A mathematical model also indicates that energy production in more centrally located cells of large preantral follicles may depend on anaerobic glycolysis because of the existence of a rarefied oxygen gradient from the peripheral to central layers of granulosa cells; however, it is important to consider that the availability of oxygen to the central core of preantral follicles with 3-4 layers of granulosa cells, such as class 2 human preantral follicles, may be greater than that to preantral follicles with 6-8 layers of granulosa cells. buy cipro
Therefore, energy production by the Krebs cycle due to gonadotropin and growth factor stimuli in culture is possible. Although the measurement of enzyme activity in a cell-free system under optimal and uniform reaction conditions indicates whether exogenous hormonal stimuli influence the enzyme activity per se, it is important to realize that under in vivo conditions, hormones and growth factors may also affect other factors that influence the flow of glycolysis and the Krebs cycle by acting at various levels. Further studies involving other glycolytic and Krebs cycle enzymes and intermediates may provide some information.