh; ridges will eventually disappear except at 4th intercostal space on anterior thorax, where mammary gland develops
Week 5: remnant of mammary ridge ectoderm proliferates and is termed primary mammary bud
Week 7: primary mammary bud grows downward into underlying dermis
Week 10: primary mammary bud branches into secondary buds
Week 12: secondary mammary buds start lobule development
Week 20: small lumina develop within mammary buds that coalesce and elongate to form lactiferous ducts
Month 5: areola is formed by ectoderm
Micro description (Histopathology)
Lifetime mammary gland development
Electron microscopy descriptions
Electron microscopy images
End of Breast-nonmalignant > General > Embryology
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