Bioscientifica Proceedings

The extensive use of embryo technologies has emphasized the need for assessing embryo quality by morphological techniques, such as transmission electron microscopy, immunocytochemistry for confocal laser scanning microscopy and fluorescence in situ hybridization. By a combination of these techniques, it has been possible to demonstrate: (i) that rRNA gene activation, as monitored by embryonic nucleolar development, is comparable in bovine embryos developed in vivo...

Oocyte maturation, a simple and visible phenomenon, is about to be transformed into a complex and not so visible molecular cascade leading to the marking of the following generation. The study of oocyte maturation in mammals is progressively changing towards a more molecular approach. This review addresses the main challenges in the study of RNA extraction and quantification in oocytes and embryos as well as the importance of the mRNA maturation. The identification of specific...

A tremendous amount is required of the oocyte cytoplasm to reprogramme a differentiated donor nucleus after somatic cell nuclear transfer so that it re-acquires a state of totipotency and can form a cloned individual. These reprogramming events must occur in a relatively short period after embryo reconstruction, quite unlike the situation during gametogenesis. It is remarkable that nuclear transfer can produce physiologically normal animals, but the process is highly prone to ...