566 , MANUAL OF HISTOLOGY. 



Those concentrically laminated concretions known as prostatic calculi 

 are composed of this substance. In old men almost every prostate con- 

 tains some of these bodies, which are often seated in the excretory ducts. 



The sinus prostatica or, as E. Weber has named it, the uterus masca- 

 linus, is a slender saccule, from 7 to 14 mm. in length, lying in the sub- 

 stance of the prostate. Like the coliculus seminalis it is lined with laminated 

 epithelial plates, has a fibrous wall intermixed with muscle elements, and 

 is enveloped in a thin layer of cavernous tissue. It opens at the summit of 

 the colliculus seminalis between the two orifices of the ejaculatory 'ducts. 



Cowper's glands are small, round, and more or less lobulated bodies, a 

 few lines broad. They possess a fibrous envelope, containing some 

 isolated bundles of striped muscle, and present the usual structure of race- 

 mose glands. In their lobules, which are separated from one another by 

 connective-tissue mixed with contractile fibre-cells, we find small gland 

 vesicles lined with columnar cells. The somewhat wide ducts of the 

 lobes are clothed with flattened cells. In the interior of the organ they 

 unite to form a number of large passages, which give to a transverse 

 section of the organ an appearance as though sacculated. Subsequently, 

 however, they combine at acute angles to form one single trunk. 



287. 



There still remain to be considered the urethra and copulative organ 

 of the male. 



The first of these consists, as is well known, of three portions, the pars 

 prostatica, passing through the prostate gland ; the p. membranacea, a 

 middle portion, made up of an independent membrane ; and a third com- 

 pound part, which is the longest of the three, and named p. cavernosa. 

 This latter belongs to the penis, in which it is enveloped in a spongy 

 body, the corpus cavernosum, s. spongiosum urethrce, which forms with its 

 anterior extremity the glans penis. Associated with this spongy mass are 

 two other structures of a similar nature, the corpora cavernosa penis, 

 which, together with an external covering of skin and several voluntary 

 muscles (m. m. ischiocavernosi and bulbo-cavernosi), make up the copulative 

 organ of the male. 



The urethra of man presents for consideration, internally, a mucous 

 membrane, covered in the prostatic and membranous portion with flattened 

 or transition cells, but lower down with cylinder epithelium ( 91). 

 This mucosa is invested, again, in a fibrous tunic, rich in elastic elements 

 and of looser texture, in whose interstices a cavernous tissue is formed 

 (Henle). External to this, again, is a layer of involuntary muscular tissue 

 formed of longitudinal fibres internally, and transverse externally. 

 The three portions must, however, be considered separately. 

 The first thing which strikes the observer in the prostatic portion is 

 the prominence of the colliculus seminalis, to which we have already 

 referred in speaking of the ejaculatory ducts and prostate. It is covered 

 by a longitudinally wrinkled mucous membrane, and consists of elastic 

 tissue (intermixed with bundles of contractile fibre-cells), which bears all 

 the characters of cavernous substance. This spongy tissue is near the 

 surface displaced at certain points by glands similar to those of the pros- 

 tate, situated partly in the mucosa and partly deeper (Henle). The 

 mucous membrane of the pars prostatica is seen to be arranged in fine 

 intersecting folds, chiefly, however, longitudinal : it contains glandules 

 identical with those just mentioned. 



