The changing axonal distribution in white muscle of the developing catfish, Ictalurus nebulosus (Lesueur)

The development of the peripheral innervation pattern of the axial white muscle fibres of the brown bullhead, Ictalurus nebulosus (Lesueur), was investigated utilizing silver impregnation. In the younger fish examined, axons were observed to run along the myoseptum and into the body of the myotome. With development, axons were gradually restricted to the myoseptal ends as is the situation in adult bullheads. Possible mechanisms for elimination of the superfluous axons observed in the white muscle of the developing brown bullhead are discussed.