The Two Components of Semen 1 3 



the galea capitis can be conveniently followed by the India-ink 

 staining technique of Blom (Fig. 3) whose studies indicate that the 

 phenomenon occurs most frequently in degenerating spermatozoa, 

 for example, in ejaculates obtained after long periods of abstinence. 

 When stained by the Gomori technique, the galea capitis or at least 

 the region near the tip of the head, shows a positive reaction for acid 

 phosphatase. On the whole, however, phosphatase activity, 'acid' 

 and 'alkaline' alike, is much more intense in the seminal plasma 

 than in the spermatozoa. Moreover, as it is rather difficult to 



Fig. 3. Schematic representation of the head of a bull spermatozoon before 

 and after detachment of the galea capitis {India-ink method). 



a, pars posterior, b, pars intermedia, c, pars anterior with the galea capitis 



in situ, q, the 'bare' pars anterior after detachment of the galea, Cg, galea 



capitis detached from the head. 



(Blom, 1945) 



remove from the spermatozoa, even by exhaustive washing, all 

 adhering traces of seminal plasma, the possibility of contamination 

 with plasma phosphatase must be taken into account when con- 

 sidering the occurrence of phosphatase in the spermatozoa themselves. 

 The narrow region which connects the sperm-head with the 

 middle-piece is known as the neck (or neck-piece), which is the most 

 vulnerable and fragile part of the spermatozoon. The entire neck 

 region is bounded, however, by a membrane which continues over 

 the head and middle-piece. In the neck, close to the base of the 

 sperm nucleus, is situated the centrosome which marks the beginning 

 of the 'axial filament', the central core of both the middle-piece and 

 tail. The axial filament consists of a number of fine long fibrils which 



