Fiber Analysis Of Lateral Line Nerve In Ctenopharygodoni Idellus, Megalobrama Amblycephala And Monopterus Albus

The fundamental structure of posterior lateral line nerve in Ctenopharyngodon idellus, Megalobrama amblycephala and Monopterus albus was firstly examined by light microscope with semithin section and electron microscope with ultrathin section. Also the structure was examined in different body lengths and different sections of the same body in C. idellus. The average transverse area, total fiber number and fiber diameter of posterior lateral line nerve were examined quantitatively by morphologic analysis system. The results show that the average transverse area in C. idellus, M. amblycephala and M. albus was 0.39, 0.432 and 0.098 mm2 respectively, the mean of total fiber number was 3315% 4944 and 1802 respectively, the mean of fiber diameter ranges was 0.9 ~ 21.1μm, 0.8 - 20.4 μm and 0.5 ~ 9.7 μm respectively, the average diameter of fibers was 6.5 μm,6.2 μm and 3.2 μm respectively, the mean of peak value of fiber diameter was 2.3 μm, 2.5 μm and 1.5 μm respectively, and the fiber diameter spectra of three fishes were all unimodal. The ratio of inner diameter to external diameter (namely d/D) was respectively 0.54, 0.54 and 0.70 in C. idellus,M. amblycephala and M. albus. Few unmyelinated fibers were seen in lateral line nerve. The total number of fibers was basically invariable in different body length of C. idellus, so was the average fiber diameter.The nerve area increased with body length because the proportion of larger fiber increased. For example, The percentage of more than 15μm in diameter increased from 2.34% to 7.03% when the fish body length increased from 21 cm - 22 cm to more than 30 cm. The nerve area decreased when the nerve extended along with body to tail because the fiber number decreased. The lateral line nerve of three fishes was charactered by myelinated fibers and larger fibers. It is considered that these features probably reflect common adaptions to aquatic enviroment.It contributes to fast conduction and response to hydrodynamic stimuli in lateral line nerve. In this paper we compare the structure of lateral line nerve of three fishes, and preliminarily study the features of how the function of lateral line nerve adapt to aquatic enviroment and living habit.