Figure 9. . Photoreceptors of Pacific hagfish, Eptatretus stoutii.

Figure 9.

Photoreceptors of Pacific hagfish, Eptatretus stoutii. A, Schematic, showing four receptor cells (R) with outer segments (OS) protruding into the extracellular space (ES), and making contact with epithelial cells (E). Invaginating synapses are seen at the base: s, synaptic body; ave, agranular vesicles. G, glial cell. B, Outer segment lamellae are often stacked in an orderly manner. Interruptions of the kind marked by the arrow were presumed to be fixation artifacts, as they were seen only with osmium tetroxide and not with formaldehyde-glutaraldehyde. C, Lower power image, showing outer segment (OS) and connecting cilium. It is not clear whether the outer segment lamellae are enclosed by a plasma membrane or not. ES, extracellular space. The inner segment region contains an accumulation of mitochondria, analogous to the ellipsoid. D, Synaptic terminal. Within the terminal of the receptor cell (RC), a synaptic body (SB) is surrounded by vesicles, and makes contact with two post-synaptic processes (P1, P1). From Holmberg (57, 58).

From: Evolution of Phototransduction, Vertebrate Photoreceptors and Retina

Cover of Webvision
Webvision: The Organization of the Retina and Visual System [Internet].
Kolb H, Fernandez E, Nelson R, editors.
Salt Lake City (UT): University of Utah Health Sciences Center; 1995-.

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