Effect of donor strain and maturation stage of rabbit oocytes on results of penetration test of rabbit semen
Keywords:rabbit, semen, oocyte, penetration test
The objective of this work was to develop a homologous in vitre penetration test to evaluate the behaviour of rabbit sperm. Three treatments were applied to sperm (fresh, treated with heparin and frozen with a DMSO-sucrose extender), and two types of oocytes (immature or in vitre matured) belonging to tour different rabbit lines were used. The test was performed in TCM-199, under the following conditions: 37°C, 5% CO2 and saturated humidity for 6 hours. After incubation, oocytes were denuded and they were observad under microscope to record the number of sperrnatozoa/oocyte. Results obtained showed significant differences between all the treatments of sperm in the percentage of oocytes with adhered sperrnatozoa (80%, 57%, 28% oocytes with adhered spermatozoa for fresh, treated with heparin and frozen semen, respectively, P<0.05). At the same time, larger number of sperm/penetrated oocyte were observad for fresh semen than for the other treatments (21.3± 3. 7, 3.9 ± 0.6 and 2.3 ± 0.2 sperm/oocyte for fresh, treated with heparin and frozen semen, respectively, P<0.01). The resistance of fresh semen to the incubation conditions was higher than that of frozen or treated with heparin semen, which could determine the differences observed between thern in the results of the test. From the results obtained, it could be concluded that immature oocytes could be used to evaluate the behaviour of rabbit sperm, since even fresh semen were capable to adhere to the surface of these oocytes; on the other hand, further studies are necessary to improve the resistance at the incubation conditions of frozen semen, which will probably permit to predict its fertility in vivo.
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