ABSTRACT
The present investigation was conducted to evaluate the effect of the natural plant food constituent, xanthine alkaloid (caffeine), on the developing chick embryos considering both morphological and skeletal alterations. To achieve these goals, fertile eggs of Egyptian Fayoumi chicken (Gallus gallus domisticus.) were used. Eggs of the experimental group were divided into three subgroups each of which was injected through the air space before incubation with a single dose of caffeine (2, 4 or 8µg/egg). In all the tested concentrations, caffeine provoked developmental delay, decreased the extracellular matrix during cartilage deposition and decreased calcium deposits during ossification of skeleton. Skeletal alterations of various elements were accompanied with the decrease in the expression of the connective tissue growth factor at the immunohistochemical level. In the whole mount of 15-day old embryos, decreased cartilaginous and osseous deposits accompanied with teratogenicity were also observed. In addition, biochemical investigations revealed a concentration-dependent alteration in alkaline phosphatase enzyme and calcium content as a result of caffeine exposure. The results were analyzed, and compared to the control and discussed with other studies.