Nonpigmented Epithelium Research Articles

Barium and K+ on surface and tubular cell resistances of frog stomach with microelectrodes

ARTICLESBarium and K+ on surface and tubular cell resistances of frog stomach with microelectrodesJ O'Callaghan, SS Sanders, RL Shoemaker, and WS RehmJ O'Callaghan, SS Sanders, RL Shoemaker, and WS RehmPublished Online:01 Aug 1974https://doi.org/10.1152/ajplegacy.1974.227.2.273MoreSectionsPDF (4 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByRegulation of Cardiac Afferent Excitability in Ischemia10 June 2009Electrophysiology of Gastric Ion Transport1 January 2011Mechanically stripped pigmented and non-pigmented epithelium of the shark ciliary body: Morphology and transepithelial electrical propertiesExperimental Eye Research, Vol. 49, No. 6Transport properties of the basolateral membrane of the oxyntic cells in frog fundic gastric mucosaPfl�gers Archiv European Journal of Physiology, Vol. 414, No. 4Inhibition of acid secretion of fundus of Rana pipiens with a high concentration of potassium on the secretory sideBiochimica et Biophysica Acta (BBA) - Biomembranes, Vol. 899, No. 1Ion Transport by Gastric MucosaMicroelectrode study of effects of luminal K+ on surface cells of frog stomachBiochimica et Biophysica Acta (BBA) - Biomembranes, Vol. 856, No. 3Ion Transport by Gastric MucosaEffects of forskolin, prostaglandin F2α, and Ba2± on the short-circuit current of the isolated rabbit iris-ciliary body2 July 2009 | Current Eye Research, Vol. 5, No. 7Impedance analysis in epithelia and the problem of gastric acid secretionThe Journal of Membrane Biology, Vol. 72, No. 1-2Structure of oxyntic cell membranes during conditions of rest and secretion of HCl as revealed by freeze-fractureThe Anatomical Record, Vol. 196, No. 2Relative roles of Ca2+, Sr2+, Ba2+ and Mg2+ in controlling lens permeability characteristicsCell Calcium, Vol. 1, No. 1Gastric SecretionIon and Water Transport in Gastric MucosaElectrical Events During Activation and Inhibition of Gastric HCI SecretionGastroenterology, Vol. 73, No. 4Ultrastructural and Physiological Changes in Piglet Oxyntic Cells During Histamine Stimulation and Metabolic InhibitionGastroenterology, Vol. 69, No. 6IMPLICATIONS OF THE NEUTRAL CARRIER Cl − -HCO 3− EXCHANGE MECHANISM IN GASTRIC MUCOSA fn116 December 2006 | Annals of the New York Academy of Sciences, Vol. 264, No. 1Ion Transport and Short-Circuit Technique More from this issue > Volume 227Issue 2August 1974Pages 273-288 Copyright & PermissionsCopyright © 1974 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1974.227.2.273PubMed4546735History Published online 1 August 1974 Published in print 1 August 1974 Metrics

Selective Destruction of the Pigmented Epithelium in the Ciliary Body of the Eye

Perfusion of the internal carotid artery with hypertonic solution selectively destroys most of the pigmented epithelium of the ciliary body of the monkey eye, converts fenestrated endothelium of capillaries to continuous endothelium, and transiently breaks down the blood-aqueous barrier. The nonpigmented epithelium regenerates and the intraocular pressure returns to normal even though the pigmented epithelium is permanently destroyed.

Histochemical interpretation of fluorescein angiogram. II. Background fluorescence and macular dark spot.

The characteristics of the localization of fluorescein in the iris, ciliary body and retina were studied in the monkey eye by the whole mount preparation and paraffin section methods. By incident light fluorescence microscopy and transparent fluorescence microscopy the penetration of free fluorescein into the outer retinal layer as well as into of the nonpigmented epithelium of the ciliary body is noted. The site of the permeability barrier for protein-bound fluorescein is postulated in the pigment epithelium and the ciliary epithelium. From the anatomical and embryological points of view, the two kinds of epithelium may have the same tendency as to the permeability of fluorescein.

