Human Gametes Cryopreservation with Cryoprotectant Modified by Egg Yolk.

The modification of cryoprotectants with an egg yolk is an effective method to improve cell survival.This study is dedicated to the comparison of four variants of cryoprotectants modified with egg yolk (commercially available and custom developed with yolk emulsion at 5.6 mg ml-1) and with lecithin.Cryoprotectant effectiveness was evaluated by cytotoxicity and vital screen tests, and by the determination of sperm motility index.A simple analytical model has been created to determine an approximate concentration of cholesterol in the solution sufficient to stabilize cellular membranes. It was shown that the average fractions of living cells, motility and membrane integrity were higher for our modification.We conclude that phosphatidylcholine (1.5 mg ml-1) contributes to the cryoprotective action of egg yolk, but doesn`t define it entirely. The cryoprotective effect of egg yolk on plasma membranes is complex, and isn`t caused by the action of one of its components.