Figure 1
From: Morphology and ploidy level determination of Pteris vittata callus during induction and regeneration
Scanning electron microscopy of representative Pteris vittata prothalli grown under light culture conditions for six weeks (A, C, E) and dark conditions for six weeks (B, D, F). A) Swollen prothallus with adventitious prothallus blades, rhizoids, and sex organs. Archegonia were observed, although the majority of sex organs were antheridia. B) Callus tissue forming on a swollen prothallus under dark conditions. Rhizoids were removed so that the prothallus surface could be viewed. C) Early formation of adventitious prothalli and rhizoids from antheridia-like structures. D) Callus tissue developed around antheridia cells. E) Formation of undifferentiated callus cells from the swollen prothallus. F) Fibrillar extracellular matrix covering dividing callus. Antheridia (An), callus (asterisk), extracellular matrix (arrow), groups of antheridia (chevron), rhizoids (R), adventitious prothallus blades (Pr).