Origin of the Vertebrate Eye

Walls, Gordon L.

doi:10.1001/archopht.1939.00860090118018

Cited by 16 publications

(18 citation statements)

References 25 publications

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“…The question of color vision in cats is apparently still unsettled (16). It may be remarked that in the fairly extensive series of retinal sections examined in this study, the observed receptor cells were invariably rods.…”

Section: Observationsmentioning

confidence: 67%

“…The ungulates have a collagenous, acellular layer between the retina and choroid. And finally, some fish and reptiles exhibit a retinal tapetum consisting of plates or clusters of guanine crystals in the pigment epithelium of the retina (4,13,16). The present report deals with the cellular tapetum of the cat.…”

Section: Introductionmentioning

confidence: 84%

“…This is reasonable in that the pigment would defeat the purpose of the tapetum, and it is, in fact, generally observed (4) that the pigment is absent over the area of the tapetum. In the same sense, there is no fovea in the tapetalized eye (4,16) since the function of visual acuity is usurped by the tapetum. It can be seen in Fig.…”

Section: Observationsmentioning

confidence: 99%

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Electron Microscopy of the Tapetum Lucidum of the Cat

Bernstein

Pease

1959

The Journal of Cell Biology

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The fine structure of the tapetum of the cat eye has been investigated by electron microscopy. The tapetum is made up of modified choroidal cells, seen as polygonal plates grouped around penetrating blood vessels which terminate in the anastomosing capillary network of the choriocapillaris. The tapetal cells are rectangular in cross-section, set in regular brick-like rows, and attain a depth of some thirty-five cell layers in the central region. This number is gradually reduced peripherally, and is replaced at the margin of the tapetum by normal choroidal tissue. The individual cells are packed with long slender rods 0.1 /z by 4 to 5/z. The rods are packed in groups and with their long axes oriented roughly parallel to the plane of the retinal surface. Each cell contains several such groups. Cells at the periphery or in the outer layers of the tapetum are frequently seen to contain both tapetal rods and melanin granules, the latter typical of the choroidal melanocytes. Also rnelanocyte granules may have intermediate shapes. These observations plus the similar density of the two inclusions lead to the belief that the tapetal rods may be melanin derivatives.A fibrous connective tissue layer lies between the tapetum and the retina. The subretinal capillary network, the choriocapillaris, rests on this layer and is covered by the basement membrane of the retinal epithelium. The cytoplasm of the retinal epithelium exhibits marked absorptive modifications where it comes in contact with the vessels of the choriocapillaris. This fibrous layer and the basement membrane of the retinal epithelium apparently comprise the structural elements of Bruch's membrane.

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Section: Observationsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 84%

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Electron Microscopy of the Tapetum Lucidum of the Cat

Bernstein

Pease

1959

The Journal of Cell Biology

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“…The epithelium covering the ciliary processes is generally believed to give rise to the aqueous humor (Walls,(6)) and the processes have been equated on both morphological and physiological grounds with the chorioid plexuses of the cerebral ventricles (Wegefarth and Weed, (7)). The chorioid plexuses are regarded as forming the blood-cerebrospinal fluid barrier which normally restrains vital dyes, foreign particulate substances, and various metabolites from 505 entering the cerebrospinal fluid (cf.…”

Section: Discussionmentioning

confidence: 99%

“…The capillaries of the chorioid coat are believed to be the principal source of nourishment of the vertebrate retina (Walls,(6)). The deposition of silver preponderates in Bmch's membrane, although some metal is also present in the stroma and basement membranes around the flattened capillaries.…”

Section: Discussionmentioning

confidence: 99%

The Demonstration of a Blood-Ocular Barrier in the Albino Rat by Means of the Intravitam Deposition of Silver

Wislocki

Ladman

1955

The Journal of Cell Biology

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Silver nitrate administered to rats in their drinking water from 6 months to a year or more, results in generalized argyria (1). I n the central nervous system, the intravitam deposition of the silver, as revealed by histological and electron microscopical examinations (Wislocki and Leduc, (2); Dempsey and Wislocki, (3)), approximates the pattern of the hematoencephalic barrier.I n the further course of examining silver-treated albino rats, we have noriced that silver accumulates mainly in two regions of the eyes, namely, in the basement membranes of the ciliary processes and in Bruch's basal membrane between the retinal epithelium and the choriocapillary layer of the chorioid membrane. Silver also accumulates in traces, visible only with the electron microscope, in the basement membranes of the retinal capillaries. We regard the deposition of silver in these sites as manifestations of a bloodocular barrier.The purpose of this paper is to describe the deposition of silver in the several regions of the blood-ocular barrier of the albino rat, as revealed by histological examination and by the electron microscope. I n the discussion, the blood-ocular barrier will be compared with the hematoencephalic barrier. Materials and MethodsThe eyes of 4 male albino rats of the Sprague-Dawley strain, which had received 0.15 per cent silver nitrate in their drinking water for 10 and 13 months and had been maintained on a standard purina chow diet, formed the subjects of this investigation. At autopsy the eyes were excised and cut open in the equatorial plane and the lenses were removed. For histological study the anterior and posterior halves of the eyes were placed in Orth's fixative. The specimens were dehydrated, embedded in paraffau, and 5/~ sections were cut. The deparaflfinized sections were stained by the periodic acid-Schiff method and some were counterstained with Ehrllch's hematoxylin. Some of the sections were exposed to saliva for

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Rudimentary Eyes of Squamate Fossorial Reptiles (Amphisbaenia and Serpentes)

Foureaux

Egami

Jared

et al. 2010

The Anatomical Record

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The rudimentary characteristic of the eyes of fossorial animals raises some questions regarding its evolution and functionality. Would these eyes result from atrophy or from stagnated development? How would its visual function work? Anatomical investigations of these organs are the fundamental preamble to answer those questions, which are still little explored by the literature. In this article we have studied anatomical aspects of the eyes of three species of fossorial reptiles, within the suborder Amphisbaena (Amphisbaena alba, Amphisbaena mertensi, Leposternon infraorbitale), as well as a species within the ophidian suborder (Typhlops brongersmianus). The minuscule eyes (1-2 mm diameter) were visualized through a scale, a translucent area which corresponds to the spectacle. This spectacle is a thinner and transparent scale, covering a conjunctival sac. The retrobulbar space was filled with the harderian gland. The eyes of Typhlops presented an oval shape, whereas Amphisbaena specimens presented cup-shaped eyes. In Amphisbaenian sclera is comprised of cartilage, while the thin sclera of Typhlops consists of connective tissue and striated muscle fibers. The retina presented all the typical layers found in vertebrates, regardless the species. The characteristics involved in the fossil adaptation of these species include: reduced size of the eyeball, rudimentary cornea, absence of the anterior chamber, presence of a complex iris-ciliary body, and lens with amorphous nucleate cells. The analysis of the eye morphology of these animals suggests that there might be a specific function concerning light perception.

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Origin of the Vertebrate Eye

Cited by 16 publications

References 25 publications

Electron Microscopy of the Tapetum Lucidum of the Cat

Electron Microscopy of the Tapetum Lucidum of the Cat

The Demonstration of a Blood-Ocular Barrier in the Albino Rat by Means of the Intravitam Deposition of Silver

Rudimentary Eyes of Squamate Fossorial Reptiles (Amphisbaenia and Serpentes)

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