Time-lapse technology has become a valuable and integral part of many fertility clinics. Yet for truly reliable and undisturbed embryo culture, the technology needs a specialised culture medium. We have drawn upon years of experience in research and development to offer G-TL – the first medium specifically designed for time-lapse technology.

Design phase

The G-Series™ was a natural starting point for the development of G-TL as the series is supported by studies of human physiology and the needs of embryos. The development process also applied new knowledge from metabolomics to alleviate metabolic stress and optimise the medium for continuous culture. 

Pre-clinical animal studies


G-TL has been compared to our current sequential culture system. The first study showed that G-TL gave comparable results on mouse embryo development (Fig 1). The project then progressed to transferring of mouse embryos and evaluating their viability (Fig 2). The results of implantation potential and foetal development showed no statistical difference when compared to our sequential media, G-1™ & G-2™ (Data on file).

Pre-clinical human studies

With pre-clinical animal data showing equivalent results, the next step was to use surplus human embryos donated for research. When human embryos cultured in G-TL or our sequential system were compared we found no statistical differences in embryo development.

Clinical study

TableThe final step in the development of G-TL was to verify the performance in a clinical environment using time-lapse technology. This was performed in an international, prospective, controlled and randomised multicentre study.

The study compared embryo siblings from 128 patients using a minimum of six 2PN/patient. TheTable study aimed for blastocyst culture and single embryo transfer. The primary endpoint was number of good quality blastocysts on day 5 (Fig 3). The secondary endpoints were embryo quality on day 3 as well as the total blastocyst formation and blastocyst utilisation rates.

The results showed that G-TL, when used for continuous culture in a time-lapse system, gave the same levels of embryo development and utilisation as a sequential media system (Fig 4 and 5). Preliminary data show pregnancy rates similar to those obtained in G-1 and G-2, indicating that G-TL can function well as a part of the G-Series culture system.

In conclusion, G-TL can be successfully used as a culture medium component in time-lapse systems resulting in good embryo viability. In the population receiving eSET only, outcome data showed that both sequential media and G-TL gave comparable performance on a high level, with pregnancy rates around 50%.

Watch Dr. Hardarson present results from an international, prospective, controlled and randomised multicentre study evaluating G-TL in a clinical environment using time-lapse technology. This lecture was a part of the Vitrolife Scientific Symposium at ESHRE 2014.