^t. 



eP- 







Microns 



Figure 308. — Live spermatozoon of C Virginica examined 

 under light microscope with phase contrast oil immersion 

 lens. A — acrosome; ax. b. — axial body; C — cenlriole; 

 e.p. — end piece of tail; h. — head; m.p. — middle piece; 

 mt. — mitochondrial bodies; N — nucleus; t. — tail. 



7.2-7.4 iind embedded in a mixture of three parts 

 butyl and one part methyl methacrylate. To 

 increase the contrast, some of the material was 

 placed in 1 percent alcoholic phosphotungstic acid 

 for 5 to 6 hours before embedding. The embedded 

 material was sectioned on PhUpott's microtome 



(Philpott, 1955), using a diamond knife. Since 

 the preserved pieces consisted of a multitude of 

 spermatozoa arranged in a central mass with their 

 tails pointing outward, the individual spermatozoa 

 were always cut at random in different planes, 

 regardless of how the embedded tissue may have 

 been oriented on a microtome block. The re- 

 sulting electron micrographs showed a number of 

 sperm heads cut at different planes and many 

 transverse sections of tails (fig. 309). The entire 

 structure of the head was diagrammatically re- 

 constructed by bringing various elements together 

 and placing them in their relative positions (fig. 

 310). The oval-shaped head consists of slightly 

 granular, homogeneous material covered with an 

 osmiophilic membrane made of two layers. The 

 apical portion of the nucleus is occupied by a 

 caplike acrosome of higlily osmiophilic substance. 

 The acrosome is clearly separated from the nucleus 

 by a sharply defined membrane. An egg-shaped 

 body in the central part of the nucleus extends 

 from the apex of the acrosome almost to the base 

 of the nucleus. This structure, named axial body 

 (Galtsoff and Philpott, 1960), has a central stem 

 of fibrous material which emerges from the 

 flattened bottom and extends about two-thirds of 

 the total length of the axial body. The indented 

 base of the nucleus is near the base of the axial 

 body. The caved-in space formed by this in- 

 dentation consists of material of lesser electron 

 density and extends under the nucleus to the 

 upper surface of the centriole, which is siu-rounded 

 by four mitochondrial bodies. Only two of them 

 are shown in fig. 310. 



The centriole of the sperm of C. virginica is a 

 hollow, cylindrical structure wdth walls made of 

 nine bands; these can be seen in cross section (fig. 

 311). The side \-iew (fig. 310) shows that the 

 centriole is formed in several alternating and 

 slightly constricted layers which connect with the 

 four mitochondrial bodies. These bodies have 

 the typical appearance of twisted lamallae enclosed 

 in a membrane which encompasses the centriole 

 and continues over the tail. 



The tail consists of a pair of axial filaments 

 surrounded by a ring of nine double filaments 

 spaced at equal intervals along the periphery 

 (fig. 312). The filaments are interconnected by 

 delicate strands. The axial filaments begin near 

 tlie basal plate (fig. 310) where the tail emerges. 

 Radial Iralieculae connect the ring filaments to 

 the outside wall of the tail and form nine separate 



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