. The breast: its anomalies, its diseases, and their treatment . x of Authors 703 Index of Subjects 715 THE BREAST CHAPTER ITHE NORMAL BREAST EVOLUTION Embryology.—At an early period in the development of certain mammals, (Sitzungsberichte der Gesellschaft zu Wiirzburg, 1892, p. 77)discovered that a slight ectodermal ridge could be seen, passing along each side of thebody from the axillae to the groins. To these he gave the name milch-leisten ormilk-lines, because they mark the general location of the future mammary milk-lines have now been observed in the e
. The breast: its anomalies, its diseases, and their treatment . x of Authors 703 Index of Subjects 715 THE BREAST CHAPTER ITHE NORMAL BREAST EVOLUTION Embryology.—At an early period in the development of certain mammals, (Sitzungsberichte der Gesellschaft zu Wiirzburg, 1892, p. 77)discovered that a slight ectodermal ridge could be seen, passing along each side of thebody from the axillae to the groins. To these he gave the name milch-leisten ormilk-lines, because they mark the general location of the future mammary milk-lines have now been observed in the embryos of pigs, guinea-pigs, rabbits,rats, cats, foxes, squirrels, moles, sheep, cattle, deer, bats, monkeys and other O. Schultze discovered for the lower mammals, Kallius and Brouha (AnatomischerAnzeiger, 1905) Schmidt, Schmitt, Strahl, Hirshland, Elze and others have shown to betrue for human embryos as well. On the latter they can first been seen in 9-mm. embryosand are quite distinct in 15-mm. embryos. When the embryos attain to a length of. Fig. I.—A series of pig embryos, showing the milk line in a, the interrupted line and appearance ofthe future nipples in b, and their further development in c, d and e. 26-60 mm. the lines cease to exist as such, but become broken up into a series of points,each forming a minute elevation through accumulation of the ectodermal cells. Theseconstitute the burgeons primordeaux or anlagen of future mammary number in the embryo bears no definite relation to the number of mammary glandsthat will finally appear in the adult animal, except that there can never be more mam-mary glands than there are primitive anlagen. Unless we except certain marsupialmammals (Didelphys) and insectivorous mammals, the number of burgeons primor-deaux is always in excess of the number of mammary glands normal to the species. Thus Schickele (Zeitschrift fiir Morph. u. Anthrop., Vol. I) found that the embryoguinea-pig exhibited 10 of t
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