Lipids and their Role in the Metabolism of Semen 127 



The two principal fatty aldehydes in plasmalogens are palmitic and 

 stearic aldehydes but other fatty aldehydes were also reported 

 (Feulgen, Boguth and Andresen, 1951). Crystalline acetal phos- 

 pholipids were prepared from beef brain, and shown to belong to 

 the a-series (Thannhauser, Boncoddo and Schmidt, 1951). 



H.C— O 



\ 

 CHR 



HaC — O Acetal a-phospholipid 



I O 



I II 



H,C— O— P— O— CH, 



I 1 



OH NH2 



The plasmalogen content of bull semen as determined by Boguth 

 (1952) was found to vary from 30 to 90 mg./lOO ml.; of this about 

 two-thirds is present in the sperm and one-third in the seminal 

 plasma. The volume taken up by sperm in bull semen is compara- 

 tively small, about 10%; it would seem therefore, that the concentra- 

 tion of the acetal phospholipids in the spermatozoa themselves must 

 be of the order of 200-600 mg./lOO g. fresh weight, or 3 x lO-^" mg. 

 per cell. 



Heptacosane 



The list of interesting chemical substances which occur in semen 

 was extended again when in 1941 Wagner- Jauregg reported on the 

 isolation of the hydrocarbon heptacosane from human semen. An 

 alcoholic extract obtained from 18 litters of semen formed, upon 

 concentration in vacuo, a solid residue which was extracted first 

 with 1-5 1. acetone, and next with 2 1. of a mixture of equal amounts 

 of ethanol and ether. On purification, the acetone-soluble fraction 

 yielded some crystalline material which melted at 57-60° and con- 

 sisted, in all probability, of palmitic and stearic acid. The ethanol- 

 ether soluble fraction formed on standing a crystalline precipitate 

 containing 1 g. of heptacosane, CH3(CH2)25CH3, which on recrystal- 

 lization showed the required melting point, 59-5°. The isolation of 

 heptacosane has previously been achieved from plant material. It is 

 also known to be associated in a characteristic manner with beeswax. 



