Relation between physical properties of the zona pellucida and viability of bovine embryos after slow-freezing and vitrification

Moreira da Silva F e Metelo R

In vitro-produced bovine morulae/blastocyst embryos (n = 119) were slow-frozen and vitrified and the physical alterations of the zona pellucida (ZP) was observed by scanning electron microscopy (SEM) to find an explanation for the loss of developmental capacity of the embryos after freezing/thawing. A control group was provided, in which embryos (n = 38) were neither frozen nor vitrified. Embryos were in vitro-cultured in a standard CO2 Heraeus incubator and their viability was assessed 24 and 48 h after the start of culture, evaluating their morphological aspect. After 24 h of culture, embryo survival rate for slow-freezing/thawed (n = 23), vitrified/thawed (n = 20) and control embryos (n = 20) was 39, 27 and 90%, and 35, 14 and 65% after48 h of culture, respectively. For evaluation of physical changes occurring in ZP, 20 embryos were slow-frozen, 18 were vitrified and 18 were used as control. All embryos were fixed, dried and examined under an SEM. Embryo's diameter, as well as thenumber of pores and their diameter was measured in squares of 6.4 microm width. We observed that, on average, the diameter of the embryos (92.26 +/- 10.15 microm) did not differ significantly among all embryos. As far as the diameter of the pores inthe outer surface of the ZP is concerned, the results revealed a significant difference (P <0,05).

(In Reproduction in Domestic Animals)

Primeiro atlas português do ovócito e do embrião bovino editado este ano

O primeiro "Atlas do Ovócito e do Embrião Bovino", escrito em português, está a ser elaborado por uma equipa do Departamento de Ciências Agrárias da Universidade dos Açores. Será editado até ao final do primeiro semestre deste ano. A informação foi avançada à Agência Lusa pelo investigador Moreira da Silva, um dos co-autores do livro, que, porém, se recusa a afirmar que "é o primeiro da Europa tão detalhado", ainda que admita que "não conhece nenhum outro".

(In Ciência Hoje)