Developmental biology research has used various avian species as model organisms for studying morphogenesis, with the chick embryo being used by the majority of groups. The focus on the chick embryo led Hamburger and Hamilton to develop their definitive staging series nearly 60 years ago and this series is still the mainstay of all laboratories working with avian embryos. The focus on the chick embryo has somewhat overshadowed the importance of another avian embryo that has proved to be equally powerful, the Japanese quail. Since the late 1960s, chimeras have been produced using chick and quail embryos and this technique has revolutionized the approach taken to the investigation of the cellular and molecular interactions that occur during development.Reviews of the literature demonstrate that many research groups are using the quail embryo in a number of established and new ways, and this species has become a primary animal model in developmental biology. Some staging of quail has been performed but this has been incomplete and variations in descriptions, stages and incubation timings mean that comparisons with the chick are not always easily made. There appears to be general agreement that, at the early stages of embryogenesis, there is little developmental difference between chick and quail embryos, although the basis for this has not been established experimentally. The accelerated ontogeny of quail embryos at mid to late stages of development means that registration with the chick is lost. We have therefore developed a definitive developmental stage series for Japanese quail so that differences are fully characterized, misconceptions or assumptions are avoided, and the results of comparative studies are not distorted.

The death of three cats, from two separate households, was linked to toxic concentrations of sodium nitrite used as a preservative in a commercial pet food. Post-mortem examination of the three cats revealed a brownish discoloration of the blood suggestive of methaemoglobinaemia. Analysis of two samples of the pet food fed to the cats revealed a mean concentration of 2850 mg of total nitrite per kg of food (as fed). In a further incident, ataxia and weakness was noticed in two of four dogs after they were fed the same brand of pet food. One dog was successfully treated for methaemoglobinaemia with intravenous methylene blue.

Osteoarthritis is a degenerative joint disease where the joint cartilage becomes damaged. Despite the ability of cranial neural crest cells (CNCC) to form cartilage in the embryo, this population of cells has been overlooked when designing cell‐based therapies for osteoarthritis and associated diseases We have begun to explore the potential of CNCC in developing tissues. A LacZ‐encoded replication‐deficient retrovial vector was used to tag explants of CNCC excised from stage 10 chick embryos before injecting into the joint regions of developing limbs of stage 18‐28 embryos. Tagged chondrocytes were subsequently identified in the developing cartilage, particularly in the region of the developing joints. The results appear to demonstrate that cranial neural crest derived cells (CNCDC) retain their ability to give rise to cartilage when implanted into the developing limb and are restricted to particular regions of the limb. The chondrocytic potential of CNCC is now being refined to investigate the integrative properties of these cells in developing and regenerating cartilage. Funded by Brighton & Sussex Medical School.

Coturnix coturnix japonica (Japanese Quail) is an avian species that has been extensively used in developmental studies for many years. Unlike the domestic chicken, Gallus gallus domesticus, the development of the quail has not been accurately staged, despite being used as an important developmental tool. The chick was accurately staged over 50 years ago in a seminal paper by Hamburger and Hamilton and although there have been several papers looking at developmental stages of the quail, the process has not been comprehensive or definitive and therefore researchers have often used the chick staging criteria. One of the most obvious and dramatic differences between quail and chick is hatching times, with the quail hatching some 4‐5 days before the chick. This more rapid developmental cycle means that the use of the Hamburger and Hamilton stage series for all quail developmental studies may not be advantageous. Therefore, we have constructed a comprehensive stage series of quail embryo development, which covers the whole incubation period. It is hoped that such a series will provide researchers with an accessible manual, when using the quail model. Funded by Brighton & Sussex Medical School.