ENZYMATIC DIFFERENTIATION OF MUSCLE-FIBER TYPES IN EMBRYONIC LATISSIMUS-DORSI OF THE CHICK - EFFECTS OF SPINAL-CORD STIMULATION

Myofibrillar ATPase differentiation in anterior latissimus dorsi (ALD) and posterior latissimus dorsii (PLD) muscles has been studied in chick embryo. At stage day 8, ALD fibres have acid-stable ATPase while the enzymatic activity is acid-labile in PLD fibres. In older stages, PLD exhibits α and β fibres which both have a single spot of acetyl cholinesterase (ACHE) activity. Electrical spinal cord stimulation performed for several days from day 10 of incubation leads to an increase in β fibre-type ratio in PLD, these β fibres exhibit a multiplicity of ACHE spots and are assumed to be multiinnervated. © 1979.