REPRODUCTION 



513 



majora, extend downwards and backwards on each side of a median 

 cleft, beyond which they again unite. On separating the labia 

 majora a shallow genito-urinary sinus, into which the urethra and 

 vagina open, is exposed. At the upper portion of this sinus lies the 

 clitoris, a small and very sensitive erectile organ, resembling a 

 miniature penis in structure, except that it has no corpus spon- 

 giosum and is not traversed by the uretha. From the clitoris de- 

 scend two folds of mucous membrane, the nympha or labia interna, 

 between which is the vestibule, a recess containing above, the open- 

 ing of the short female urethra, and, below, the aperture of the 

 vagina, which is in the virgin more or less closed by a thin dupli- 

 cature of mucous membrane, the hymen. 



Fia. 153. A section of a Mammalian ovary, considerably magnified. 1, outer 

 capsule of ovary; 2, 3, 3', stroma; 4, blood-vessels; 5, rudimentary Graafian fol- 

 licles; 6, 7, 8, follicles beginning to enlarge and mature, and receding from the sur- 

 face; 9, a nearly ripe follicle which is extending towards the surface preparatory to 

 discharging the ovum; a, membrana granulosa; 6, discus proligerus; c, ovum, with 

 d, germinal vesicle, and . germinal spot. The general cavity of the follicle (in 

 which 9 is printed) is filled with lymph-like transudation liquid during life. 



Microscopic Structure of the Ovary. The main mass of the 

 ovary consists of a dense connective-tissue stroma, containing un- 

 striped muscle, blood-vessels, and nerves: it is covered externally 

 by a peculiar germinal epithelium, and contains embedded in it 

 many minute cavities, the Graafian follicle*, in which ora lie. If a 

 thin section of an ovary be examined with the microscope many 

 hundreds of small Graafian follicles, each about 0.25 mm. 

 inch) in diameter, will be found embedded in it near the surface. 



