Morphological and elemental analysis of isolated incubated frog retina-choroid

1984 ◽  
Vol 42 ◽  
pp. 298-299
Author(s):  
B. J. Panessa-Warren ◽  
J. B. Warren ◽  
H. W. Kraner
Keyword(s):  
Elemental Analysis ◽  
Pigment Epithelium ◽  
Human Retina ◽  
Healthy Individuals ◽  
Anterior Portion ◽  
Pathological Conditions ◽  
Frog Retina ◽  
Isolated Retina ◽  
Vertebrate Eye ◽  
Retina Pigment Epithelium

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.

scholarly journals Enhanced Transport and Permeation of a Polymeric Nanocarrier across the Retina by Mixing with ATP upon Intravitreal Injection

Pharmaceutics ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Kiyoon Kwon ◽  
Youngmin Hwang ◽  
Junyoung Jung ◽  
Giyoong Tae
Keyword(s):  
Great Increase ◽  
Pigment Epithelium ◽  
Outer Part ◽  
Vitreous Humor ◽  
Retinal Diseases ◽  
P2y Receptor ◽  
Main Site ◽  
Tight Junction Disruption ◽  
Polymeric Nanocarrier ◽  
Retina Pigment Epithelium

The outer part of the retina pigment epithelium (RPE) in the retina is the main site of neovascularization associated with retinal diseases. However, various obstacles interrupt the delivery of medicines across the RPE, mainly due to the well-developed tight junctions in the RPE. Currently, there is no practical formulation to overcome this issue. In this study, we demonstrated that simple mixing with adenosine tetraphosphate (ATP) has the potential to greatly enhance the transport and permeation of a polymeric nanocarrier across the retina via intravitreal administration. Chitosan-functionalized, pluronic-based nanocarrier (NC), which can deliver various biomolecules efficiently, was used as a polymeric nanocarrier. Mixing with ATP facilitated the diffusion of the nanocarrier in the vitreous humor by reducing the electrostatic interaction between NC and negatively charged glycosaminoglycans (GAGs) in the vitreous humor. Mixing with ATP also allowed the penetration of NC across the whole retina, and it resulted in a great increase (approximately nine times) in the transport of NC across the retina, as well as spreading it throughout the whole retina upon intravitreal administration in a mouse model. This enhanced permeation across the retina was specific to ATP but not to GTP, suggesting the possibility of P2Y receptor-mediated tight junction disruption by ATP.

Study of hypoxia-induced expression of HIF-1α in retina pigment epithelium

2007 ◽  
Vol 143 (3) ◽  
pp. 323-327 ◽  
Author(s):  
Zeng Yanjun ◽  
Li Guangyu ◽  
Fan Bin ◽  
Wang Qing ◽  
Jie Ying ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Induced Expression ◽  
Retina Pigment Epithelium

Patterning the Vertebrate Retina with Morphogenetic Signaling Pathways

2019 ◽  
Vol 26 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Marcos J. Cardozo ◽  
María Almuedo-Castillo ◽  
Paola Bovolenta
Keyword(s):  
Signaling Pathways ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Subsequent Development ◽  
Neural Retina ◽  
Bmp Signaling ◽  
Vertebrate Species ◽  
Optic Stalk ◽  
Optic Cup ◽  
Vertebrate Eye

The primordium of the vertebrate eye is composed of a pseudostratified and apparently homogeneous neuroepithelium, which folds inward to generate a bilayered optic cup. During these early morphogenetic events, the optic vesicle is patterned along three different axes—proximo-distal, dorso-ventral, and naso-temporal—and three major domains: the neural retina, the retinal pigment epithelium (RPE), and the optic stalk. These fundamental steps that enable the subsequent development of a functional eye, entail the precise coordination among genetic programs. These programs are driven by the interplay of signaling pathways and transcription factors, which progressively dictate how each tissue should evolve. Here, we discuss the contribution of the Hh, Wnt, FGF, and BMP signaling pathways to the early patterning of the retina. Comparative studies in different vertebrate species have shown that their morphogenetic activity is repetitively used to orchestrate the progressive specification of the eye with evolutionary conserved mechanisms that have been adapted to match the specific need of a given species.

Suppression of cone-driven responses by rods in the isolated frog retina

1988 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
Cun-Jian Dong ◽  
Hao-Hua Qian ◽  
John S. McReynolds ◽  
Xiong-Li Yang ◽  
Yu-Min Liu
Keyword(s):  
Dark Adaptation ◽  
Visual Pigment ◽  
Pigment Epithelium ◽  
Signal Transmission ◽  
Receptor Potential ◽  
Response Sensitivity ◽  
Long Wavelength ◽  
Negligible Amount ◽  
Frog Retina ◽  
Time Courses

AbstractThe sensitivity of rod- and cone-driven responses was studied in the isolated frog retina during the period of rapid dark adaptation following a conditioning flash which bleached a negligible amount of visual pigment. Following a conditioning flash, cone-driven b-wave responses were first enhanced and then depressed. The time courses of the enhancement and subsequent depression of cone-drive responses varies greatly with the intensity and wavelength of the conditioning flash, but were identical when the conditioning' flashes were matched for equal excitation of 502 nm rods. These changes in cone-driven response sensitivity were correlated with the desensitization and recovery of rods following the conditioning flash. When signal transmission from rods to second-order cells was interrupted by the addition of L-glutamate, the conditioning flash did not produce the above-described enhancement and subsequent depression of long-wavelength receptor potential responses. The suppression of cone-driven response therefore appears to be due to a synaptically mediated influence from 502 nm rods which is maximal when the rods are in the dark-adapted state, with little or no contribution from 433 nm rods, and no involvement of the pigment epithelium.

Catecholaminergic binding sites in cat retina, pigment epithelium and choroid

1986 ◽  
Vol 43 (2) ◽  
pp. 147-151 ◽  
Author(s):  
A. Bruinink ◽  
S. Dawis ◽  
G. Niemeyer ◽  
W. Lichtensteiger
Keyword(s):  
Binding Sites ◽  
Pigment Epithelium ◽  
Cat Retina ◽  
Retina Pigment Epithelium

An unusual structural organization to the gut of a digenetic trematode, Fellodistomum fellis

Parasitology ◽  
1982 ◽  
Vol 85 (1) ◽  
pp. 53-60 ◽  
Author(s):  
D. W. Halton
Keyword(s):  
Cell Surface ◽  
Elemental Analysis ◽  
Structural Organization ◽  
Digenetic Trematode ◽  
Blood Components ◽  
Ultrastructural Examination ◽  
Anterior Portion ◽  
Digestive Cells ◽  
Histochemical Tests ◽  
Host Blood

SUMMARYAn ultrastructural examination of Fellodistomum fellis has revealed that the caecal lining consists of 2 distinct components: (a) cup-shaped digestive cells and (b) a pleomorphic layer of cytoplasm which supports and separates individual digestive cells. The digestive cells sequester host blood components within apical pockets formed by lamellated extensions of the cell surface, and undergo asynchronous, cyclical transformations in morphology associated with extracellular digestion and with the extrusion to the gut lumen of pigmented digestive residues. Histochemical tests and elemental analysis of the pigment suggest that it is a ferripor-phyrin, haematin. In the anterior portion of the caecum the supporting cytoplasmic layer is in continuity with the oesophageal tegument and snares the same ultrastructure. It is concluded that the digestive cells are supported by an extension of the foregut tegument.

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