BackgroundQuality control programs are necessary to maintain good clinical practice. Embryo grading has been described as one of the external quality assurance schemes. Although the evaluation of embryos is based on the assessment of morphological characteristics, considerable intra- and inter-observer variability has been described. In this multicentre study, the variability in the embryo evaluation has been evaluated using morphological characteristics on day 1, day 2 and day 3 of embryo development.MethodsFive embryologists of four different IVF centers participated in this study. Multilevel images of embryos were presented on a website at different time points to evaluate intra-and inter-observer agreement in the assessment of embryo morphology. The embryos were evaluated on day 1, day 2 and day 3 of their development and each embryologist had to decide if the embryo had to be transferred, cryopreserved or discarded.ResultsBoth intra-observer agreement and inter-observer agreement were good to excellent for the position of the pronuclei on day 1, the number of blastomeres on day 2 and day 3 and the clinical decision (transfer, cryopreservation, discard). For all other characteristics (size of pronuclei, presence of cytoplasomic halo, degree of fragmentation and size of blastomeres) the intra- and inter-observer agreement was moderate to very poor.ConclusionsMono- or multicentre quality control on embryo scoring by morphological assessment can easily be performed through the design of a simple website. In the future the website design can be adapted to generate statistical feedback upon scoring and can even include a training module.

Bovine zygotes, obtained after in vitro maturation and fertilization of oocytes from slaughtered cow ovaries, were cultured in droplets of nonconditioned or conditioned medium on bovine oviduct cell monolayers. The media tested were Medium 199 alone and Medium 199 supplemented with 10% fetal calf serum (FCS). Oviduct conditioning increased both early cleavage and development to blastocysts. Only the effect on early cleavage was mimicked by FCS. The blastocysts obtained in serum-free conditioned medium (SFCM) appeared morphologically normal and had the same cell number as those produced in conditioned medium containing serum. Their hatching rates did not differ. Transfer of 16 blastocysts developed in SFCM to 16 synchronized recipients resulted in five pregnancies (31%), indicating good embryonal viability. Boiling of SFCM resulted in a total loss of activity, while heating at 56 degrees C for 30 min had no deleterious effect. A 10-kDa ultrafiltration of SFCM removed the blastocyst development-supporting activity from the filtrate but not the early cleavage-favoring activity. This allows us to conclude that at least two different factors are present in SFCM: one of low molecular mass (< approximately 10 kDa), needed to obtain the 5-8 cell stage and mimicked by FCS, and another of higher molecular mass allowing embryos to develop from the 8-cell to blastocyst stage.

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