Fig. 2

Morphological properties of Myxobolus klamathellus myxospore polar tubule as analyzed by SEM. a Overview of a tubule during the discharge process. The un-everted distal portion of the tubule (arrow) is still contained within the proximal everted portion (arrowhead). Top inset: enlargement of the un-everted portion (from another tubule) showing how the tubule is coiled before deployment. Bottom inset: enlargement showing the transition point between the two portions of the tubule shown in a. b-d Increasingly higher magnification views of the double spiral pattern observed on the outer surface of the tubule (arrowheads). Note the visible openings in c and d (asterisks). e Overview of a completely everted tubule demonstrating that the spiral pattern is thicker and more prominent in the proximal half. The pattern gradually disappears toward the tip. Inset shows complete lack of the pattern at the distal tip of a different tubule. a, b and e are gold-coated samples, c and d are carbon-coated. Scale-bars: 1 μm; c, 0.2 μm; d, 0.1 μm