Influence of exogenous transferrin on chicken skeletal muscles

The effects of transferrin (Tf) were tested in vivo using chicken embryos a s a model. Purified, iron saturated chicken serum Tf was injected intraveno usly at the 15th day of incubation in doses of 1 mg (TF1 group) and 5 mg/em bryo (TF5 group). At the 9th day after hatching, the pectoralis major (P) a nd sartorius (S) muscles were histochemically analysed for fibre type compo sition and a mitotic activity of nuclei was evaluated by the H-3-thymidine incorporation. Mean live weight as well as mean weights of P and S were non -significantly higher in both experimental groups in comparison with contro l group at the 9th day of age. Proliferation of nuclei was generally low an d very similar in ail groups (about 1.5% in P and 0.4% in S). However, the deep muscle layer of P near the clavicula (composed of fast and slow fibres ) exhibited a higher mean value (2.6%; P < 0.05) in TF1 group. In S, mean s low and fast fibre diameters were slightly larger in both experimental grou ps (significantly in TF1 only). Total number of slow fibres was reduced in TF1 and TF5 by approximately 450 and 850 fibres, respectively, in compariso n with control group. Calculated total fibre number was the highest in TF1 and the lowest in TF5. No clear differences in mean fibre type diameters we re found among groups in the superficial layer (composed of fast fibres onl y) and in the deep layer of P. Slow fibre type frequencies were reduced in the deep layer of P in both experimental groups in a similar manner as in S . Mentioned differences between experimental and control groups were mostly statistically non-significant due to individual variability. The obtained results, however, suggest that the exogenous Tf applied into the chicken em bryo could manifest a slight myotrophic effect promoting muscle growth and changing histochemical muscle composition in post-hatching chicks. To prove or exclude this possibility Further in vivo experiments are needed.