354 ANATOMY AND PHYSIOLOGY 



The spermatozoon is the male germinal cell (often called the 

 sperm celt). It is carried by the seminal fluid through the ductus 

 defer ens to the urethra from which the fluid is discharged. 



The ductus deferens passes upward from the testis through the 

 subcutaneous ring and the inguinal canal, then down into the 

 pelvis and beneath the bladder, where it runs forward to enter the 

 urethra. 



The spermatic cord. The testis is suspended in the scrotum 

 by the spermatic cord, which reaches from the abdominal inguinal 

 ring to the bottom of the scrotum, and contains the cremaster 

 muscle. Contraction of the cremaster muscle lifts the testis and 

 draws it upward in the scrotum (Fig. 228). 



Descent of the Testis. During fetal life the testis is situated in 

 the abdominal cavity, just below the kidney, but it slowly descends 

 to pass through the inguinal canal, reaching the subcutaneous ring 

 at about the eighth month, and at birth it should be in the scrotum. 

 It may descend more slowly, or may be arrested at any point, but 

 usually finds its place in time. 



In the scrotum it is surrounded by a double sheath of the peritoneum 

 (tunica -vaginalis) which accompanied it, and which became shut off from the 

 great peritoneal sac as the subcutaneous ring closed around it. It is a serous 

 sac, having visceral and parietal layers. 



In caring for the male infant it is important to note the condition of the 

 foreskin (or prepuce). This is a fold of skin which covers the glans penis. It 

 should be sufficiently loose to be easily drawn back, or retracted, in order that 

 careful cleansing of the parts may prevent accumulations of sebaceous mate- 

 rial, or smegma. If this is not done, irritation is caused by retained substances 

 and also by adhesions which are apt to form. 



Circumcision is cutting off the foreskin (literally cutting around}. 



Hydrocele is a collection of serous fluid in the vaginal tunic of the testis. 



Impregnation. The entrance of the spermatozoon into the 

 ovum causes impregnation or conception. The spermatozoon 

 reaches the ovum after passing through the vagina and uterus into 

 the uterine tube; it is here that conception usually occurs, in an 

 ovum which has entered the tube on its way to the uterus. The 

 head (or nuclear part) of the sperm cell unites with the nucleus of 

 the ovum to form one new or "parent cell." By division of its 

 substance this cell forms many new ones (all contained within 

 the wall of the parent cell), each composed of the united original 

 elements. A series of rapid changes follows and a re- arrangement 



