1 72 The Biochemistry of Semen 



choline liberated after ejaculation exceeds considerably the simul- 

 taneously formed inorganic phosphate. Following up this observa- 

 tion, the French investigators accomplished in 1952 the isolation of 

 a second natural precursor of choline, namely glycerylphosphoryl- 

 choline, from the seminal vesicle secretion of rats; the isolation and 

 identification was performed as a ferric chloride compound (Dia- 

 ment, Kahane and Levy, 1952, 1953). A similar result was obtained 

 by Lundquist (1953) from his studies on the secretions of the seminal 

 vesicles in rat and guinea-pig and the glandula vesicularis of rabbit. 



H,C— OH 



HC— OH O 



HgC— O— P— O— CH2 CH2N+ 



O CH3I CH3 



CH3 



Glycerylphosphorylcholine 



Physiological function of free and bound choline 



The occurrence of choline, phosphorylcholine and glycerylphos- 

 phorylcholine in semen and in the accessory secretions naturally 

 raises the problem of their physiological function. One possibility 

 which merits serious attention, is that these compounds may be 

 bound up specifically with the metabolism of phospholipids in 

 either the male accessory organs or in the spermatozoa. 



The general importance of choline in the lipid metabolism of 

 animals was first brought to light in 1932 when Best and his co- 

 workers demonstrated that the appearance of the 'fatty livers' in 

 rats fed a choline-deficient, high-fat diet, could be prevented by 

 dietary supplements of choline. Researches which followed estab- 

 lished two principal functions of choline, the lipotropic activity and 

 the stimulating action on the turnover of phospholipids. In 1939, du 

 Vigneaud and his co-workers discovered that choline is an important 

 dietary source of methyl groups for the living animal, and this led 

 to the recognition of choline as a participant in transmethylation 

 processes. These three fundamental functions probably represent 

 the clue to the understanding of the manifold symptoms associ- 

 ated with choline deficiency. Among the various manifestations of 



