DEVELOPMENT OF THE BLOOD VESSELS OF THE 

 MAMMARY GLAND IN THE RABBIT 



H. M. WAHL 



From the Anatomical Department, University of Wisconsin 



SIX FIGURES 



The mammary glands receive their blood supply from the 

 superficial blood vessels of the thoraco-abdominal walls. The 

 chief arteries distributing blood to these superficial vessels in the 

 rabbit are the thoraco-epigastric (external mammary), arising 

 from the subclavian, and the superficial epigastric arising from 

 the femoral. The internal mammary furnishes several small 

 branches which pass between the ribs to the skin and a large 

 epigastric branch. A small branch from the hypogastric artery 

 passes to the region of the inguinal gland. There is a fairly 

 constant branch from the lateral thoracic to the thoraco-epigas- 

 tric. The intercostals furnish little of the blood supply. From 

 the main arterial trunks branches are freely distributed. Anas- 

 tomoses are frequent between the branches. 



The larger veins as a rule parallel the arteries. The thoraco- 

 epigastric vein is an exception in that it enters the axillary 

 rather than the subclavian vein. The smaller veins and arteries 

 are less apt than the main trunks to parallel one another. The 

 terminal branches interdigitate in such a way as to insure an 

 even distribution of blood in the capillaries. 



The main branches lie in the subcutis superficial to the cutane- 

 ous muscle. From these vessels rami pass, on the one hand, 

 toward the skin, on the other, out over the surface of the muscu- 

 lature, on which an extensive rectangular plexus is formed. From 

 both sets of branches, as well as from the main vessels, rami pass 

 into the mammary glands. 



During embryonic development the cutaneous vessels are 

 formed from the capillary plexus which is developed on the 



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