The electrolyte content, osmolarity and site of secretion of the aqueous humor in two teleost fishes ( Carassius auratus and Diplodus sargus)

The sodium, and chloride concentrations, and total osmolarity in the aqueous humor were found to be significantly lower than in the plasma of two teleosts, namely the fresh water Carassius auratus and the marine Diplodus sargus. This gradient of concentration was broken down by repeated paracentesis, and by injection of 10 −4 m ouabain in the anterior chamber. Increased sodium chloride in the plasma of Carassius, adapted to higher salinity in the external water, induced increases of sodium and chloride in the aqueous. The gradient of concentration was well maintained for sodium and potassium but not for chloride. Out-flow curves of labelled sodium from the anterior chamber were measured by external counting in the flounder ( Platichthys flesus). It is concluded that sodium reabsorption from the aqueous is involved in the mechanism of formation of this fluid in these fish. The site of secretion of the aqueous in Carassius and Sargus most probably is located at the root of the iris in the posterior non-pigmented epithelium. Electronmicrographs of this portion show microvilli, infoldings and sacs of the endoplasmic reticulum as well as a great number of mitochondria. In contrast, the posterior epithelium of the pupillary portion of the iris has a flat posterior cellular membrane and numerous pigment granules without secretory characteristics.

Aqueous humor formation in fish: The role of sodium-potassium-activated adenosine triphosphatase in the spiny dogfish ( Squalus acanthias) eye

The anatomy of the fish ciliary body and the distribution of sodium-potassium-activated adenosine triphosphatase in the elasmobranch ( Squalus acanthias) eye were studied in an attempt to localize the site of formation of aqueous humor. Both teleosts and elasmobranchs have a ciliary body with a nonpigmented and pigmented epithelium similar to the mammalian pars plana. The fish ciliary body has no processes and little or no smooth muscle. Sodium-potassium-activated adenosine triphosphatase was found in significant levels in the elasmobranch retina, ciliary body and brain, while the iris had little activity. If the elasmobranch eye is similar to the mammalian eye and sodium transport is involved in aqueous humor formation, the ciliary body seems the most likely site of transport.

The blood-aqueous barrier to tracer protein: a light and electron microscopic study of the primate ciliary process

Combined light and electron microscopic examination of the normal monkey ciliary process revealed that continuous belts of zonulae occludentes junctions are located in the lateral intercellular spaces of the nonpigmented epithelium near the apical surface. Following systemic peroxidase injection, this tracer protein is observed to penetrate the ciliary process blood vessel walls and perivascular stroma. The movement of the tracer is impaired partially in the pigmented epithelium by a series of interspersed zonular and macular junctions. The tracer is observed to enter the lateral intercellular spaces of the nonpigmented epithelium but its passage through the nonpigmented layer is prevented by the zonulae occludentes (“tight”) junctions which effectively seal off these interspaces to peroxidase. No evidence for the vesicular transport of peroxidase across the nonpigmented epithelium was found. It is suggested that these “tight” junctions represent the site of a blood-aqueous barrier to large molecules.

Carbonic anhydrase in the developing ciliary processes of the rabbit eye

Carbonic anhydrase activity in the developing ciliary processes of rabbit eyes has been investigated by a histochemical method. The non-pigmented epithelium of the ciliary processes of the foetus shows no enzyme activity although this is present in other ocular tissues. Soon after birth, carbonic anhydrase appears in the non-pigmented epithelium and reaches the adult level in about 4 weeks. It is suggested that this appearance of carbonic anhydrase coincides with the onset of the formation of aqueous humour in rabbits, and that aqueous formation is dependent on carbonic anhydrase in this species.

