ACCESSORY MAMMALIAN REPRODUCTIVE GLANDS 



385 



most of the seminal sorbitol is probably de- 

 rived from the accessory glands. 



Inositol. During his studies on the vesicu- 

 lar secretion of the boar, Mann (1954b) iso- 

 lated large amounts of a crystalline, non- 

 reducing carbohydrate which he identified 

 rigorously as ?weso-inositol. This cyclic 

 polyol was found only in the seminal vesi- 

 cle, being absent from the epididymis and 

 Cowper's gland. The concentration of inosi- 

 tol in boar vesicular secretion was as high 

 as 2.6 gm. per 100 ml., and constituted as 

 much as 70 per cent of the total dialyzable 

 material therein. Using a specific microbio- 

 logic method of estimation, Hartree (1957) 

 found that in the boar, the inositol content 

 of seminal plasma was usually greater than 

 600 mg. per 100 ml., although much smaller 

 quantities (less than 60 mg. per 100 ml.) 

 were present in the bull, ram, stallion, and 

 man. In all of the species examined, the bulk 

 of the inositol in seminal plasma was in the 

 free state, and in amounts much greater 

 than those in blood or cerebrospinal fluid. In 

 most animals, seminal inositol originates 

 from the seminal vesicles, but it has been 

 detected in the prostate gland of the hedge- 

 hog, and in the ampullar secretion of the 

 stallion. 



The levels of inositol in human semen, to- 

 gether with those of fructose, are increased 

 after the administration of testosterone ac- 

 cording to Kimmig and Schirren (1956). 



The physiologic function, if any, of the 

 inositol in seminal plasma is unknown. Since 

 boar vesicular secretion, unlike other body 

 fluids of the pig, contains immense amounts 

 of inositol and very little sodium chloride, 

 j\Iann (1954b) suggested that inositol is con- 

 cerned with the maintenance of the osmotic 

 ecjuilibrium of boar seminal plasma. 



Ascorbic acid. Deproteinized extracts of 

 the seminal plasma of many species reduce 

 2,6-dichlorophenol indophenol in the cold. 

 This property has been attributed to the 

 presence of ascorbic acid in the semen of the 

 bull (Phillips, Lardy, Heiser and Ruppel, 

 1940), guinea pig (Zimmet, 1939), and man 

 (Nespor, 1939; Berg, Huggins and Hodges, 

 1941; Huggins, Scott and Heinen, 1942). 

 However, it is now established that ascorbic 

 acid does not always account for the total 

 reducing power of semen. In some animals, 

 e.g., the boar, ergothioneine is responsible in 



TABLE 6.3 

 Sorbitol and fructose content of fresh seminal 



plasma 

 In some oases the .samples represented semen 

 which had lieen pooled; the number of individuals 

 is given in brackets. (From T. E. King and T. 

 Mann, Proc. Roy. Soc. London, ser B, 151, 226- 

 2-13, 1959.) 



Number of 

 Species \ Samples Sorbitol ; Fructose 



Analyzed 



Ram. . . 

 Rabbit. 

 Bull . . . 

 Boar. . . 

 Stallion 

 Dog .. . 

 Cock... 

 Man . . . 



mg./lOO ml. 



150-600 (12) 



40-150 (4) 



120-540 (14) 



20-40 (4) 



<1 (4) 



<1 (5) 



<1 (14) 



154 (3) 



large i^art for the reduction of indophenol 

 [vide infra), and bull semen contains sulfite 

 and another, unidentified, reducing sub- 

 stance (Larson and Salisbury, 1953) . Never- 

 theless, ascorbic acid is undoubtedly present 

 in seminal plasma. Employing a specific 

 analytical method based on the formation 

 of its dinitrophenylhydrazone, ]\Iann 

 (1954a) found that the seminal vesicle se- 

 cretion of the rat, bull, guinea pig, and man 

 contains ascorbic acid in amounts varying 

 from 5 to 12 mg. per 100 ml. Mann's values 

 for the ascorbic acid content of human se- 

 men (10 to 12 mg. per 100 ml.) agree well 

 with those reported by Berg, Huggins and 

 Hodges (1941), which were based on indo- 

 phenol reduction. 



Amino sugars. After hydrolysis with acid, 

 boar semen contains considerable amounts 

 of amino sugars (Mann, 1954a). The epi- 

 didymal "semen" contains more amino 

 sugar than the vesicular secretion. 



Ergothioneine. The vesicular secretion of 

 the boar (Leone and Mann, 1951 ; Mann and 

 Leone, 1953) is a rich source of ergothione- 

 ine. This sulfur-containing base is also 

 found in the accessory glands of the Euro- 

 pean hedgehog and mole (Mann, 1956) , and 

 in the ampullar secretion of the stallion 

 (Mann, Leone and Polge, 1956). Little or no 

 ergothioneine is present in the semen of the 

 bull, ram, and man. 



Experiments with S^^-labeled precursors 

 suggest strongly that seminal ergothioneine 



