STRUCTURE OF THE VAS DEFERENS. 291 



thinner than in the adult. Wherever an internal longitudinal 

 layer is present, scattered fasciculi of smooth muscular fibres 

 from it penetrate, obliquely and longitudinally, into the 

 mucous layer, and are to be met with immediately beneath the 

 epithelium. Moreover the outermost fasciculi of the circular 

 layer decussate with those of the longitudinal at many points, 

 as may be particularly well seen at the ampulla and adjoining 

 part. Many fasciculi of the external longitudinal layer here 

 dip into the circular, in which, after pursuing an oblique course 

 for some distance, they terminate. 



On one side of the tunica adventitia of the vas deferens, and 

 arranged almost in the form of a semi-circle, are a series of 

 longitudinal fasciculi, more or less separated from one another, 

 of smooth muscular fibres that have been denominated the 

 cremaster internus by Henle. These muscular fasciculi are in 

 many parts in such close apposition to the external muscular 

 layer of the vas deferens, that it is impossible to separate them. 

 The cremaster internus is most strongly developed at the 

 commencement of the vas deferens, and progressively diminishes 

 in thickness towards the point of its entrance into the ab- 

 domen, though it increases laterally to such an extent that 

 isolated longitudinal fasciculi of smooth muscular fibres may 

 be found around the entire periphery of the adventitia. 



The nerves form a tolerably dense plexus the plexus 

 spermaticus situated on that side of the tunica adventitia 

 which is opposite to the cremaster internus. The fibres of 

 which the trunks are composed are everywhere medullated. 

 The sheath usually sends processes into the interior of the 

 nerve, dividing it into two or three subordinate fasciculi- 

 These, perhaps, correspond to the various origins from which 

 the trunks obtain their fibres, as it is well known that the 

 nerves entering the plexus spermaticus proceed both from the 

 spermatic nerves and the sympathetic. The smaller twigs 

 given off from the spermatic plexus penetrate the muscular 

 tunic and the mucous layer of the vas deferens, and may be 

 everywhere traced as medullated fibres. 



Small ganglion cells are found scattered in the upper parts 

 of the vas deferens, both in the nerves of the spermatic plexus 

 and in the more externally situated and quite isolated trunks. 



u 2 



