[Light and electron microscopic study of the photoreceptors of the lamprey Lampetra fluviatilis].

Photoreceptors of the retina have been investigated by electron microscopic and light microscopic techniques using differential staining. The observed differences between short and long photoreceptors suggest that the former act as the receptors of scotopic system and contain rhodopsin, whereas the latter contain presumably cone pigment and may be classified as receptors of photopic system.