Abstract：Growth hormone is one of the most important endocrine hormones that can affect animal growth. In order to explore the influence of exogenous growth hormone on growth, skeletal muscle hyperplasia and hypertrophy of Nile tilapia (Oreochromis niloticus), the same batch of young fish were seperated into two groups: The experimantal group which was injected with exogenous recombinant human growth hormone(hGH) in muscle once a week, and the control group which was injected with phosphate buffer(PBS) only. The body length and weight of the fish were measured weekly, skeletal muscle fibers number and area in the first dosal myomere were analysed by means of paraffin tissue sections once every two weeks. The results showed that: (1) Body length and weight of the experimental group were bigger than that of the control group since the first week, but the difference was not significant(P＞0.05). however, significant variation were observed from the 5th and 7th week for body weight and body length(P＜0.01 or P＜0.05), respectively. (2) Fibers number and area in the experimantal group were also bigger than that in the control group since the first week, exogenous hyperplasia and hypertrophy were detected obviously in the experimental group from the 5th week (P＜0.01). These results suggested that exogenous growth hormone can promote growth in body length, body weight, as well as in skeletal muscle, hypertrophy growth is more dominant than hyperplasia growth in skeletal muscle growth of Nile tilapia.
