URETHRA. 



1251 



varies in depth in different parts, and is thicker layer. This longitudinal fibrous layer of the 



in the membranous than in other parts of the prostatic part is connected, internally to the 



urethra. When examined with the micro- sphincter vesicae, by a thin and indistinct layer 



scope, it presents abundant evidence of the of fibres with some of the longitudinal mus- 



existence of contractile fibre mixed with com- cular fibres of the bladder ; but by far the 



mon elastic tissue. The relative quantity of greater part of it is unconnected with this 



these elements varies according to situation : latter : it consists of half fibro-cellular tissue 



thus, in the membranous portion, there is less with many nucleus-fibres, and half of evident, 



of the contractile tissue than in the spongy smooth, muscular fibres with characteristic 



portion ; a circumstance of some interest, as, nuclei. After this, and external to it, follows, 



this part being surrounded by a distinct mus- secondly a strong layer of yellowish circular, 



cular covering, there would be less necessity fibres of muscular and elastic tissue. This 



for it than in other situations where muscle layer is connected above with the sphincter 



is absent. The bloodvessels from the spongy vesica?, where also it is most developed ; whilst 



body shoot through it. This contractile tissue below it becomes gradually thinner, and below 



is identical with that recently described by the caput gallinaginis is either lost, or appears 



Kolliker as entering into the structure of the only in very small quantities. On removing 



spleen and mucous canals, which have an the several muscular layers, we come at last 



evidently contractile power. 



to the proper glandular tissue of the prostate, 



The existence of this layer has been long of which individual lobes penetrate among 

 recognised, and the attention of anatomists the circular fibres just mentioned, their ex- 

 cretory ducts' passing through the longitudinal 



was directed specially to it by Sir E. Home, 



who believed it to be muscular ; and his 

 opinion was supported by the observations 



fibres. 



In the membranous part of the urethra the 



of Mr. Wilson, who attributes the resist- smooth muscular tissue is less developed, 



ance occasionally, in irritable states of the Under the mucous membrane, whose cellular 



urethra, offered to the introduction of the tissue is remarkable for abundance of elastic 



catheter, and the expulsion of bougies in like fibres, there is a layer of longitudinal fibres, 



conditions, to spasm of these supposed mus- which are connected with those of the pro- 



cular fibres. This idea, however, was opposed static portion. These fibres consist for the 



by Sir Charles Bell; but the dispute is de- most part of fibro-cellular tissue with nucleus- 



prived of its interest since the discovery by fibres, and include, in smallnumbers, undulating, 



Kolliker of the true nature of this peculiar delicate, and curved contracting fibre-cells (of 



tissue, which combines to a certain extent the the nature of smooth muscular fibres), which 



attributes of organic muscular fibre and elastic may be, in part, isolated ; and are from 0'07 to 



tissue. This layer varies in depth in different O'l of a line long, from 1'002 to 0-003 wide, 



subjects, and is generally highly developed in They contain small nuclei from 0'012 to 0'014> 



the robust and muscular, so as in some in- long, and are more easily found in recent 



dividuals to grasp with considerable firmness specimens than in those treated with acetic 



a bougie when introduced into the canal, acid. External to these longitudinal fibres 



Wilson mentions an instance of a gentleman there is a strong layer of transverse fibres, 



who could " as distinctly feel a contraction which belong for the most part to the mus- 



of the passage coming on, and taking place at culus urethralis. Some of these, however, 



one part, as he could feel any muscle act." especially those belonging to the inner layer, 



The use of this layer must necessarily be to display some strong bundles of smooth mus- 



regulate the force of the current of fluids cular fibres, together with fibro-cellular tissue 



through the urethra. 



and nucleus-fibres, and a partial mixture of 



According to Kolliker the following is the fasciculi of the transversely striated fibres of 



arrangement of the submucous layer in various the musculus urethralis. 



parts of the urethra. It is termed by him The smooth muscular fibres are generally 

 the simple muscular tissue. " Its relations still less developed in the spongy portion of 

 are most complicated in the prostate gland, the urethra. In some cases they appear in 

 and the prostatic portion of the urethra, exactly the same manner as the longitudinal 

 which is rich in muscular fibres. So large is fibres in the membranous portion ; in other 

 the quantity of this tissue in the gland itself, cases, longitudinal fibres may be seen, but no 

 that the true glandular structure constitutes muscular tissue can be found mingled with 

 scarcely one third or one fourth of the whole, the cellular tissue and nucleus-fibres of which 

 On removing the mucous membrane from the they consist. At a certain depth, however 

 prostatic portion of the urethra, the yellow some longitudinal fibres are distinguishable, 

 longitudinal fibres of the caput gallinaginis with a more or less considerable admixture 

 come first into view, which form the lower of smooth muscle, which fibres cannot be re- 

 end of the trigone, and contain very few mus- garded as beams of the corpus cavernosum 

 cular fibres. On both sides of the caput gal- urethrse (corpus spongiosum), since they have 

 lina^inis, and extending to the anterior wall no venous spaces between them, but rather 



form a continuous membrane, which limits 

 corpus cavernosum urethra? towards 

 One might con- 



towards the membranous part of the urethra sider this part as belonging to the corpus 

 they gradually decrease to a very delicate cavernosum urethras ; in which point of view 



4L 2 



of the urethra, similar yellowish longitudinal 



fibres present themselves, and form a strong the 



layer towards the neck of the bladder; but the mucous membrane. 



