1038 THE FEMALE REPRODVCTIVE ORGAXS 



The miicons memhrane of tlie spongy urethra contains a large quantity of elastic 

 tissue and is lined hv a laminated epithelium, the superficial cells of which are 

 prismatic in ft>rm. wlnle the (lee])er lavers cover in rows of more or less longitudi- 

 nallv .lisposed papilhe. At its distal extremity tlie integumental covering of the 

 glans is inflected for about a quarter of an incli ( (> mm.), the line of demarcation 

 between the cutaneous and mucous structures being well defined. The external 

 meatus is represented bv a vertical slit about a quarter of an inch ((imm.) in 

 length, and is the least dilatable part of the canal; hence in urethral operations it is 

 sometimes necessary to enlarge it by incision. 



An examinatir»n* of the mucous surface will show a number of orifices arranged 

 in three longitudinal rows extending along the dorsal wall, and leading to short 

 tul>ular depressions which run in a l)ackward direction (towards the bladder) and 

 are called the lacun;v of Morgayni. One of these, termed the larvna magna or sinus 

 of Giierin, situated in the mesial line about an inch from the external meatus, is of 

 large size, and may arrest the point of an instrument during catheterism. It is 

 bounded bv a little fold of mucous membrane, the valvule of Guerin, and may 

 attain a depth of one-third of an inch (8 mm.). In addition to these are niany 

 simple and compound mucous glands, such as appear in the prostatic portion of 

 the canal; and the ducts of Cowper's glands open into the anterior portion of the 

 bulb on the ventral wall. 



The nuiscular coat consists chiefly of longitudinal fibres continuous with those 

 of the bladder, but a circular layer prolonged from the sphincteric fibres of the 

 membranous urethra extends as an outer layer over the bulbous portion of the 

 canal gradually disap]iearing beyond this point. 



As alreadv mentioned, the collapsed urethra is represented by a fissure. This 

 in the glans penis is vertical in direction. A short horizontal branch is superadded 

 at the upper end of the fossa navicularis, giving the fissure the aspect of an in- 

 verted T. Above this point the horizontal limb progressively elongates, while the 

 vertical limb shortens until the former alone is left, and the rest of the spongy 

 urethra is represented by a transverse fissure. In the membranous segment the 

 fissure is usually stellate, while in the prostatic region the presence of the collicu- 

 lus gives it the U-like form already described. This progressive change of shape 

 involves a kind of rifling of the tube, and prol)ably accounts for the spiral form of 

 the normal stream of urine. 



The muscular tissue of the urethra appears to be capable of a peculiar vermicu- 

 lar contraction by which a catheter left within the urethra is gradually expelled, 

 and an example is known in which an elastic instrument insecurel}' tied in situ 

 found its way, in the reverse direction, into the bladder, and formed the nucleus 

 of a calculus. 



The female urethra is described on page 1041. 



THE FEMALE ORGAXS OF GENERATION 



The female genitals may be divided into (1) an external part, the vulva, 

 representative of structures found in a more highly develoiKni condition in the 

 male; (2) a vaginal passage, the cavity of which appears as a fissure in its ordinary 

 c(Mulition, but is ca])able of very great dilatation; and (3) an internal ai)paratus 

 comiu-ising the organs of ovulation (ovaries) with their ducts, and a musculo- 

 nuicous sac (uterus) in Mhich the ovum undergoes development, and by which the 

 fcetus is ultimately expelled. The vagina and internal organs are intra-j^elvic. 



The VULVA consists of a ]iair of integumentary folds, the labia majora; two 

 smaller folds, the labia minora ; a small ])enile appendage, the clitoris ; and a 

 short passage, the vestibule, leading to the vaginal orifice. The vestibule is 



