AN ULTRASTRUCTURE STUDY OF SPIROGYRA

Abstract
SUMMARY: The fine structure of three species of Spirogyra is presented, utilizing bright field, polarized light, and electron microscopes; x‐ray diffraction; and autoradiographic techniques. The birefringent filament wall consists of an outer amorphous layer covering Cellulose I microfibrils in a multinet growth pattern. Vegetative cytoplasmic fine structure is typical of the Chlorophyta with the exception of karyoids which are described. Autoradiography indicated spots on the conjugating filament walls corresponding to developing conjugation papillae. Conjugation tubes possess a cell wall of microfibrils in a reticulate pattern. During conjugation removal of papillae cross walls was observed. This wall breakdown appears to be controlled by vesicles released from the cytoplasm.