[Microencapsulation in Na-alginate and in vitro development of sheep blastomeres]. / Microincapsulazione in Na-alginato e sviluppo in vitro di blastomeri di ovino.

Embryos at 4 cell stage obtained from Sarda ewes superovulated with FSHp (Sigma) were micromanipulated in order to obtain single blastomeres (1/4 E). The 1/4 E have been located randomly in two groups. In the first (Group A n. 30) the 1/4 E have been put back in empty zonae pellucidae; in the second (Group B n. 21) they have been microencapsulated in sodium alginate (1.1%) by dropping cell-alginate solution in a 1.5% CaCl2. Each capsule (1 mm diameter) contained four 1/4 E. The blastomeres have been co-cultured for 5 days in CZB medium on oviductal cell monolayer in a humidified incubator (5% CO2, 95% air, 38.5 degrees C). No differences were found between the groups reaching blastocyst stage after the end of the culture period (A 50%-B 47%).

[In vitro dissection and development of sheep embryos after preservation at very low temperature (-196 degrees C)]. / Bisezione e sviluppo in vitro di embrioni di ovino dopo conservazione a bassissime temperature (-196 gradi C).

Embryos obtained from Sardinian breed ewes superovulated with FSH-p (Sigma) were frozen at -196 degrees C in liquid nitrogen. After 6 months storage, the embryos (12, all at the compact morula stage), were thawed in a water bath at 39 degrees C for 30 minutes. Six embryos were dissected with a Leitz micromanipulator using a simplified technique. Both demi and intact embryos, were cultured in medium TCM 199 + 10% FCS at 38 degrees C in 5% CO2 for 24 hours. Only five demi-embryos (41.6%) became blastocysts versus 4 whole embryos (66.6%) after the culture period. Splitting as our results show, lowers the embryo viability after freezing-thawing, but it can be used in certain instances to obtain genetic improvement in the Sardinian breed.

[In vitro separation and development of sheep blastomeres]. / Separazione e sviluppo in vitro di blastomeri di ovino.

Four cell embryos collected by laparatomy from Sardinian breed ewes superovulated with FSH-p (16 mg Sigma), were divested of their zonae pellucidae (ZP) by micromanipulation or chemical methods (pronase 0.5%, tyrode pH 2.2). The blastomeres were separated by pipetting using a flame polished pasteur pipette in a Ca free medium (PBS. Sigma) and were inserted into previously evacuated Z.P. using a Leitz micromanipulator. The Z.P. were removed either mechanically or with acid tyrode; pronase was unable to digest them after incubation at 30 degrees C for 120 minutes. The single blastomeres were cocultured on a monolayer of ovine oviductal epithelial cells in TCM 199 + 10 FCS at 38 degrees C in 5% CO2 for 60 hours. No developments were observed in blastomeres obtained by acid digestion of the ZP while 50% of the other blastomeres continued their development until the 16 cell stages. Our results suggest that coculture with oviductal epithelial cell monolayers can support in vitro development of single ovine blastomeres.