MORPHOLOGIC AND MORPHOMETRIC CHARACTERISTICS OF LIMB MUSCLES OF THE GOAT

Use of (1) two histochemical reactions (myosin adenosine triphosphatas e, mATPase, and nicotinamide adenine dinucleotide dehydrogenase-tetraz olium reductase, NADH-TR), (2) biopsies from deep and superficial part s of muscles, and (3) different indices (percentage population, PP, vs . cross-sectional area proportion, CSAP; and lesser (LD) vs. equivalen t diameter (D)) for estimating fibre type composition or size were com pared, and data obtained on composition and size of fibre types in 25 limb muscles of goats. Both reactions differentiated types I, IIA and IIB fibres and yielded reproducible but different estimates of fibre c omposition or size. In the extensor carpi radialis muscle, mATPase sec tions yielded higher estimates of type I fibre composition (7.2 +/- 0. 1 vs. 6.5 +/- 0.1; P < 0.01) and lower estimates of type IIA fibre dia meter (45.3 +/- 1.5 vs. 48.4 +/- 1.0; P < 0.05) than NADH-TR sections. PP and CSAP yielded different estimates of composition of types I, II A and IIB fibres (7.2 +/- 0.1 vs. 6.6 +/- 0.3, 30.2 +/- 1.6 vs. 28.4 /- 1.2 and 62.3 +/- 1.8 vs, 65.0 +/- 1.4, respectively; P < 0.05) as d id biopsies from superficial and deep parts of the muscle (6.4 +/- 0.2 vs. 35.8 +/- 0.3, 26.3 +/- 5.9 vs. 54.3 +/- 4.2, and 67.4 +/- 5.7 vs. 9.9 +/- 4.5, respectively, for types I, IIA and IIB fibres; P < 0.001 ). LD and D also yielded different estimates of fibre diameter. Most l imb muscles of goats contained types I, IIA, IIB and few IIC fibres in varying compositions and sizes. Type I fibre composition ranged from 6.4% in the tensor fascia lata to over 99.7% in the soleus muscles, in creased with depth into extensor muscles and decreased with depth into flexor muscles, the latter being contrary to the pattern of fibre typ e stratification in other species. Goat muscles also differed in that mATPase and NADH-TR activities did not exhibit a reciprocal relationsh ip in types IIA and IIB fibres as in many other mammalian species. The se differences indicate caution in comparing results between studies t hat use different methods, and call for specification or standardizati on of biopsy sites and methods used to study muscle biopsies. They als o suggest that goats may differ from other species in the contractile properties of types IIA and IIB muscle fibres.