Lyon, France: Evidence gathered from time-lapse recordings of the formation of early embryos (blastocysts) in the laboratory has revealed why embryos created via IVF and undergoing extended culture are more likely to develop into twins than those created via natural conception. Furthermore, the research has shown that the culture in which the IVF embryos are formed is possibly responsible for the embryos dividing into twins.
Dianna Payne, a visiting research fellow at the Mio Fertility Clinic, Yonago, Japan, told the 23rd annual meeting of the European Society of Human Reproduction and Embryology today (Monday 2 July) that about three pairs of twins per thousand deliveries occurred as a result of natural conception, but many more were born after IVF, even when only one embryo had been transferred to the mother (approximately 21 pairs per thousand deliveries). However, it was not known why this happened.
Using 33 surplus frozen-thawed embryos that had been donated for research, Ms Payne and her colleagues used computer software called MetaMorph , which creates a free-running film from single images taken every two minutes with a digital camera attached to a microscope. They then used the software to analyse data from the film.
After thawing, 26 of the 33 embryos (most of which were composed of between two and ten cells) developed to blastocyst stage in which the blastocoele is formed. This is a fluid-filled cavity in the blastocyst and is formed on about day four or five when the embryo forms tight junctions between the cells around its periphery. These outer cells (the trophectoderm) begin to pump fluid into the blastocoelic cavity where a micro-environment is formed in which the cells that will go on to develop into the body of the embryo (the inner cell mass or ICM) develop.
The time-lapse recording showed that at this stage the blastocoele collapsed at least once in 25 of the 26 embryos (96%). The frequency and degree of c
Contact: Emma Mason
European Society for Human Reproduction and Embryology