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Electron microscopic observations on degeneration in the pigment epithelium of the human retina
ABSTRACTS
177
El% 4 11as abolished 2-7 min after intravenous injection whereas after int’ravitreous injection alterat,ions of ERG reached their maximum only 15-20 min after the injection, without. ever leading t,o a complete extinction of retinal activity. This diflerence of behaviour may be explained hv a faster raise of the iodoacetic acid concentration in the outer retinal layers after iutravenous injections. illterations of ERG showed up in a characteristic temporal order: a fast diminution of b-have amplitude preceding charges of a-wave, oscillary potentials and temporal parameters. The first detectable ultrastructural lesions were nresent in &Killer cells which showed distended and part,ly disrupted endoplasmic reticulum, interpreted as si,ss of altered metabolic activity of the glia. Oedema of optic nerve fibres occurred after intravitreous injection, but this is not implicated in the biogenesis of ERG. No other ultrastructural retinal lesions became evident within 3 h of the injection. The a hove observations lend support to the Jliiller cells being implicated in the biogenesis ot ERG. (Supported by SNSF, grant 3300.70.)
Retinal Glycogen in Relation to BIood Circulation D. KASAJ~L.
0. Hoc:r
U. METZLER
In the rabbit retinal glycogen, interruption of the blood supply
Contributions Retinas
and C. SCHEDLER,
which was to t’he eye.
traced
Bonn
histochemically,
of Rods and Cones to the Electroretinographic
disappears
3045
min
Responses of Isolated
after
Human
Human retinas isolated in daylight respond to intense whim stimuli with photopic electroretinograms (Yickel et al., 1961). In the present study, evidence for a functioning scotopic system was obtained from human retinas dark adapted prior to, and during, the isolation procedure. The retinas were dissected from eyes enucleated because of malignant tumours. Retinal pieces of 0.3 cm* were incubated at 36°C in a glucose-containing ionic medium of pH 7.4. No plasma was added to the perfusate. Electroretinographic responses to monochromatic stimuli were recorded. Scotopic b-waves were obtained in 7 out of 8 retinas. The amount of energy required to elicit a just detectable response corresponded to approximately one quantum absorbed per rod when the stimulus lasted 30 msec. The threshold irradiance of longer stimuli (600 msec) amounted to 4 :; 1OF erg se+ cm-?, is no more than 3.6 log units above the corresponding psychophysical threshold. Similar weak stimuli were sufficient to elicit threshold P III responses in ageing preparations. Scotopic spectral sensitivities were found for both b-wave and P III. After exposure to intense radiation at 503 nm which bleached substantial amounts of rhodopsin, the eleetroretinogram consisted merely of components showing a photopic spectral sensitivity.
Siekel, \V., Lippmann, 63, 316-318.
Electron Microscopic Retina IV. LEIK;HE,
H. G., Haschke,
Observations
REFEREKCE \I-. and Baumann,
on Degeneration
Ch.
(1961).
Ber.
dtsch.
in the Pigment Epithelium
opldhd.
Ues.
of the Human
Hnnaburg
After a short explanation of the normal structure of t.he pigment epithelium of the human eye the author ctescribes the different changes within the cell which should be regarded as degenerative. The morphological changes consist of: (1) different sized vacuoles or cystic cavities which occur singly or in groups, spread out in the cvtoplasm or in the base of the cell. The endoplasmic reticulum shows small vacuoles instead o> tubules in cytoplasm. These vacuoles are found close to each other. (2) (iiant membrane structures which are lined up in terms of a circle or of an arch and at some places chains of vacuoles are to be detected; (3) conglomerations of long ergastoplasmic lamellae with terminal cystic enhancement,s; (4) lamellar systems looking like degenerate outer segments, and consisting of concentric layers of membranes ; (5) round homogenous and electron-dense bodies located in the cell, sometimes in direct contact to I hi: nucleus.
177
El% 4 11as abolished 2-7 min after intravenous injection whereas after int’ravitreous injection alterat,ions of ERG reached their maximum only 15-20 min after the injection, without. ever leading t,o a complete extinction of retinal activity. This diflerence of behaviour may be explained hv a faster raise of the iodoacetic acid concentration in the outer retinal layers after iutravenous injections. illterations of ERG showed up in a characteristic temporal order: a fast diminution of b-have amplitude preceding charges of a-wave, oscillary potentials and temporal parameters. The first detectable ultrastructural lesions were nresent in &Killer cells which showed distended and part,ly disrupted endoplasmic reticulum, interpreted as si,ss of altered metabolic activity of the glia. Oedema of optic nerve fibres occurred after intravitreous injection, but this is not implicated in the biogenesis of ERG. No other ultrastructural retinal lesions became evident within 3 h of the injection. The a hove observations lend support to the Jliiller cells being implicated in the biogenesis ot ERG. (Supported by SNSF, grant 3300.70.)
Retinal Glycogen in Relation to BIood Circulation D. KASAJ~L.
0. Hoc:r
U. METZLER
In the rabbit retinal glycogen, interruption of the blood supply
Contributions Retinas
and C. SCHEDLER,
which was to t’he eye.
traced
Bonn
histochemically,
of Rods and Cones to the Electroretinographic
disappears
3045
min
Responses of Isolated
after
Human
Human retinas isolated in daylight respond to intense whim stimuli with photopic electroretinograms (Yickel et al., 1961). In the present study, evidence for a functioning scotopic system was obtained from human retinas dark adapted prior to, and during, the isolation procedure. The retinas were dissected from eyes enucleated because of malignant tumours. Retinal pieces of 0.3 cm* were incubated at 36°C in a glucose-containing ionic medium of pH 7.4. No plasma was added to the perfusate. Electroretinographic responses to monochromatic stimuli were recorded. Scotopic b-waves were obtained in 7 out of 8 retinas. The amount of energy required to elicit a just detectable response corresponded to approximately one quantum absorbed per rod when the stimulus lasted 30 msec. The threshold irradiance of longer stimuli (600 msec) amounted to 4 :; 1OF erg se+ cm-?, is no more than 3.6 log units above the corresponding psychophysical threshold. Similar weak stimuli were sufficient to elicit threshold P III responses in ageing preparations. Scotopic spectral sensitivities were found for both b-wave and P III. After exposure to intense radiation at 503 nm which bleached substantial amounts of rhodopsin, the eleetroretinogram consisted merely of components showing a photopic spectral sensitivity.
Siekel, \V., Lippmann, 63, 316-318.
Electron Microscopic Retina IV. LEIK;HE,
H. G., Haschke,
Observations
REFEREKCE \I-. and Baumann,
on Degeneration
Ch.
(1961).
Ber.
dtsch.
in the Pigment Epithelium
opldhd.
Ues.
of the Human
Hnnaburg
After a short explanation of the normal structure of t.he pigment epithelium of the human eye the author ctescribes the different changes within the cell which should be regarded as degenerative. The morphological changes consist of: (1) different sized vacuoles or cystic cavities which occur singly or in groups, spread out in the cvtoplasm or in the base of the cell. The endoplasmic reticulum shows small vacuoles instead o> tubules in cytoplasm. These vacuoles are found close to each other. (2) (iiant membrane structures which are lined up in terms of a circle or of an arch and at some places chains of vacuoles are to be detected; (3) conglomerations of long ergastoplasmic lamellae with terminal cystic enhancement,s; (4) lamellar systems looking like degenerate outer segments, and consisting of concentric layers of membranes ; (5) round homogenous and electron-dense bodies located in the cell, sometimes in direct contact to I hi: nucleus.