570 



THE HUMAN BODY 



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. 



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 follicles, in which ova lie. If a 

 thin section of an ovary be examined with the microscope many 



FIG. 155. 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; b, discus proligerus; c, ovum, with 

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

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



hundreds of small Graafian follicles, each about 0.25 mm. (ife 

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

 These are lined by cells, and each contains a single ovum. In a 

 woman of child-bearing age there will be found also, deeper in, 

 larger follicles (7, 8, 9, Fig. 155), their cavities being distended, 

 during life, by liquid; in these the essential structure may be more 

 readily made out. Each has an external fibrous coat constituted 

 by a dense and vascular layer of the ovarian stroma; within this 

 come several layers of lining cells (9, a, Fig. 155) constituting the 

 membrana granulosa. At one point, b, the cells of this layer are 



