IN-VITRO FERTILIZATION OF TRANSMIGRATED B ULL SEMEN

The fertilization capacity of transmigrated semen was tested in a bovi ne IVF-system and compared with SU semen-treatment results. Fresh seme n from a single bull and frozen-thawed semen from a single batch were alternatively used for fertilization. In the first experiment, 1072 ma tured ova were incubated for 18-20 hours in a sperm-containing medium and evaluated after aceto-orcein staining. A second experiment consist ed of the cultivation of the presumptive zygotes (n = 1040) and the ev aluation of their development after 48 and 72 h. Fertilization rates i n the TM-groups exceeded those in SU-groups, both for fresh semen as w ell as for frozen-thawed semen (8.2% and 4.5%, respectively). The diff erence was mainly due to a lower polypenetration rate. After the two c ell stages, reduced cleavage activity was noticed in cultured zygotes of the TM-groups. In comparison to the SU-method, transmigration led t o hyperactivity of sperms and negatively influenced the co-culture sys tem by damaging the cumulus-cell layers. Fertilization rates as well a s total number of cleavage stages showed no statistically supported di fference for either preparation method. The TM-preparation method was particularly impressive as it was easy to handle and required only a b rief procedure.