Vitrification of cattle embryos by direct dropping into liquid nitrogen and embryo survival after nonsurgical transfer
1991
Riha, J. (Vyzkumny Ustav pro Chov Skotu, Rapotin (CSFR)) | Landa, V. | Kneissl, J. | Matus, J. | Jindra, J. | Kloucek, Z.
The procedure of preserving seven days old bovine embryos by vitrification with direct dropping into liquid nitrogen is described in the paper. The intact embryos, obtained non-surgically from superovulated donors, were equilibrated for 10 minutes in the PBS medium with 10 per cent glycerol and 15 per cent growth protein of lyophilized calf serum and for another 1 to 1.5 minutes in the vitrification medium (30 per cent glycerol, 20 per cent foetal serum and 50 per cent of 2M solution of sucrose in distilled water - stock solution prepared by dissolving 65.5 g of sucrose in 57 ml of redistiller water at 60 degrees C with pasteurization for 30 minutes). After that, the embryos were dropped by means of a handling capillary from a height of 5 to 7 cm into liquid nitrogen where they were preserved in the form of drops. To thaw the frozen embryos, the embryo drop was put into a drop of the m-T 199 medium with 20 per cent FCS with a 1M content of sucrose and was left there for three minutes, and then into medium with a 0.5M content of sucrose where it was left for seven minutes. This was followed by three washings in fresh cultivation medium m-T 199 with 20 per cent FCS. Within 40 minutes the embryos were transferred to the synchronized recipients. The survival rate was 57.9 per cent (95/55 in the experimental conditions and 50 per cent (80/40)in farm conditions; the overall survival was 54.3 per cent (175/95). The survival of the fresh control embryos was insignificantly higher: 58.7 per cent (63/37, P0.05). The described procedure is a method of bovine embryo cryopreservation that saves labour, material and money; within the embryo transfer programme, such a method can be easily practiced even in improvised conditions.
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