MATURATION OF GAMETES 



153 



(figs. 80F-H; 81A-C; 82A-C; 85M-P). A considerable amount of mitochon- 

 drial material may also enter into the formation of tail (fig. 84). 



A peculiar, highly specialized characteristic of many sperm tails is the 

 development of a vibratile membrane associated with the axial filament (fig. 

 79E, F). Its origin is not clear, but it probably involves certain relationships 

 with the mitochondrial material as well as the cytoplasm and axial filament. 



In the formation of the human and guinea-pig sperm, the nucleus experi- 

 ences only slight changes in shape from that of the spermatid. However, in 

 many animal species, spermiogenesis involves considerable nuclear metamor- 

 phosis as well as cytoplasmic change (figs. 69, 79, 85). 



In summary it may be stated that while the various shapes and sizes of 

 mature flagellate sperm in many animal species, vertebrate and invertebrate, 



CENTRIOLE 



Fig. 85. Spermatogenesis in the common fowl. Observe extreme nuclear metamor- 

 phosis. (After Miller, Anat. Rec, 70.) (A) Resting spermatocyte. (B) Early leptotene 

 stage. (C, D) Synaptene stage. (E) Pachytene stage. (F, G) Diplotene stage. (H) 

 Diakinesis. (I) First division, primary sperm. (J-P) Metamorphosing sperm. 



