Freeze-fracture observations of pigment epithelial cells of the frog retina

Hirosawa, Kazushige

doi:10.1016/0014-4835(79)90082-4

Cited by 6 publications

(1 citation statement)

References 32 publications

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“…The alteration of the lipidic composition of the SER leads to the formation of MBs in the pigment epithelial cell. 10,18,19) In the present study, we found that the MB of the frog RPE appeared as the lenticular, crescentic, circular and spherical forms. The center of the circular MB contained some tubular SER, while the lamellae in the spherical form were compactly arranged along a concentric axis in the central region.…”

Section: Discussionsupporting

confidence: 53%

Three-dimensional Structure of Myeloid Bodies in the Retinal Pigment Epithelium of the Frog, Rana pipiens

Liu

Hatae

Ichimura

et al. 1996

Okajimas Folia Anatomica Japonica

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The three-dimensional structures of myeloid bodies (MBs) in the retinal pigment epithelium (RPE) of the frog (Rana pipiens) were studied by transmission and scanning electron microscopy. MBs were observed to be an assemblies of numerous membranous lamellae that were formed by a flattened saccule of the paired membranes in the RPE. On thin-section, they appeared as lenticular, crescentic, circular and spherical forms and were associated with adjacent smooth endoplasmic reticulum (SER) and nuclear membranes. The lenticular MBs were observed to be in connection with the crescentic, circular and spherical forms. Under scanning electron microscopy, the lenticular and crescentic MBs showed a pile of disc-liked lamellae, while the circular and spherical MBs displayed an onion-liked appearance. It was noted that some tubular SER remained in the center of the circular MBs, while the lamellae were compactly arranged and filled the central region in the spherical MBs. All crescentic and spherical MBs were continuous with the lenticular and crescentic MBs. These results suggest that the lenticular MBs may be a precursor form of another variety of MBs which may be transformed into the crescentic, circular and spherical forms by the curving and fusion of the lamellar membranes at the MB's free ends.

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Section: Discussionsupporting

confidence: 53%

Three-dimensional Structure of Myeloid Bodies in the Retinal Pigment Epithelium of the Frog, Rana pipiens

Liu

Hatae

Ichimura

et al. 1996

Okajimas Folia Anatomica Japonica

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Freeze‐fracture study of photoreceptor outer segments and pigment epithelium in dystrophic and normal retinas

McLaughlin

Boykins

1981

J of Comparative Neurology

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The intramembrane organization of outer segment (OS) membranes and pigment epithelial (PE) microvilli has been studied in rats (10-17 postnatal days) with inherited retinal degeneration (RCS) and in normal retinas from genetically controlled rats (RCS-rdy+). The OS plasma membranes of both dystrophic and normal retinas are characterized by large particles surrounding circular, particle-free zones on the P-faces (cytoplasmic leaflets) and a sparse distribution of particles on the E-faces (external leaflets). No regional differences in particle distribution are observed in either basal or distal plasma membrane regions. Outer segment disc membranes are characterized by large, densely packed P-face particles and ridged E-faces with very few particles. Small, particle-free patches of membrane are present in the basal disc P-faces of both normal and dystrophic retinas, which Andrews and Cohen ("79) have described as characteristic of newly added disc membrane. In dystrophic retinas, larger, particle-free domains are observed in the distal disc membranes (P-faces) and accumulating membranous debris. In older retinas, which have accumulated more debris, the particle-free domains occupy vast areas of the membrane faces and it is not possible to identify these membranes as belonging to either discs of plasma membranes. No comparable areas of particle-free membrane are observed in the distal discs and OS plasma membranes of normal retinas. Pigment epithelial microvillus membranes are characterized by an intermixture of large and medium-sized particles surrounding irregular particle-free areas, but no differences between normal and dystrophic PE membranes are observed. The changes in particle distribution observed in the dystrophic retinas suggests that the intramembrane molecular composition of older disc membranes has become altered or rearranged as the OS membranes accumulate as debris.

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Lectin cytochemistry and freeze‐fracture study of phagocytosis in the rat retina

McLaughlin

Boykins

1984

J of Comparative Neurology

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Lectin cytochemistry and freeze-fracture intramembrane morphology have been studied in adult rat retinas during various stages of the phagocytic cycle. Animals were perfused with aldehydes at various times during the first 6 hours of light and the retinas were removed. Chopped sections of tissue were stained with one of two lectin-peroxidase conjugates: ricinis communis agglutinin (RCA), which is specific for n-acetylgalactosamine and galactose, or wheat germ agglutinin (WGA), which is specific for n-acetylglucosamine and sialic acid. Other sections were frozen and prepared for freeze fracture. During the first hour of light onset, numerous phagosomes are already present in the retinal pigment epithelial (RPE) cytoplasm. The engulfment stages of phagocytosis whereby the RPE microvilli wrap around and enclose shed rod outer segment (ROS) tips are rarely observed at this time. Newly formed phagosomes are present in the apical RPE cytoplasm while older and more osmiophilic phagosomes are located deeper within the RPE cytoplasm. Between 2 and 4 hours of light onset fewer phagosomes are present in the RPE cytoplasm, but it is common to observe many ROS tips in various stages of microvillous engulfment. By 6 hours phagosomes are rarely present but some engulfed ROS tips continue to be observed. Both RCA and WGA stain RPE microvilli and plasma membranes of photoreceptor outer segments. WGA, in addition, labels some intradisc membranes of intact and also shed outer segments that are being engulfed but does not label disc membranes in phagosomes. At all times, phagosomes are rimmed by both lectin stains, but their internal contents are never stained. Lysosomes and multivesicular and residual bodies are labeled by both lectins. Freeze-fractured retinas show that as the ROS tips are engulfed, particle-free areas are present on disc P-face (cytoplasmic) membranes. Many newly formed phagosomes also display particle-free membrane areas and older phagosome membranes are completely devoid of particles. These observations show that the changes in WGA staining and intramembrane particle distribution on disc membranes occur in retinas during phagocytosis and suggest that some membrane component that is present for the initial phagocytic interaction may be rapidly degraded thereafter.

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Freeze-fracture observations of pigment epithelial cells of the frog retina

Cited by 6 publications

References 32 publications

Three-dimensional Structure of Myeloid Bodies in the Retinal Pigment Epithelium of the Frog, Rana pipiens

Three-dimensional Structure of Myeloid Bodies in the Retinal Pigment Epithelium of the Frog, Rana pipiens

Freeze‐fracture study of photoreceptor outer segments and pigment epithelium in dystrophic and normal retinas

Lectin cytochemistry and freeze‐fracture study of phagocytosis in the rat retina

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