DEVELOPMENT OF THE REPRODUCTIVE ORGANS. 2037 



the gland and radiate in the paramammary fatty tissue (Williams) emphasizes the 

 need for incisions that shall permit the removal of all such portions of possibly dis- 

 eased glandular tissue. 



(r) The usual defect in the retroglandular fatty envelope, bringing the glandu- 

 lar lobules into intimate relation with the pectoral fascia and muscle (Heidenhain), 

 facilitates extension of the disease in that direction and indicates the free removal of 

 the pectoralis major in most cases. 



{d ) The lymphatic distribution {vide supra) supplies the same indication as to 

 removal of the greater pectoral and — to a lesser degree — as to the lesser pectoral also. 

 It, of course, points unmistakably to the need for thorough cleaning out of the axilla. 

 In doing this it is well to remove the chain of lymphatic nodes— pectoral, central, 

 deep, subscapular, etc. — in one piece, not only because it minimizes the risk of 

 infection of healthy structures during the operation (Cheyne), but because if the 

 clavi-pectoral fascia (suspensory ligament of the axilla) and the axillary fascia, 

 together with the greater part of the pectoralis minor muscle (on account of the 

 continuity of its sheath with the clavi-pectoral fascia), are removed in one piece, the 

 groups of nodes enumerated above and embedded in them will be removed also 

 (Leaf). To this there are three exceptions: ( i ) a node of the subscapular group 

 sometimes projects backward and is found between the teres minor and infraspinatus 

 muscles ; (2) some nodes of the infraclavicular group may lie to the outer side of 

 the axillary vein, and when this is so, as the suspensory ligament is stripped off the 

 inner side these glands would remain behind ; (3) the cephalic node would not be 

 reached during the removal in one piece of the ligament and axillary fascia with their 

 contained groups of nodes. Of course all these nodes should be sought for and 

 removed separately (Leaf). 



(e) The most important blood-vessel in danger during the operation is the 

 axillary vein (page 888), made somewhat more prominent — together with the artery 

 and the brachial plexus — when the arm is raised and the head of the humerus is made 

 to project into the axilla. These structures normally lie on the outer wall of the 

 axilla, but may be so embedded in a mass of cancerous tissue as to be difficult of 

 recognition. On the posterior aspect of the axilla the subscapular vessels and (in 

 close proximity to the subscapular nodes) the long subscapular nerve supplying the 

 latissimus dorsi muscle should be avoided. The inner (thoracic) wall of the axilla 

 is the region in which the dissection may be conducted with the greatest freedom, 

 the posterior thoracic nerve running almost vertically downward in close contact with 

 the outer surface of the serratus magnus muscle to which it is distributed. The 

 arteries met with or divided in the course of the operation are ( i ) the pectoral 

 branches of the acromial thoracic ; (2) the alar thoracic ; (3) the long thoracic 

 (external mammary) running along the lower border of the pectoralis minor muscle ; 

 (4) lateral branches from the second, third, and fourth intercostal arteries ; and (5) 

 anterior perforating branches of the internal mammary artery, emerging at the second, 

 third, and fourth intercostal spaces. The vessels in the last two groups are normally 

 small, but by enlarging during the growth of a carcinoma and by retracting after 

 division to beneath the surface of the chest-wall, they are sometimes slightly trouble- 

 some during operation. 



DEVELOPMENT OF THE REPRODUCTIVE ORGANS. 



The development of the internal organs of reproduction includes two distinct 

 but closely related processes, the one leading to the formation of the sexual glands, 

 the testes or ovaries, and the other to the provision of the canals for the conveyance 

 and temporary storage of the products of these glands. Provision of the excretory 

 canals is accomplished by the secondary changes and further growth of parts of the 

 Wolffian tubules and ducts in conjunction with- two additional canals — the Miillerian 

 ducts. 



References to the preceding account of the Wolffian body (page 1935) will recall 

 the constitution of the latter as including a series of transverse tubules opening into 

 a common longitudinal duct, and, further, that the Wolffian tubules comprise an 

 anterior sexual and a posterior excretory group. 



