11 



TEXT-BOOK OF EMBRYOLOGY. 



Head 



Anterior end knob 

 Posterior end knob 



Body 4 



End ring 



seen on edge, it is pear-shaped, the small end being directed forward, 

 consists mainly of nuclear material derived from the nucleus of the parent cell 

 (See Spermatogenesis.) A thin layer of cytoplasm, the galea capitis or heac 

 Acrosome cap, envelops the nuclear material, while i 



front there is a sharp edge known as tb 

 apical body or acrosome. In contrast to tr. 

 nuclear portion of the head, which of course 

 takes a basic stain, the acrosome stains wit 

 acid dyes. In some forms the acrosome i$; 

 much larger than in man and extend-, 

 forward from the head-cap as a long spea 

 sometimes barbed the perjoratorium. Thi<- 

 process perhaps assists the spermatozoon ip 

 clinging to or in burrowing its way into th 

 ovum. Many peculiar types of perfon 

 toria, for example, lance-shaped, awl 

 shaped, spoon-shaped, corkscrew-shaped, 

 have been described and have given charac 

 teristic names to the spermatozoa possessing 

 them. 



2. THE BODY in the human sperma- 

 tozoon is cylindrical and about the sam 

 length as the head. It consists of a deli 

 cately fibrillated cord, the axial thread, sur 

 rounded by a protoplasmic capsule. Ii 

 some forms (Mammals) a short clear por 

 tion, the neck, unites the head and body 

 In the neck there can sometimes be demon 

 strated an anterior end knob and one o: 

 more posterior end knobs to which is attached 

 the axial filament. In man and in sorm 

 other forms, delicate fibers spiral fibers 

 wind spirally around that portion of the 

 axial filament which lies within the body. 

 At the posterior end of the body, the axial 

 filament passes through the end disk or ena 

 ring. 



3. THE TAIL in the human spermatozoon is forty to fifty microns in length; 

 is the direct continuation of the axial thread of the body; and consists of a main 

 segment thirty-five to forty-five microns in length, and a short terminal 

 segment. As in the body, the axial filament is delicately fibrillated. Sur- 



Main segment 

 of tail 



Axial thread 

 Capsule 



Terminal 

 filament 



FIG. 8. Diagram of a human sperma- 

 tozoon. Meves, Bonnet. 



