CH. LIX.] 



THE FEMALE REPRODUCTIVE ORGANS 



867 



The Spermatozoa, suspended in a richly albuminous fluid, con- 

 stitute the semen. Each spermatozoon consists of a head, a very 

 short neck, a body, a tail, and an end-piece. The head is of flattened 

 ovoid shape, and in the anterior two-thirds of its extent is surmounted 

 by a head-cap which, sharpened at its extremity, forms a cutting 

 edge. The neck is very short, and contains two centrosomes. The 

 body is about the same length as the head ; it is traversed by an 

 axial filament and a spiral fibril wound round the sheath of the 

 axial filament. More externally is a layer called the mitochondrial 

 sheath, which terminates at the junction with the tail on an annular 

 disc. The axial filament is continued through the tail into the end- 

 piece, and in the tail is surrounded by thick sheath. In some 

 animals, newts and salamanders, the tail is surrounded by a spiral 

 membrane, but this is not present in the human spermatozoon. 

 The head of the spermatozoon is formed from the nucleus of the 

 spermatid, the head-cap from the idiosome ; the centrosomes of the 

 spermatid pass to the neck, and the cytoplasm of the spermatid 

 is transformed into the parts of the body and tail of the 

 spermatozoon. 



THE FEMALE EEPRODUCTIVE ORGANS 



These consist of the two ovaries which produce ova, and the uterus 

 with the Fallopian tubes and vagina which are continuous with it. 



Fio. 554. Diagrammatic view of the uterus and its appendages, as seen from behind. The utenia and 

 upper part of the vagina have ben laid open by removing the posterior wall ; the Fallopian tube, 

 round ligament, and ovarian ligament have been cut short, and the broad ligament removed oil the 

 left side ; u, the upper part of the uterus ; c, the cervix opposite the os internum ; the triangular 

 shape of the uterine cavity is shown, and the dilatation of the cervical cavity with the rugse termed 

 arbor vit;e ; v, upper part of the vagina ; od, Fallopian tube or oviduct ; the narrow communication 

 of its cavity with that of the cornu of the uterus on each side is seen ; I, round ligament ; lo, liga- 

 ment of the ovary ; o, ovary ; i, wide outer part of the right Fallopian tube ; fl, its limbriated 

 extremity ; po, parovarium ; h, one of the hydatids frequently found connected with the broad liga- 

 ment. . (Allen Thomson.) 



The Ovary is composed of fibrous tissue (stroma) containing, 

 near its attachment to the broad ligament, a number of plain 



