Electrophysiological properties of the follicle wall in the pig ovary

Characterization of ovarian follicular fluids of sheep, pigs and cows using proton nuclear magnetic resonance spectroscopy

Proton NMR spectra were produced for Graafian follicular fluids obtained by aspiration from sheep, pig and cow ovaries. The following low molecular mass, non-protein-bound metabolites were detected at concentrations exceeding 0.1 mM: acetate, alanine, creatinine/creatine, glycine, D-3-hydroxybutyrate, lactate, valine. Glucose was difficult to quantify and N-acetyl sugars gave a broad resonance at 2.06 ppm, presumably representing side-chains of glycoproteins. Ethanol was detected at up to millimolar concentrations in some specimens, though the physiological significance of this finding was not clear. The concentrations of all metabolites were comparable to those of plasma. These results have therefore shown that NMR spectroscopy is useful for gaining a broad and semiquantitative impression of the more abundant metabolites in the fluids of preovulatory Graafian follicles.

Physicochemical properties of follicular fluid and their relation to in vitro fertilization (IVF) outcome

Despite the limited data that are available concerning FF physicochemical properties, the following conclusions can be drawn. (1) FF temperature is lower than ovarian stroma and body temperatures. The physiological significance of this gradient is unknown. (2) Follicular size increases exponentially prior to ovulation. The relationship between FF volume and successful IVF outcome is well established. (3) A highly significant association exists between fertilization (but not embryo cleavage) and FF spectrophotometric absorbance at delta optic density of 455 nm. (4) FF behaves as a non-Newtonian fluid--its viscosity changes at different shear rates. Neither FF viscosity nor its refractive index was found to correlate with the presence of oocytes, their maturation grade, or their fertilizing capacity. (5) FF osmolarity is similar to that of the plasma. There is no information linking variations in FF osmolarity to IVF outcome. (6) FF pH is acidic, probably due to acid mucopolysaccharides. It appears that the intact follicle is capable of buffering any carbon dioxide which diffuses through its wall at the time of intraperitoneal insufflation. The transvaginal aspiration technique eliminates any possible effect of exogenous gas on FF pH. (7) Regarding the intact follicle, it was shown that (a) there is a small potential difference across the follicle wall, and (b) intrafollicular pressure remains steady prior to ovulation. This information may shed some light on mechanisms underlying FF formation and ovulation. No experiments relating these properties to IVF outcome have been performed.