Ethanol effect on the chick embryo ossification: a macroscopic and microscopic study

This study attempts to analyze anomalies in avian embryos induced macroscopically and microscopically when exposed to ethanol (EtOH) during the first stages of development. Fertilized chicken eggs were employed in this study. The eggs were incubated at 37.8§C. Some of the eggs were treated on day O with EtOH (20 per cent, 40 per cent and 60 per cent) by instillation in the air sac. The control group was instilled with 0.1 ml of NaCl at 0.9 per cent. Other eggs were treated on the 4th post-incubation day, employing the same methodology. The embryos in both groups were removed from eggs on the 11th incubation day and examined using a dissecting binocular micrsocope. After macroscopic analysis, the samples obtained were fixed in 10per cent formol, photographed and processed according to common histological techniques and the Picrosirius method. Embryos treated with EtOH demonstrated a significant weight decrease. Microscopic analysis by means of the Picrosirius method revealed that the intra-membranous ossification process presents less development, and therefore there wass less type I collagen in trabecular bone in the embryos post-exposure to EtOH with respect to the control.

Use of chick embryo in screening for teratogenicity.

A teratology screening system would detect agents hazardous to the conceptus before they can perturb embryonic development in humans. The back log of untested chemicals and the rate at which new substances enter the market exceed the developmental effects testing by standard in vivo method. Thus, cheaper, quicker in vitro systems afford a unique opportunity for investigating the direct interaction of substances with developing morphogenetic system (MGSs), since maternal influences are excluded. As a carrier of a complete set of MGSs, the chick embryo in ovo manifests an advantage over those in vitro systems that employ isolated embryos or embryonic tissues that have only limited survival. Under controlled experimental conditions including standardization of subjects, administration technique and mode of evaluation, according to the basic principles of teratology, the chick embryo test is demonstrated to be reliable and to afford quantifiable end points for evaluation. Individual compounds, mixtures of compounds and against and antagonist can easily be administered and tested. The chick embryo possesses its own basic enzyme-catalyzed drug-transformation capacity and moreover, it can be used for screening specific human metabolites. Different newer techniques e.g. chick embryotoxicity screening test (CHEST), Chick embryo blastoderm model etc are described in detail. Chick embryo fulfills all the criteria which a test should have at a lower level of tier system in teratological studies i.e. modest laboratory equipment, moderate skill, minimal expenditure of time and money, ease of accessibility of embryo, known embryological development, possibility of experimenting on a large scale for statistically valid results and whole animals are also not required.

Effect of noristerat on the development of the retina of the chick embryo

The present work was concerned with the development of the retina of the chick embryo and the effect of noristerat on its development, aiming for the explanation of the possible hazards of the drug which may occur to the fetus, if the pregnant mother is under the treatment with this drug. Morphological and histological studies were done on the retina of 10, 12 and 14-day old chick embryo treated on the 6th day of incubation by a dose of noristerat equivalent to the average human therapeutic dose [0.2 mg/embryo]. Retardation of growth of the retina was observed in all treated embryos as evidenced by reduction of the size of the retina, associated with disappearance of some layers of the retina