Cryopreservation is the long-term storage of viable cells/tissue in liquid nitrogen. The present study was conducted to freeze 8-cell- to morula-stage mouse embryos from the ACTREC Laboratory Animal Facility using a "slow freezing and fast revival" method. In all, 4,088 embryos were collected from 495 donor female mice of ten different strains. An average recovery of 8 embryos per donor mouse w...

XLPOU91, a POU-homeobox gene is expressed in a narrow window during early Xenopus development. We show that ectopic expression of XLPOU91 RNA causes severe posterior truncations in embryos without inhibiting the formation of Spemann's organizer. Ectopic XLPOU91 expression also inhibits mesoderm induction by fibroblast growth factor (FGF) and activin in animal cap explants. Using antisense RNA, ...

<p><strong>Background.</strong> Agaves are an important economic source in industrial products, the food and pharmaceutical industry, steroidal animal feed, ornamental plants as a material for biofuels. Despite their importance, some species present problems conventional propagation, which makes reproduction difficult has caused to be risk category. Therefore, there is need de...

Embryos and oocytes were first successfully cryopreserved more than 30 years ago, when Whittingham et al. and Wilmut separately described that mouse embryos could be frozen and stored at -196 degrees C and, a few years later, Parkening et al. reported the birth of live offspring resulting from in vitro fertilization (IVF) of cryopreserved oocytes. Since then, the use of cryopreservation techniq...

Embryos have been found in ‘old’ rocks on four continents, especially in Siberia, Nevada, Australia and China. They have been discovered in sedimentary rocks of even Late Neoproterozoic age, assuming the evolutionary geological column1 (figure 1). The Neoproterozoic is the period, so called, between 1 billion and 550 million years ago. This discovery was in the Doushantuo Formation, Guizhou Pro...

In animal embryos, morphogen gradients determine tissue patterning and morphogenesis. Shyer et al. provide evidence that, during vertebrate gut formation, tissue folding generates graded activity of signals required for subsequent steps of gut growth and differentiation, thereby revealing an intriguing link between tissue morphogenesis and morphogen gradient formation.

The handover from maternal to zygotic control has to be carefully orchestrated. In most animal embryos, maternal products drive early embryogenesis, and the genome of the zygote is only switched on later. However, in the nematode Ascaris the zygotic genome is never silent, and the maternal products are rapidly eliminated.

In animal cells, cytokinesis is mediated by the constriction of a cortical ring. In this issue, Carvalho et al. (2009) show in embryos of the worm Caenorhabditis elegans that the rate of ring constriction during cytokinesis is proportional to the initial cell perimeter, ensuring that the duration of cytokinesis is cell-size independent.

The beginning of the 21st century is marked by a great revolution supported by science, which is called biothechnological revolution and our century a biotechnological century (1). Enormous advances in biology, especially in genetics have led to homological and heterological procreation in laboratory, human genome manipulation, genetic engineering, animal but also human cloning, and scientific ...