Sporulation in the filamentous cyanobacterium Anabaena cylindrica. The course of spore formation.

Sporulation in the filamentous cyanobacterium Anabaena cylindrica involves the transformation of a vegetative cell into a thick-walled resistant structure. Because this process occurs at predictable loci in each filament and involves a significant increase in cell size, the course of sporulation in a culture can be quantitatively determined. Sporulation occurs during the late logarithmic phase of a culture, a time of slow but unbalanced growth. Under the conditions employed here, sporulation is not a synchronous event either between or within filaments. The information in this paper provides as estimate of the rate of spore differentiation and supports the previous notion that in the formation of strings of more than one spore, a gradient of spore maturation exists.