求翻译：其中一套空纤维半透膜集束中通过的是无菌O2、CO2和N2，以调节组织培养液的O2含量和pH值。另一套中通过的是新鲜培养液，向培养环路提供营养成分和透析出代谢产物，但其孔径限制了生长因子的通过。是什么意思？

Semipermeable membrane in the cluster through one empty fiber is sterile of O2, CO2 and N2, O2 concentration and pH of the tissue culture fluid to adjust values. Another set of fresh culture medium is passed in, to provide nutrients, metabolites of dialysis training loop, but its aperture limits the growth factor through.