Mammary glands and feathers: Comparing two skin appendages which help define novel classes during vertebrate evolution

Randall B. Widelitz, Jacqueline M. Veltmaat, Julie Ann Mayer, John Foley, Cheng Ming Chuong

Research output: Contribution to journalReview article

30 Scopus citations


It may appear counter-intuitive to compare feathers and mammary glands. However, through this Evo-Devo analysis, we appreciate how species interact with the environment, requiring different ectodermal organs. Novel ectodermal organs help define evolutionary directions, leading to new organism classes as exemplified by feathers for Aves and mammary glands for Mammals. Here, we review their structure, function, morphogenesis and regenerative cycling. Interestingly, both organs undergo extensive branching for different reasons; feather branching is driven by mechanical advantage while mammary glands nourish young. Besides natural selection, both are regulated by sex hormones and acquired a secondary function for attracting mates, contributing to sexual selection.

Original languageEnglish (US)
Pages (from-to)255-266
Number of pages12
JournalSeminars in Cell and Developmental Biology
Issue number2
StatePublished - Apr 2007



  • Branching morphogenesis
  • Breast cancer
  • Development
  • Ectodermal organ
  • Evolutionary novelty

ASJC Scopus subject areas

  • Developmental Biology

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