416 FEMALE URETHRA. [sect. 1 90. 



tubes, or of simple racemose glandules from the aggregation of 

 such. These glands measure o - 04'" to 024'", and have apertures 

 of 002" to o , 05'" in diameter ; they contain a cylindrical epithe- 

 lium and a clear mucus. In pathological cases, Virchoio finds 

 them to be here and there enlarged, and filled with whitish plugs 

 of mucus. 



The male urethra will be considered when treating of the sexual 

 organs. That of the female is made up of a mucous membrane 

 and a muscular layer; the former is of a red colour, being pro- 

 vided with numerous vessels, especially with well-marked venous 

 networks in the submucous tissue (Kobelt, without reason, has 

 described these as a corpus spongiosum). It has a laminated 

 pavement-epithelium, consisting of elongated cells in the deeper 

 portion, as in the bladder. The muscular fibres of the female 

 urethra are arranged, on the one hand, into thin layers running lon- 

 gitudinally and transversely, in connection with the mucous mem- 

 brane, and intermingled with much connective tissue and elastic 

 fibres ; on the other hand, they form the thick musculus urethralis, 

 whose fibres run chiefly in the transverse direction. These fibres 

 are all of the plain variety. A certain number of racemose mucous 

 glandules (Littre's glands) , the same in structure as those of the 

 bladder, only mostly larger and more compound, pour their se- 

 cretion into the urethra. Occasionally , they are found enlarged up 

 to 2 lines in size, their mucous membrane swollen and protruded, 

 and their enlarged tubes filled with a colloid substance, or even 

 with concretions resembling prostatic calculi. - 



§ 190. Physiological Remarks. Development of the Urinary 

 Organs. — In the chick, according to Remak, the kidneys are 

 formed as two hollow processes from the rectum, in which the 

 epithelial and fibrous laminae of the latter are concerned. Their 

 further growth, like that of the lungs, is by the ramification of 

 their epithelial tubes, and by the increase in size of the fibrous 

 lamina {Investigations into the Development of Vertebrata, tab. ii., 

 fig. 83 — 85). In mammalia, the first development of the kidney 

 has not yet been observed; on the other hand, the subsequent 

 changes, as we learn them from the researches of Ratlike, J. 

 Mailer, Valentin, and Bischoff, agree very well with the state- 

 ments of Remak, only that in the mammalia the tubules appear 

 to be solid at the beginning, and to be developed after the type of 

 the salivary glands. In mammalia, the kidneys consist of nothing 

 else, at their first formation, than the pelvis and a certain number 



