The effect of cryopreservation process on morphology and fertilising ability of Japanese quail (Coturnix japonica) spermatozoa.

Changes in the morphology and fertilising ability of Japanese quail spermatozoa were studied after semen dilution, equilibration and freezing-thawing process in order to determine the optimal diluent, cryoprotectant and the freezing-thawing method. Subsequent stages of quail semen cryopreservation caused significant decline in spermatozoa morphology and their ability to fertilise the ovum. Semen dilution with Lake's extender alone reduced the number of morphologically normal spermatozoa and decreased their fertilising ability. Dimethylacetamide (DMA) was the least detrimental but equilibration of quail spermatozoa with this cryoprotectant caused further decline in the number of morphologically normal cells. However, despite these changes, after artificial insemination with semen equilibrated with DMA 25.8 percent of fertile eggs were obtained. Further loss in the number of normal spermatozoa was observed following the freezing-thawing process. Of the two investigated freezing-thawing methods, the rapid rate (60 C/min) appeared less detrimental to spermatozoa morphology and their ability to fertilize the ovum than the "slow" rate. Also the number of sperm holes appearing in the inner perivitelline layer and the number of spermatozoa trapped in the outer perivitelline layer of the ovum was higher after the rapid than the 'slow' freezing-thawing procedure. Nevertheless, both rates did not yield any fertile eggs.