Germination of Hormocysts of Scytonema javanicum and the Function of Blue-green Algal Heterocysts

Phylogenetic Relationships of the Procaryota and the Origin of the Eucaryotic Cell

“…Thick-walled resistant endospores, of the type found in many bacteria, are also entirely absent from cyanophytes. On the other hand, the distinctive cells known as heterocysts, which are characteristic of the majority of filamentous blue-green algae (Fritsch, 1951;Allsopp, 1968;Fay et al, 1968) are never found in bacteria. In the absence of fiagella, there would be little morphological distinction between some photosynthetic bacteria and blue-green algae, but the biochemical characteristics are here conclusive.…”

Physiology and cytological chemistry blue-green algae.

“…Borzi (77) and many later workers have pointed out that the fragile junction between heterocysts and vegetative cells serves as a locus for breakage of filaments. Another "physical" function ascribed to heterocysts is that they serve as holdfasts (19,644) whereby they can, in addition, act as buttresses, permitting the branching of ensheathed filaments (461; cf. also 690).…”