Behavior of Retinal Pigment Epithelium in Organ Culture Conditions

In organ culture conditions the retinal pigment epithelium of the chick embryo presents two patterns of growth: (1) it covers the choroidal and scleral mesoderm, and (2) it invaginates into it forming glandular structures. In each case the retinal pigment epithelium cells may keep or loose their pigment. Occasionally they are transformed into a nonpigmented stratified epithelium. The retinal pigment epithelium cells keep their pigment only when the contact with Bruch’s membrane is maintained.

Distribution of carbonic anhydrase in the rabbit eye as demonstrated histochemically

Carbonic anhydrase activity in the ocular tissues of albino rabbits has been demonstrated histochemically. Ciliary and iris epithelium, lens fibres, pigment epithelium, inner segments of rods and cones, outer and inner plexiform layers of retina showed carbonic anhydrase activity. Pigment epithelium of retina and non-pigmented epithelium of ciliary processes contain very high enzyme activity. Acetazolamide in vitro and in vivo inhibited carbonic anhydrase as shown by the absence of staining in the areas with enzyme activity.

Spontaneous nonpigmented iris cysts.

EPITHELIAL cysts arising spontaneously in the iris are classified in two groups—intra-epithelial and stromal.¹The intra-epithelial cysts are made up of pigmented epithelium, and they are regarded as remnants of von Szily's marginal sinus of the iris that have not been obliterated.^2-3 The stromal cysts are situated within the iris stroma and are lined by nonpigmented epithelium. The latter may be multilayered and may contain goblet cells. The origin of these cysts is still controversial.^2-5Some observers hold the opinion that they arise from the surface ectoderm displaced, probably, at the time of formation of the lens vesicle.^6-8Others^9-12believe that they develop from aberrant cells from the most anterior portion of the optic vesicle whiel it is still unpigmented. The histopathologic features of such cysts excised by iridectomy have been illustrated repeatedly,^{1,7-9, 13-18}but we have found only one report describing such

Aqueous humour formation

The effects of a number of metabolic inhibitors on aqueous formation in rabbits are described: These are discussed in the light of experimental findings and explanatory hypotheses about the process of aqueous humour formation which are briefly reviewed. The evidence for active sodium transport is examined and it is shown that support for this hypothesis may arise from experiments using isolated ciliary epithelial tissue in vitro. Aqueous formation is inhibited by fluoroacetate, dinitrophenol and ouabain whilst the composition of the aqueous undergoes little change. The composition may, however, readily by changed by alterations of plasma osmolarity, and it is suggested that the rate of secretion depends upon: Active Na transport is oxygen dependent and subject to inhibition by citrate cycle inhibitors such as malonate and fluoroacetate and by ouabain which inhibits Na+ - K+ - Mg-activated ATP-ase. Histochemical and biochemical studies on ciliary epithelium suggest that the enzymes succinate dehydrogenase, Na-K-Mg-activated ATP-ase and cytochrome oxidase occur predominantly in the non-pigmented cell layer of the epithelium. It is postulated that the systems: citrate cycle, oxidative phosphorylation, ATP synthesis furnish the substrate for Na-K-Mg-activated ATP-ase which is responsible for extruding sodium from the epithelial cell into the posterior chamber. This system appears co-terminous with the non-pigmented epithelium. Glycolysis rates in ciliary epithelium are high, but are not efficient as sources of energy for Na transport. The histochemistry suggests that glycolysis may be associated particularly with the ciliary pigment epithelium. The effects on aqueous secretion of a number of other substances (aldosterone antagonists, agents with selective toxicity to retinal pigment epithelium) are described and discussed, and a conjectural account is given of the metabolism of the ciliary epithelium. In the final section an hypothesis is advanced which attempts to take account of the role of the ciliary pigment epithelium in aqueous production. It is thought that this layer may function as an electrically charged membrane, the charge being maintained from cell metabolism and acting as a ‘permselective filter’ influencing the final result of the active ‘Na-pump’ in the non-pigmented cell layer. In an appendix a description is given of a procedure used to determine the surface area of the ciliary epithelium in rabbits.

