82i DEYELOPMEXT OF THE EEPRODUCTIYE ORGANS. 



akeady alluded to, which is filled with soft tissue, and is termed 2>lica (juhcrnatrix . 

 There is likewise a fibrous structui'e attached inferiorly to the lower part of the 

 scrotum, and surrounding the peritoneal pouch above, which may be distin- 

 guished as the (jul}t'rnacular cord, both this and the plica gubernatrix being 

 included in the general tei-m g uhernaciiluvi testis (J. Hunter). The gubernacular 

 cord consists of fibres which pass downwards from the sub-peritoneal fascia, 

 others which pass upwards from the superficial fascia and integmnent, and others 

 again which pass both upwards and downwards from the internal oblique muscle 

 and the aponeurosis of the external oblique ; it exhibits, therefore, a fusion of 

 the layers of the abdominal wall. Superiorly, it surrounds the processus vagi- 

 nalis, without penetrating the plica gubernatrix ; and the processus vaginalis, 

 as it grows, pushes its way down through the gubernacular cord and disperses its 

 fibres. By the time that the testis enters the internal abdominal ring, the pro- 

 cessus vaginalis has reached a considerable way into the scrotum ; and. as the 

 testis follows, the plica gubernatrix becomes shoiler, till it at last disappears ; 

 but it cannot be said that the shortening of the plica is the cause of the 

 descent of the testicle, and much less that (as has been held by some) the mus- 

 cular fibres of the gubernacular cord are the agents which effect this change of 

 position. The arched fibres of the cremaster muscle make their appearance on 

 the surface of the processus vaginalis as it descends, while its other fibres are 

 those which descend in the gubernacular cord. (See, for a further account of 

 this process, and the various views which have been held with regard to the 

 descent of the testicles, Cleland, " Mechanism of the Gubemaculum Testis." 

 Edinburgh, IS.JG.) 



The External Organs. — In the human embryo, as in that of animals, the 

 external organs are up to a certain time entirely of the same form in both sexes ; 

 and the several organs which aftenvards distinguish the male and female exter- 

 nally take their origin respectively from common masses of blastema of precisely 

 similar structure and connections. The common cloaca exists till after the fifth 

 week, and the genital emmence from which the clitoris or penis is formed makes 

 its appearance in the course of the fifth and sixth weeks in front of and within 

 the common orifice. In the course of the seventh and eighth weeks the com- 

 mon orifice is seen to become divided into two parts, viz., the longer slit of 

 the genito-urinary apeiture anteriorly, and the naiTower and more rounded anal 

 aperture posteriorly : but the exact manner in which the separation of these 

 two apertures takes place has not yet been acciu'ately traced. It -is intimately 

 connected with the formation of the urogenital cord as an independent stmc- 

 ture, and is probably mainly effected by the advance from the sides and poste- 

 riorly of septal bands which separate the lower pai"t of the intestine. Somewhat 

 later, or in the ninth and tenth weeks, a transverse integumental band completes 

 the division between the anal and the urogenital orifices, which band forms the 

 whole of the so-called perineum of the female, and the part of the perineal 

 integument in the male which is situated behind the scrotum ; the raphe being 

 most obvious in the male sex. 



The cutaneous folds, or cii-cular genital ridge, which are afterwards converted 

 into mons Veneris, labia majora, and scrotum, as well as the lips of the urogenital 

 furrow, which are converted into the nymphte of the female and unite as integu- 

 ment below the penis in the male, are both of early formation and at first pre- 

 cisely the same in all embryoes. In this condition, which continues until the 

 eleventh or twelfth week, the parts aj^pear alike in both sexes, and resemble 

 very much the more advanced female organs. The rudiments of JJartholui's or 

 Ceirpcrs glands are, it is said, seen at an early period, near the root of the 

 rudimentary clitoris or penis, on each side of the genito-ui-inary passage. 



In the female, the tvro lateral cutaneous folds enlarge, so as to cover the clitoris 

 and form the labia majora. The clitoris itself remains relatively smaller, and the 

 gToove on its under surface less and less marked, owing to the opening out, and 

 subsequent extension backwards, of its margins to form the ntjinplKP. The vas- 

 cular bulbs remain distinct and separate, except at one point where they run 

 togetlier in the glans clitoridis. The hijmcn begins to appear about the fifth 

 month as a fold of the lining membrane at the opening of the genital passage 



