Hi, I work more in the human realm, but there are a lot of medically oriented articles on reptilian vision. You can search them at PubMed at http://www.pubmed.gov/

Also, I might add that survey courses tend to oversimplify as the diversity of nature is just too great to understand. I wonder if the prof was oversimplifying ? Also, being in acadmia myself, let me offer the friendly advice to choose your battles - being right doesn't mean you win.

Doing a quick search on reptiles and rods, it looks to me like it may depend on the species. A couple of examples:

Rispoli G. Navangione A. Vellani V. Transport of K by Na( )-Ca2 , K exchanger in isolated rods of lizard retina. Biophysical Journal. 69(1):74-83, 1995 Jul.

In gecko gecko 2 articles appear contradictory

Ertel EA. Modulation of guanylate cyclase and phosphodiesterase by monovalent cations and nucleoside triphosphates in light-sensitive excised patches of rod outer segments. Pflugers Archiv - European Journal of Physiology. 428(3-4):372-81, 1994 Oct.

Excised inside-out patches of vertebrate rod outer segment can support phototransduction. I have examined how ionic and metabolic conditions influence the functional properties of light-sensitive patches from Gekko gekko......

Roll B. Gecko vision-visual cells, evolution, and ecological constraints. Journal of Neurocytology. 29(7):471-84, 2000 Jul.


Geckos comprise both nocturnal and diurnal genera, and between these categories there are several transitions. As all geckos depend on their visual sense for prey capture, they are promising subjects for comparison of morphological modifications of visual cells adapted to very different photic environments. Retinae of 22 species belonging to 15 genera with different activity periods are examined electron microscopically. Scotopic and photopic vision in geckos is not divided between "classical" rods and cones, respectively; both are performed by one basic visual cell type. Independent of the activity periods of the individual species, the visual cells of geckos exhibit characteristics of cones at all levels of their ultrastructure. Thus, gecko retinae have to be classified as cone retinae. Only the large size and the shape of the photoreceptor outer segments in nocturnal geckos are reminiscent of rods; the outer segments are up to 60 microm in length and up to 10 microm in diameter. The visual cells of diurnal geckos have considerably smaller outer segments with lengths ranging from 6 to 12 microm and diameters ranging from 1.3 to 2.1 microm. Nocturnal and diurnal species differ in the structure of their ellipsoids. One type of visual cell in nocturnal geckos has modified mitochondria with either rudimentary cristae or no cristae at all, and one type of visual cell in diurnal geckos possesses an oil droplet. The visual cells of Phelsuma guentheri and Rhoptropus barnardi are intermediate between those of nocturnal and diurnal species.


In turtles
Goede P. Kolb H. Identification of the synaptic pedicles belonging to the different spectral types of photoreceptor in the turtle retina. Vision Research. 34(21):2801-11, 1994 Nov.
UI: 7975315

In this paper we describe the morphology of the different spectral types of photoreceptor pedicles in the outer plexiform layer (OPL) of the Pseudemys turtle as studied by light (LM) and electron microscopy (EM). Tangential serial thick sections were cut from the oil droplet region to the level where the axons emerge from cell bodies and then serial thin sections through the axons and the entire pedicles were collected and examined. Thus photoreceptor pedicles could be identified by tracing cells from their oil droplets to their synapses in the OPL. Double cone pedicles consisted of closely applied pairs with the principal member's pedicle wrapping around the accessory member's pedicle. Each pedicle was approx. 104 microns 2 in area and contained 12 and 8 synaptic ribbons respectively. Rods comprised 8% of the pedicles in the field, were small (84 microns 2), contained closely packed synaptic vesicles, and on average, 9 long ribbons. Single red and green cone pedicles could not be told apart without following them from their oil droplets, however, both were about the same size (106-127 microns 2) and contained 10-12 ribbons. Blue cone pedicles were small and round (80 microns 2) and arose from short oblique axons giving off from large, greenish, clear oil droplet-containing cell bodies (13% of the cone population). The least common pedicle types (5% of the cone population) were identified tentatively as UV cones because they originated from small, clear oil droplet-containing cell bodies. UV cones had spherical pedicles, elongated in the vertical axis, that arose from extremely long, angled axons. Their very small pedicles (64 microns 2) exhibited characteristic "horns" that projected from the top sides of the pedicle. Both putative UV and blue cone pedicles ended more vitread in the OPL than other pedicles and contained only 5-6 and 8-10 ribbons respectively. Understanding the ultrastructural features that distinguish the different types of photoreceptor pedicle will allow us to begin a study of spectral connections to second order neutrons in the turtle OPL in the future.

Firsov ML. Green DG. Photoreceptor coupling in turtle retina. Visual Neuroscience. 15(4):755-64, 1998 Jul-Aug.

Photoreceptors in the isolated turtle retina of two species of turtle, Chelydra serpentina and Pseudemus scripta elegans, were penetrated with double-barrel electrodes. Physiological responses were recorded through one barrel and Neurobiotin tracer was injected from the other. Intracellular injection of Neurobiotin revealed patterns of tracer-coupled photoreceptors. Both the patterns of tracer coupling and the electrophysiology suggest a high degree of specificity of connections. Rods seem to be coupled only to rods and green and red cones seem to be coupled to cones of the same spectral type. Receptive-field profiles, measured with a thin, sharply focused slit of light, often had well-defined peaks and troughs in sensitivity. We have taken advantage of this observation and used the position of a peak in sensitivity to locate the position on the retina of a coupled cell. In one rod, it was possible to correlate physiological and morphological data and to show that the peaks in the physiological receptive field occurred at positions on the retina where there were dye-coupled cells. This provides direct evidence that gap junctions produce the physiological coupling between rods.


Some others:

Jindrova H. Detwiler PB. Cyclic AMP has no effect on the generation, recovery, or background adaptation of light responses in functionally intact rod outer segments: with implications about the function of phosducin. Visual Neuroscience. 17(6):887-92, 2000 Nov-Dec.

abstract says:To evaluate the effect of the light-evoked fall in cAMP, functionally intact isolated lizard rod outer segments were dialyzed in whole-cell

Gray-Keller M. Denk W. Shraiman B. Detwiler PB. Longitudinal spread of second messenger signals in isolated rod outer segments of lizards.. Journal of Physiology. 519 Pt 3:679-92, 1999 Sep

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