Fig. 1.

Development of the mammary gland. (A) Ventral view of an embryo at 28-days gestation showing mammary crests. (B) Similar view at 6-week gestation showing the remains of the mammary crests. (C) Transverse section of a mammary crest at the site of the developing mammary gland. (D–F) Similar sections showing successive stages of breast development between the 12^th week of gestation and birth. (Reprinted with permission from Moore KL, Persaud TVN, Torchia MG, The Developing Human: Clinically Oriented Embryology. 9^th ed. 2013 Copyright Elsevier).