658 



Fishery Bulletin 89(4). 1991 



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Figure 4 



Spermatozoa in smears of reproductive organs of the school shark Galeorhinus galeus, from Rio Grande do Sul, Brazil. (A) testis, 

 (B) epididymis, (C) seminal vesicle, (D) nidamentary gland of an adult nongravid female with mature ovary. Scale bars represent 

 20 urn. 



average of 90 g. Thus, the increase of gonad weight 

 with body size reflects mostly growth of the testes, and 

 can be interpreted in terms of sexual development. The 

 gonadosomatic index varied about the mean of 0.6 at 

 total lengths less than 117 cm, and 0.9 at greater body 

 lengths. The attainment of sexual maturity, as indi- 

 cated by the clasper, was accompanied by a marked in- 

 crease in relative weight of the testes. Growth of the 

 testes continued after the attainment of sexual matur- 

 ity, as indicated by gonad weights of 35-60 g at 1 15 cm 

 TL, and 75-130g at 145cm TL. 



Smears of the testes showed that sperm occurred 

 in bundles within the testicular ampullae (Fig. 4A). In 

 the epididymis, sperm occurred singly (Fig. 4B). The 

 head of the spermatozoon measured, on average, 47^m 

 and the tail about 100/^m (n 62). In all smears of the 

 seminal vesicle, sperm occurred in circular or oblong 



agglomerations, with their heads towards the center 

 (Fig. 4C). Such structures were called spermatophores. 

 The shortest and longest axes of the spermatophores 

 measured, on average, 142 and 201 /^m, respectively 

 (n 64). 



Sexual development of the female 



The female has one functional ovary, situated on the 

 right. Ovarian follicles were visible to the naked eye 

 at total lengths greater than 80cm. Follicle color varied 

 with its diameter: transparent and colorless, up to 0.6 

 cm; opaque white, 0.4-1.2cm; pale to sulphur yellow, 

 1.0-2. 5 cm; and golden yellow, 3.5-5.5 cm. Follicles of 

 ovulating females ranged from 4.6 to 5.5 cm, which is 

 therefore the size range of the mature follicle. The 

 weight of 58 mature ovaries increased with body size 



