THE MALE AND FEMALE REPRODUCTIVE ORGANS 



1123 



halves by a median raph^ and incomplete septum. The skin, with the 

 underlying dartos, assumes a corrugated appearance under the influence 

 of cold, this effect being due to the contraction of the smooth muscle 

 cells which are scattered throughout this tissue. The activity of these 

 muscle fibers is greatly influenced by the general condition of the 

 body, their tonicity and contractility being much diminished during 

 states of depression and in old age. The areolar envelope of the tes- 

 ticle embraces scattered bundles of striated muscle which constitute 

 the so-called cremaster muscle. They are continuous with the lower 

 fibers of the internal oblique muscle, and their contraction shortens 

 the funiculus and raises the testicle. Their action is controlled by 

 the genital branch of the genito-femoral nerve. 



In cross-section each testis is seen to be enveloped by a dense fibrous mem- 

 brane, or tunica albuginea, which enters its interior as radial septa and divides 

 it into numerous compartments. These spaces are occupied by the secreting 



Fig. 533. — Diagrammatic View of the Seminiferous Tubules. 

 A, Tunica albuginea; S, septula; M, mediastinum, and vasa recta; R, rete testis; 

 E, vasa efferentia; Ep, epididymis; G, globus major; GM, globus minor; D, vas 

 deferens. 



elements, the seminiferous tubules, all of which are arranged divergently from a com- 

 mon center, formed by the vasa recta. Each tubule pursues at first a very circui- 

 tous course, but straightens out as soon as it approaches the mediastinal septum, 

 where it unites with others into from 20 to 30 straight tubes or vasa recta. The 

 latter traverse the mediastinum to form the rete testis. The total number of seminif- 

 erous tubules has been estimated at from 800 to 1000. When completely unfolded, 

 each measures from 30 to 50 cm. in length, and possesses a diameter of 0.3 mm. 

 Centrally to the rete, the small ducts again become convoluted, and unite to form 

 the vasa efferentia. In this way is formed the epididymis, a convoluted single duct 

 measuring about 7 m. in length and 0.4mm. in diameter. This collecting channel 

 descends behind the testicle to its lower border, where it passes over into the 

 z;as deferens, an ascending, rather straight tube which traverses the abdominal ring 

 and, by following the under surface of the base of the bladder, eventually termi- 

 nates in the prostatic division of the urethra. The vas deferens is about 60 cm. in 

 length and possesses a diameter of from 2 to 3 mm. 



This recurrent course of the seminal collecting tube finds its origin in the fact 

 that the testes are developed in the peritoneal cavity from the germinal epith©- 



