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. 2005 Dec 1;570(Pt 3):485–499. doi: 10.1113/jphysiol.2005.100933

Figure 12. Model for water transport into oocyte.

Figure 12

Water enters the oocyte by two mechanisms. It is cotransported at a rate JH2O,co together with the non-aqueous substrates which enter at a rate of JS. Water also enters by osmosis at a rate JH2O,os determined by the osmotic gradient across the membrane (c1− c0) and the osmotic water permeability Lp. Substrate transport in the cytoplasm is described by Fick's law and an effective diffusion coefficient Di. The intracellular compartment is assumed to consist of a free fraction VF which is about 0.4 times the total volume of the oocyte, VT. The inactive fraction (VI=VT− VF) is assumed to be inaccessible to ions and water.