In comparison to spermatozoa of other mammalian species, boar spermatozoa are highly sensitive to osmotic changes. Human spermatozoa have been shown to tolerate swelling to 1.1 times their isosmotic volume and shrinking to 0.75 times their isosmotic volume and still maintain 90% motility . Studies of mouse spermatozoa indicate that they are as sensitive as human spermatozoa but more tolerant than boar spermatozoa to osmotically driven changes. Mouse sperm can shrink and swell to 0.76 and 1.24 times their isosmotic cell volume, respectively, and still maintain 80% motility . However, boar spermatozoa can tolerate swelling and shrinking only to 1.02 and 0.97 times their isosmotic cell volume and still maintain > 70% motility.
Figure 7 compares the osmotic tolerance limits for human sperm, mouse sperm, and boar sperm in the presence of an extender.
Activation Energy for Boar Spermatozoa CPA and Water Permeability
The CPAs described in this paper are thought to protect cells through their colligative properties, which maintain internal and external cellular solute concentrations at tolerable levels . However, their presence can be damaging, and what may be protective for one cell type may not be appropriate for another. For example, glycerol successfully cryoprotects bull spermatozoa; however, the same procedures for the cryopreservation of boar spermatozoa have not been as successful. buy antibiotics online
It has been demonstrated in human spermatozoa that an optimal CPA is one that can permeate the cell rapidly, thereby minimizing cell volume excursion, with low temperature dependence (activation energy) and low toxicity to the cell . The present study focused on DMSO, glycerol, and EG, and their ability to permeate boar spermatozoa. Cells were exposed to the CPAs, and changes in cell volume were measured over time. A two-parameter model was used to fit the permeability coefficients. The reflection coefficient was calculated, and a fixed value for Vb was chosen , versus fitting Vb as done in other studies . DMSO was studied at room temperature only.
FIG. 6. Cell water volume changes during cooling and warming of boar spermatozoa in the presence of glycerol (A) or EG (B) using cooling rates of 10°C/min (solid line), 100°C/min (dotted line), and 1000°C/min (dashed/dotted line), and a warming rate of 1200°C/min.
FIG. 7. The estimated normalized percentage motilities of human spermatozoa 17], mouse spermatozoa , and boar spermatozoa in the presence of extender (present paper) after exposure to anisosmotic conditions and return to isosmotic conditions.