Amputated 



limb bud Two Months 



ositionoS Embryo 



definitive gland 



Milk line Epidermis 

 Limh bud 



Four Months Embryo 



'Human Embryo 



of six weeks showing anlage 



of the mammary glands. 



Duct-*- 



Seven Months Embryo 



Fig. 55. Development of Mammary Glands. The embryo (left) shows the 

 continuous milk line which degenerates in man, except in the pectoral 

 region. Other mammals develop a series of mammary glands on either 

 side. Super-numerary nipples appear in man as an anomaly. The cross 

 sections through the milk line show three stages in the development of the 

 glands and nipple. Compare with Fig. 54. (After Kollman, Tourneux 



and Basch.) 



B Marsupial 

 before lactation 



iP Seven months 

 Human Embryo 



C Marsupial 

 Lactating 



F Cow, showing 

 teat or pseudo- 

 nipple. 



Fig. 56. Diagrammatic drawings of Mammary Glands and Nipples. A 

 comparison of drawing D (Fig. 56) with the Seven Months Human 

 Embryo in Fig. 55 will explain the relationships of structures. (After 



Weber) . 



