Histological studies on the genus Fucus. V. An autoradiographic and electron microscopic study of the early stages of regeneration

Abstract

Early stages of regeneration in Fucus vesiculosus L. have been studied using segments of vegetative tissue from mature plants cultured in natural seawater. Changes in the production of sulfated polysaccharide at the wound surfaces of the segments were traced by light microscope autoradiography of applied 35SO4− at various intervals after the plants were wounded. Within 6 h after wounding, newly synthesized sulfated polysaccharide is deposited at the extensively pitted cross walls which separate wounded and unwounded filament cells. As regeneration continues, this deposition is no longer confined to the cross walls but occurs throughout the extracellular matrix adjacent to the wound surface.Thin sections of regenerating segments were prepared for electron microscopy at intervals of up to 30 days of culture. Within 24 h after wounding, a layer of microfibrils probably composed of alginic acid is deposited asymmetrically within the existing cell walls of filament cells adjacent to wounded cells. About 2 weeks after wounding, the ends of filament cells adjacent to the wound surface expand laterally in the regions of cells where the newly deposited wall penetrates the original wall. Subsequent division and growth of these cells produces a ‘plate’ of cells at the wound surface which differentiates into new epidermis and cortex.