Studies on the Cornea

Kaye, Gordon I.; Pappas, George D.; Donn, Anthony; Mallett, Nancy M.

doi:10.1083/jcb.12.3.481

Cited by 77 publications

(13 citation statements)

References 16 publications

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“…Similarly the wall of the capillaries in the cerebral cortex, although continuous, becomes thinner as the animal progresses to the adult stage (19). In recent studies (20,21) marker particles were found to traverse the corneal endothelium (Descemet's mesothelium) by an intercellular pathway. In this area, the particles appear to be streaming out of the intercellular space where they fan out into Descemet's membrane.…”

Section: Figures 9 and I0mentioning

confidence: 99%

An Electron Microscopic Study of the Passage of Colloidal Particles From the Blood Vessels of the Ciliary Processes and Choroid Plexus of the Rabbit

Pappas

Tennyson

1962

The Journal of Cell Biology

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104

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The thinnest areas of the capillaries of the choroid plexus and ciliary processes in the eye of the rabbit are characterized by the presence of fenestrae. When various colloidal particles opaque to the electron beam (thorotrast, gold sol, and saccharated iron oxide) were injected into the blood stream, none were found in fenestrae or in areas that might suggest their having passed through fenestrae. The passage of marker particles from the lumen to the surrounding connective tissue does take place on occasion in the areas of thicker walls in the capillaries and venules rather than in the attenuated and fenestrated endothelial walls. The pathway taken by these markers may be either through the cytoplasm of the endothelial cells via membrane-bounded vesicles and vacuoles or through the intercellular spaces of the vessels. An altered aqueous humor (cloudy and plasmoid) was produced by endotoxin injection or by making a draining fistula in rabbit cornea. Both methods gave rise to the same changes in the blood vessels of the ciliary processes. Under such conditions of inflammation the passage of colloidal particles through the thicker walls of the capillaries and venules was greatly increased and occurred primarily as an intercellular passage between the endothelial cells. The attenuated and fenestrated areas of the endothelium of the small capillaries remained unchanged with no particles passing through them. These results on the altered vessels of the ciliary processes parallel those of Majno and Palade (26) on the rat cremaster muscle.

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Section: Figures 9 and I0mentioning

confidence: 99%

An Electron Microscopic Study of the Passage of Colloidal Particles From the Blood Vessels of the Ciliary Processes and Choroid Plexus of the Rabbit

Pappas

Tennyson

1962

The Journal of Cell Biology

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104

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“…T h e particles appear to have been liberated at this surface by the fusion of the vesicular m e m b r a n e with the apical cell membrane and the subsequent release of the contents of the vesicle. This would represent an inversion of the process of pinocytosis in which particles are internalized into vesicles at the apical surface when they have been placed in contact with that surface by injection into the anterior chamber, or by in vitro techniques (43). Fig.…”

Section: The Uptake and Transport Of Colloidal Particles By The Cornementioning

confidence: 99%

“…This may be due partly to the fact that the clumping reduces the n u m b e r concentration of particles which diffused as far as the basement m e m b r a n e of the epithelium was too low to permit any conclusions as to whether these particles would pass through this structure. In vitro observations on the diffusion of particles through the stroma (43) indicate that the basement m e m b r a n e of the epithelium may be a barrier across which the particles do not pass readily.…”

Section: Fmvre 10mentioning

confidence: 99%

“…12 and 13). A proposed mechanism for the circumventing of the terminal bar during the transport of colloidal particles into the cornea by the rabbit corneal endothelium is presented in another communication (43).…”

Section: Figure 15mentioning

confidence: 99%

“…It has been observed in in vitro studies (43) carried out in the chamber of Donn, Maurice, and Mills (23) that ThO2 rapidly settles out of the perfusing fluid after injection. In in vitro experiments, therefore, the clamp was always placed so that the surface being exposed to the test solution was essentially horizontal.…”

Section: Figure 15mentioning

confidence: 99%

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Studies on the Cornea

Kaye

Pappas

1962

The Journal of Cell Biology

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165

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Physiological studies have demonstrated that ions, as well as large molecules such as hemoglobin or fluorescein, can diffuse across and within the cornea. Most of the substrates for corneal metabolism are obtained from aqueous humor filling the anterior chamber. In order to receive its nutrients and in order to maintain its normal conditions of hydration, the avascular cornea must transport relatively large amounts of solute and solvent across the cellular layers which cover this structure. It has been suggested in the past that there may be a morphological basis for the transport of large amounts of solvents and solutes by cells by the mechanism of pinocytosis. The use of electron-opaque markers to study fluid movements at the electron microscope magnification level was described by Wissig (29). The present study describes the fine structure of the normal rabbit cornea and the pathways of transport of colloidal particles by the cornea in vivo. Rabbit corneas were exposed in vivo to suspensions of saccharated iron oxide, thorium dioxide, or ferritin by injection of the material into the anterior chamber. In other experiments thorium dioxide or saccharated iron oxide was injected into the corneal stroma, producing a small bleb. Particles presented at the aqueous humor surface of the rabbit corneal endothelium are first attached to the cell surface and then pinocytosed. It appears that the particles are carried around the terminal bar by an intracellular pathway involving the pinocytosis of the particles and their subsequent transport in vesicles to the lateral cell margin basal to the terminal bar. Particles introduced at the basal surface of the endothelium (via blebs in the corneal stroma) are apparently carried through the endothelial cells in membrane-bounded vesicles without appearing in the intercellular space. There appears to be free diffusion of these particles through Descemet's membrane and the corneal stroma. The stromal cells take up large quantities of the particles when blebs are injected into the stroma.

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Cornea and Sclera

Dohlman¹

1964

Archives of Ophthalmology

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Studies on the Cornea

Cited by 77 publications

References 16 publications

An Electron Microscopic Study of the Passage of Colloidal Particles From the Blood Vessels of the Ciliary Processes and Choroid Plexus of the Rabbit

An Electron Microscopic Study of the Passage of Colloidal Particles From the Blood Vessels of the Ciliary Processes and Choroid Plexus of the Rabbit

Studies on the Cornea

Cornea and Sclera

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