The morphological and function of the metathoracic flexor tibialis muscle of Eurycantha calcarata

Abstract

The histochemical end ultrastructural results showed that, the muscle of both the male and female are a mixture of physiological fibre types, with predominantly fast fibres. The muscles are composed of fibres with different staining properties for both the ATPase and NADH-TRase activities. The AMOVA test for all ultrastructural criteria showed that the fibres population within muscles were heterogeneous, some parts being significantly different from others (p <0.001). The T-test for all criteria, with exception of the number of mitochondria in the male, also showed that most muscle parts were significantly different from each other (p-0.05). The ANOVA for all criteria, with exception of filament ratio, showed that the differences between the population of the male and that of the female is highly significant (p-0.009 for SR area and p <0.001 for others). The means of most criteria predict that the muscle of the male contains more fast fibres. The histochemical examination showed that the muscle of the male contained more fibres which stained darkly for ATPase and lightly for NADH-TR. The muscle contraction can be divided into two phases; the initial, twitch, phase was a rapid contraction with duration of 70 to 130 msec. This was followed by a slower contraction (delayed contraction) that was much longer lasting, the muscle may remain in contraction for more than 30 sec, and more variable than initial one. The maximum measured velocity of the muscles were, 17.37 mm.a*^ for the male whilst sustaining a load of 139.2 g and 11.59 ma.s~* for the female at the load of 203.6 g. The maximum initial work done was, 690.0 g.mm by the mala and 384.3 g.mm by the female. The maximum work done during delayed contraction was, 1907.6 g.mm by the male and 739.9 g.mm by the female. The maximum force produced was, 152.4 mN by the male and 30.6 mN by the female. The maximum measured power output was, 41.17 H.Kg*' for the mala and 52.01 N.Kg'^ for the female. Thr maximum measured work output by the muscles were, 3.4 J.Kg'* for the male and 4.33 J.Kg*^ for the female. Tha muscles produce relatively high power and are considered to be relatively fast with comparison to other insect muscles. The muscle of the male is faster and generates greater power output than the female. The muscle of the male produces the highest tension at the femur-tibia joint angle of 1.22 rad. The mechanical properties of the metathoracic leg and the muscle of the male also were examined.