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Plate XXIV. A, portion of seminiferous tubule of rat, showing formation 

 sperm cells. Note the peculiar hook- or halberd-shaped heads and long tails of tl 

 rat's sperm cells (form of human sperm cells shown in Fig. 7). Magnified 600 time 

 From specimen lent by K. E. Mason. B, portion of seminifierous tubule of unde 

 scended (cryptorchid) testis of pig. Note that sperm cell formation is totally 

 absent, the tubule being lined by ill-defined cells (epithelial cells). The interstitij 

 cells are, however, well preserved. Magnified about 600 times. 



