An ultrastructural study of the vegetative thallus of Collema tenax (SW). Ach, showed that although haustorial connections were absent, the mycobiont did occasionally penetrate the algal sheath material. Concentric bodies and mesosome-like structures were characteristically found in the mycobiont.
Normal and senescent blue-green algal cells were found alongside unusual vesiculating cells. Vesicles from these latter cells are apparently produced by reverse pinocytosis of plastoglobuli. These vesicles were occasionally found in close juxtaposition to the fungal hyphae, after dissolution of the algal sheath, and the hypothesis is advanced that they may be implicated in lipid transfer.‘Microtubule-like’structures were observed in the algal cells and their relationship to similar structures in free living Nostoc, other blue-green algae, bacteria, algal and higher plant chloroplasts and to typical microtubules is discussed.
The ultrastructure of fresh and rehydrated material was compared. There was no apparent difference in the ultrastructure of material which had been dried for 3 months and rehydrated and that of material which had been freshly fixed.