Аннотация:The functional morphology of the various stolon sections in the colonial hydroid Gonothyraea loveni was studied on serial semi-thin cross-sections and by the method of time-lapse video microscopy. Six morphofunctional zones are identified in stolon that together provide growth and the hydroplasmic movement.
Zone 1: apical part of the growing tip (GT). Distinctive features: thickened epidermis, thin perisark, growth pulsations (GP). GP have regular period and order of intermediate phases of growth cycle.
Zone 2: subapical part of the GT with thickened gastrodermis, small lumen of coenosarc, its permanent contact with perisark. The transverse pulsations of coenosarc (TP) generate stolonic growth: significant longitudinal pulsations (LP) and elongation of GT.
Zone 3: proximal part of GT. Features: the constant contact of coenosarc with perisark remains; normal thickness of gastroderm; the enlarged lumen of gastric cavity serves for accumulation of food particles.
Zone 4: subapical part of coenosarc. Features: the largest amplitude of TP; weaker LP; the smallest concentration of non-epithelial cells in epidermis. The incoming hydroplasmic flows (HFs) are rhythmic, but weak. This site is the main driver of hydroplasm.
Zone 5: coenosarc of the first and second internodes of stolon provides accumulation and migration of specialized cells. The TP amplitude decreases, but is still high. LP weaken and lose clear rhythm. As distance from the GT increases, the speed and periodicity of HF grow.
Zone 6: areas of coenosarc removed from the GT stolon are characterized by the maximum thickness of perisarc and concentration of non-epithelial cells. Stolon branching occur here.