Eggs,embryonated hens

Viruses replicate only in living cells so the first viral vaccines were necessarily made in animals smallpox vaccine in the dermis of calves and sheep and rabies vaccines in the spinal cords of rabbits and the brains of mice. Such methods are no longer used in advanced vaccine production and the only intact animal hosts that are used are embryonated hens eggs. Almost all of the vims that is needed for viral vaccine production is obtained from cell cultures infected with vims of the appropriate strain. 

Embryonated hens eggs are still the most convenient hosts for the growth of the vimses that are needed for influenza and yellow fever vaccines. Influenza vimses accumulate in high litre in the allantoic fluid of the eggs and yellow fever vims accumulates in the nervous systems of the embryos. 

Influenza (split virion)t Allantoic fluid from embryonated hens eggs infected with influenza viruses A and B 1 Harvest of viruses 2 Disruption with surface active agent 3 Blending of components of different serotypes Assay of haemagglutinin content by immunodiffusion Inoculation of embryonated hens eggs to exclude live virus... 

All the official recommended methods for determining the ocular Irritation potential of a chemical derive from the Draize rabbit eye test (Draize et al., 1944). Despite of its historical impact, to day most scientists as well as the general public are disapproved of the Draize test for ethical and scientific reasons (Sharpe, 1985, Swanston, 1985). A number of in vitro test systems were described, e.g. the isolated eyes (Price and Anders, 1985), the embryonated hen s egg-choriallantoic membrane (HET-CAM) test (Luepke, 1985), the neutral red/kenacid blue method (Borenfreund and Puermer, 1985 Knox et al., 1986 Riddell et al., 1986), or the EYTEXR method (Martin, 1993 Regnier, 1994). 

Studies conducted in the early 1960s indicated that CN can affect critical stages of embryonic development when instilled in alcoholic solution at mM concentrations directly into cultures of hen s eggs (Mankes and Mankes, 2004). The relevance of these findings to human developmental risks is uncertain, especially since conventional developmental toxicity studies in vivo have not been conducted. 

W. D.McFarlane, H.L. Fulmer and T.H. Jukes, Studies in Embryonic Mortality in the Chick. I. The Effect of Diet upon the Nitrogen, Amino-nitrogen, Tyrosine, Tryptophan, Cystine and Iron Content of the Proteins and on the Total Copper of the Hen s Egg, Biochem. J. 24, 1611-1631 (1930). 

Lysozyme has been isolated from bovine and canine cartilages and from canine sera by a variety of chromatographic procedures, including affinity chromatography on carboxymethylchitin. The composition of the bovine lysozyme is similar to that of other mammalian lysozymes. Anti-(canine lysozyme) antibodies cross-reacted with bovine lysozyme, but with neither hen egg-white lysozyme nor embryonic chicken-cartilage lysozyme. Electron microscopy has shown that lysozyme in canine epiphyseal plates is localized extracellularly, mainly in the vicinity of the chondrocytes. Evidence that lysozyme has a physiological role in normal endochondral calcification has been presented. ... 

The hen s egg test on the chorioallantoic membrane (HET-CAM assay) enables irritant reactions to be identified that are similar to those which occur in the eye using the standard Draize rabbit eye test. In the HET-CAM test system, three reactions are determined, namely, haemorrhage, lysis and coagulation (sometimes hyperemia is also used as a parameter) of the CAM on the ninth day of embryonation when nerve tissue and pain perception have not yet developed (Figure 9.1.4). 

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