518 H. M. WAHL 



plexus surrounding this anlage. These vessels may be readily 

 followed in a new-born rabbit (fig. 2). At this period the 

 ducts spread out a short distance from the nipple anlage and 

 have narrow necks and dilated extremities. The chief superficial 

 blood vessels and their branches are distributed essentially as 

 in the adult. From the vascular trunks and their main branches 

 and from the chief branches to the superficial layer of the dermis 

 and to the cutaneous muscle lying near the gland anlage rami 

 may be followed to the nipple region and upwards in the con- 

 nective tissue surrounding the necks of the ducts into a plexus 

 lying immediately beneath the epidermis covering the anlage of 

 the nipple. As a rule, at this period the arterial and venous 

 rami take somewhat independent courses, although frequently 

 they parallel one another for a part of their course. The longer 

 ducts extend toward the main blood vessels and the rami coming 

 from these run parallel to the ducts. Frequently an arteriole 

 will run on one side of a duct, a venule on the other side. Capil- 

 lary plexuses surround the ducts, but are less well developed 

 about the necks of the ducts than about their expanded 

 extremities. 



Two months after birth the ducts have extended considerably 

 further from the nipple region and show many bulging pro- 

 jections, the anlages of branches (fig. 3). The vascular supply 

 of the gland is much elaborated. Special vessels to the nipple 

 region supply the capillary plexus about the necks of the ducts 

 and that part of the ducts lying near the nipple, while other 

 vessels from the cutaneous and muscular plexuses are beginning 

 to supply the extremities of the ducts. The nipple branches are 

 long slender tortuous vessels which give off few rami until near 

 the nipple. Some of them lie superficial to and others beneath 

 the free parts of the ducts. At the base of the nipple they turn 

 upwards toward the apex of the nipple which at this period is a 

 small bullet shaped projection. Usually one or more main rami 

 may be followed into the arterial rete about the mouth of the 

 ducts. Some of these rami lie at the periphery of the group of 

 ducts in the nipple, others in the midst of the group. Both sets 

 send branches to the capillary plexus about the necks and mouths 



