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Purpose: To compare two different vitrification methods to slow freezing method for cryopreservation of human cleavage stage embryos., Design: Prospective randomised trial., Setting: University assisted reproduction centre., Patient(s): 568 patients (mean age 33.4 ± 5.2) from April 2009 to April 2011., Methods: 1798 supernumerary good-quality cleavage stage embryos in 645 IVF cycles intended to be cryopreserved were randomly allocated to three groups: slow freezing, vitrification with the Irvine® method, vitrification with the Vitrolife® method., Main Outcome Measure(s): Embryo survival and cleavage rates, implantation rate., Results: A total of 1055 embryos were warmed, 836 (79.2%) survived and 676 were finally transferred (64.1%). Post-warming embryos survival rate was significantly higher after vitrification (Irvine: 89.4%; Vitrolife: 87.6%) than after slow freezing (63.8%) (p < 0.001). No differences in survival rates were observed between the two vitrification methods, but a significant higher cleavage rate was observed using Irvine compared to Vitrolife method (p < 0.05). Implantation rate (IR) per embryo replaced and per embryo warmed were respectively 15.8% (41/259) and 12.4% (41/330) for Irvine, 17.0% (40/235) and 12.1% (40/330) for Vitrolife, 21.4% (39/182) and 9.9% (39/395) for slow-freezing (NS)., Conclusions: Both vitrification methods (Irvine and Vitrolife) are more efficient than slow freezing for cryopreservation of human cleavage stage embryos in terms of post-warming survival rate. No significant difference in the implantation rate was observed between the three cryopreservation methods.

Objective: To analyse treatment outcomes after SET law enforcement and to evaluate the contribution of cryopreservation in a SET policy., Material: Embryo transfer cycles performed after the law enforcement (SET period) was retrospectively compared to the cycles performed before the law enforcement (DET period)., Results: Pregnancy and delivery rates after fresh transfer of SET and DET periods were comparable (31.7% versus 33.3% and 24.5% versus 26.2%, respectively, NS). Overall twin delivery rate is significantly decreased after the law enforcement (11.3% versus 22.4%, p < 0.001) but not in patients aged 36 to 39 years (20.3% versus 24%, NS). Frozen-thawed embryo cycles allowed similar cumulative pregnancy rate (30.6%, NS). Taking into account all frozen embryos still to be transferred, SET period offers a better overall pregnancy rate than the DET period (36.1% versus 32.3%, p < 0.01)., Conclusions: The Belgian law allowed a dramatic reduction of twin deliveries especially for patients under 39 years. Cryopreservation maintains a similar cumulative pregnancy rate.

In some Ophidiiform fishes, the anterior part of the swimbladder is thickened into a hard structure called the "rocker bone", which is thought to play a role in sound production. Although this structure has been described as cartilage or bone, its nature is still unknown. We have made a thorough analysis of the rocker bone in Ophidion barbatum and compared it with both classical bone and cartilage. The rocker bone appears to be a new example of mineralisation. It consists of (1) a ground substance mainly composed of proteoglycans (mucopolysaccharide acid) and fibres and (2) a matrix containing small mineralised spherules composed of a bioapatite and fibrils. These spherules are embedded in mineralised cement of a similar composition to the spherules themselves. The rocker bone grows via the apposition of new apatite spherules at its periphery. These spherules are first secreted by the innermost fibroblast layer of the capsule contained in the rocker bone and then grow extracellularly. Blood vessels, which represent the only means of transport for matrix and mineral material, are numerous. They enter the rocker bone via the hyle and ramify towards the capsule. We propose to call this new kind of mineralised tissue constituting the rocker bone "frigolite" (the Belgian name for styrofoam) in reference to the presence of spherules of different sizes and the peculiarity of the rocker bone in presenting a smooth surface when fractured.

Most soniferous fishes producing sounds with their swimbladder utilize relatively simple mechanisms: contraction and relaxation of a unique pair of sonic muscles cause rapid movements of the swimbladder resulting in sound production. Here we describe the sonic mechanism for Ophidion barbatum, which includes three pairs of sonic muscles, highly transformed vertebral centra and ribs, a neural arch that pivots and a swimbladder whose anterior end is modified into a bony structure, the rocker bone. The ventral and intermediate muscles cause the rocker bone to swivel inward, compressing the swimbladder, and this action is antagonized by the dorsal muscle. Unlike other sonic systems in which the muscle contraction rate determines sound fundamental frequency, we hypothesize that slow contraction of these antagonistic muscles produces a series of cycles of swimbladder vibration., (Copyright 2006 Wiley-Liss, Inc.)