The ultrastructure of the capillaries in the ciliary body.

Introduction During the analysis of the fine structure of the ciliary epithelium (Holmberg, 1957; Holmberg, 1959) in human and rabbit eyes, it was observed that the capillaries in the stroma are built up in a characteristic way, similar to that found in several secretory glands. Although the findings are not unique for the ciliary body, they add to our knowledge of the correlation between structure and function of the ciliary processes. Material and Methods In this investigation the same rabbit material has been utilized as was used for the analysis of the nonpigmented epithelium. All fixation was performed in vivo in 1% osmium solution with the animals under general anesthesia (pentobarbital [Nembutal] intravenously). After 10-15 minutes parts of the ciliary body were cut out and fixation was continued for 3-4 hours. The human material consists of three fresh eyes enucleated because of malignant melanoma in the posterior pole. Immediately after

Differences in ultrastucture of normal human and rabbit ciliary epithelium.

Introduction In a previous investigation (Holmberg, 1957), an extensive analysis of the ultrastructure of the nonpigmented epithelium in rabbit eyes was carried out. The material included both the normal structure and changes in the structure after inhibition of the secretion of aqueous humor by acetazolamide (Diamox). In order to find out the effect of acetazolamide on the structure of human ciliary epithelium, an analysis of the normal ultrastructure of this epithelium has been started. As there proved to be remarkable differences as compared to the rabbit material, a preliminary report of these differences seems to be justified. Material and Methods So far three enucleated human eyes have been examined. The eyes were enucleated because of a malignant melanoma in the posterior pole. No clinical signs of altered secretion of aqueous humor could be detected. The operations were performed under local anesthesia (retrobulbar injection of Xylocaine). Immediately after the enucleation 1%

STUDIES OF THE ULTRASTRUCTURE OF THE NON‐PIGMENTED EPITHELIUM IN THE CILIARY BODY

Acta OphthalmologicaVolume 33, Issue 4 p. 377-381 STUDIES OF THE ULTRASTRUCTURE OF THE NON-PIGMENTED EPITHELIUM IN THE CILIARY BODY Åke Holmberg, Åke Holmberg Department of Histology, Karolinska Institutet. (Head: Prof. G. Häggqvist M.D.) and The Eye Department, Sabbatsbergs Sjukhus (Head: I. Kugelrerg M.D.) Stockholm, Sweden Received Dec. 23rd 1954.Search for more papers by this author Åke Holmberg, Åke Holmberg Department of Histology, Karolinska Institutet. (Head: Prof. G. Häggqvist M.D.) and The Eye Department, Sabbatsbergs Sjukhus (Head: I. Kugelrerg M.D.) Stockholm, Sweden Received Dec. 23rd 1954.Search for more papers by this author First published: August 1955 https://doi.org/10.1111/j.1755-3768.1955.tb00075.xCitations: 11 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume33, Issue4August 1955Pages 377-381 RelatedInformation

Function of the Columnar Epithelium of the Ciliary Body of Albino Rabbits.

The assumption of secretory function of the non-pigmented epithelium of the ciliary body (Leber,1 Seidel2) has not been satisfactorily confirmed. Some clinical experience of quick absorption of vitreous hemorrhages, however, seems to point to a possible absorbing function; and Meller3 was able to show blood pigments in the inner layer of ciliary epithelium in such a case. Experiments were therefore attempted on albino rabbits to investigate this question.The ciliary body of the rabbit is covered by an inner and an outer layer of epithelium. The inner epithelial cells are not uniform, some being columnar, others cubic or flat, while those of the outer layer are uniformly cubic. Each of the columnar cells, which are concerned in this study, is limited sidewise by a very thin membrane and outwardly by a definite thick membrane closely similar to the cuticular membrane of the intestinal columnar cells. Further, the intracellular arrangement of mitochondria and Golgi apparatus is identical to that of the intes...