Biochemical Evidence of Ageing in the Placenta 141 



be ascribed to the greater abundance of reduced diphospho- 

 pyridine nucleotide produced in glycolysis. Under anaerobic 

 conditions lactate production in the absence of added sub- 

 strate was about double that found aerobically. Lactate 

 production from glucose was similarly doubled. The incre- 

 ment in lactate production on the addition of pyruvate under 

 anaerobic conditions was small, again suggesting that the 

 limiting factor was the amount of reduced diphosphopyridine 

 nucleotide present. The presence of acetate or oxalacetate, 

 at levels of 10 [xmoles per ml., decreased the accumulation of 

 lactate. 



Previous experiments with 14 C -label led glycerol had shown 

 that it can be utilized by liver (Tang et al, 1953) but not by 

 muscle (Villee, White and Hastings, 1952). When slices of 

 term placenta were incubated with 14 C-labelled glycerol, it 

 was found that the placenta is unable to utilize glycerol in 

 glycolysis (Villee, 1953ft). The evidence favoured the con- 

 clusion that term placenta lacks the enzyme which phos- 

 phorylates glycerol to form a-glycerophosphate, the first step 

 in its metabolism. 



Effects of Hormones 



In another series of experiments, tests were made of the 

 ability of slices of term placenta to respond to hormones added 

 in vitro. The presence of insulin (0-5 unit per ml.) increased 

 the utilization of glucose and the synthesis of glycogen ; it had 

 no effect on the utilization of oxygen or the production of 

 lactic acid (Villee, 1953ft). Insulin also increased the rate of 

 the utilization of glucose by slices of decidua from a six- 

 week pregnancy and by slices of hydatid mole (pure chorionic 

 villi). The addition of insulin to slices of early placentas 

 increased the rate of glucose utilization to such an extent that 

 the net production observed in the control was changed to a 

 net utilization of glucose in the vessels to which insulin was 

 added. The addition of cortisone or of an aqueous adrenal 

 extract decreased the utilization of glucose and oxygen. 



