Permeability Characteristics of Ovine Primordial Follicles Calculated with Two Parameter Kedem-Katchalsky Formulation

Abstract

The osmotic responses of isolated ovine primordial follicles when suspended in various concentrations of several cryoprotective additives (CPAs) have recently been published. We have used the Kedem-Katchalsky formulation, written with two parameters as variables, to calculate permeability of the follicle membrane to water, L p , and permeability to CPAs, . By fitting the model to the osmotic responses of follicles determined by Amorim and colleagues, we were able to calculate the permeability coefficients in the presence of 0.5, 1.0, 1.5, 2.0, or 2.5 M solutions of each of the following CPAs: dimethylsulfoxide (DMSO), ethylene glycol (EG), propylene glycol (PROH), and glycerol (GLY). In the presence of DMSO, the best-fit values of L p ranged from 0.15 to 0.29 ؋ 10 ؊14 m 3 /N-sec, and ranged from 0.30 to 0.50 ؋ 10 ؊11 mol/N-sec. In the presence of EG, the corresponding values of L p ranged from 0.25 to 0.47 ؋ 10 ؊14 m 3 /N-sec, and ranged from 0.20 to 0.65 ؋ 10 ؊11 mol/N-sec. In the presence of PROH, L p ranged from 0.10 to 0.62 ؋ 10 ؊14 m 3 /N-sec, and ranged from 0.10 to 0.40 ؋ 10 ؊11 mol/N-sec. And finally, in the presence of GLY, the best-fit values of L p ranged from 0.19 to 0.32 ؋ 10 ؊14 m 3 /N-sec, and ranged from 0.05 to 0.32 ؋ 10 ؊11 mol/N-sec. The cross correlation or the reflection coefficient, , defined as ‫؍‬ 1 ؊ , where v ෆCPA is the partial mole volume of the CPA, ranged from 0.763 to 0.926 in the presence of DMSO, from 0.870 to 0.977 in the presence of EG, from 0.813 to 0.983 in the presence of PROH, and from 0.918 to 0.988 in the presence of GLY. These values of L p and (and ) can be used to predict the volumetric response of ovine follicles under arbitrary CPA loading and unloading conditions and consequently, the presumptive optimal conditions. v ෆCPA ᎏ L p 188

Cryopreservation of Preantral Follicles

“…Preantral follicles are small (usually less than 150 μm in diameter), so CPA perfusion is facilitated and optimal concentrations are easier to gauge in oocytes. Moreover, CPA types and concentrations as well as cryopreservation procedures can be precisely tailored to preantral follicles, taking into consideration their permeability parameters [63][64][65]. Another advantage of using isolated follicles is more specific to humans; in some types of cancer, there is a risk of malignant cells being present in the ovarian tissue, so transplantation is not recommended.…”

“…A physiologically normal volume is reestablished only when no natural solutes are able to leave or enter the cells [96]. In order to define the optimal CPA concentration that can induce sufficient cell dehydration and prevent damages caused by cell swelling/shrinking during CPA removal, further tests must investigate how much variation each cell type can tolerate in terms of its volume [65]. The use of non-permeable CPAs like sugars and polymers is known to help in the removal of their permeating counterparts and have a protective effect on cell membranes [32].…”