Vitreous humor of chicken contains two fibrillar systems: An analysis of their structure

doi:10.1016/0889-1605(88)90039-0

Journal of Ultrastructure and Molecular Structure Research

Volume 100, Issue 3, September 1988, Pages 224-234

Journal of Ultrastru...

https://doi.org/10.1016/0889-1605(88)90039-0 Get rights and content

Abstract

An analysis of the structure of chicken vitreous humor after brief homogenization of the tissue was performed. Electron micrographs prepared after rotary shadowing with platinum showed the presence of two distinct fibrils. The collagen fibril was coated by glycosaminoglycan which could be removed by chondroitinase ABC digestion. In addition, individual molecules of tenascin were observed wrapped around some of the collagen fibrils. A second beaded fibril was present and several fine filaments were observed to extend from each bead. The beaded fibril is formed by the overlap of these filaments, and beaded fibrils were observed in either a “closed” or an “open” form dependent on whether all of the filaments are brought together to form the overlap. A schematic diagram is presented for the structure of the beaded fibril. The potential relationship of the beaded fibril to the zonular fibrils and the elastin microfibrils is briefly discussed.

References (51)

W.G. Carter
J. Biol. Chem
(1982)
R. Chiquet-Ehrismann et al.
Cell
(1986)
R. Chiquet-Ehrismann et al.
Cell
(1988)
B. Dublet et al.
J. Biol. Chem
(1987)
J. Engel et al.
J. Mol. Biol
(1981)
D.R. Eyre et al.
FEBS Lett
(1987)
A. Faissner et al.
Differentiation
(1988)
J. Fitch et al.
Dev. Biol
(1988)
S. Goldfischer et al.
Tissue Cell
(1985)
M.H. Irwin et al.
J. Biol. Chem
(1986)

R.P. Mecham et al.

Biochem. Biophys. Res. Commun

(1988)

B.R. Olsen

J. Ultrastruct. Res

(1965)

T.M. Schmid et al.

J. Ultrastruct. Res

(1984)

G.N. Smith et al.

Dev. Biol

(1978)

R.L. Trelstad et al.

Exp. Eye Res

(1974)

M. Van der Rest et al.

J. Biol. Chem

(1988)

K.G. Vogel et al.

Biochem. Biophys. Res. Commun

(1987)

S. Ayad et al.

Biochem. J

(1984)

E.A. Balazs et al.

Exp. Eye Res

(1965)

M.A. Bourdon et al.

Cancer Res

(1983)

M.A. Bourdon et al.

J. Cell Biol

(1987)

R.R. Bruns

J. Ultrastruct. Res

(1984)

M. Chiquet et al.

J. Cell Biol

(1984)

E.G. Cleary

H.P. Erickson et al.

J. Cell Biol

(1987)

Cited by (101)

Characterization of the development of the high-acuity area of the chick retina
2024, Developmental Biology
The fovea is a small region within the central retina that is responsible for our high acuity daylight vision. Chickens also have a high acuity area (HAA), and are one of the few species that enables studies of the mechanisms of HAA development, due to accessible embryonic tissue and methods to readily perturb gene expression. To enable such studies, we characterized the development of the chick HAA using single molecule fluorescent in situ hybridization (smFISH), along with more classical methods. We found that Fgf8 provides a molecular marker for the HAA throughout development and into adult stages, allowing studies of the cellular composition of this area over time. The radial dimension of the ganglion cell layer (GCL) was seen to be the greatest at the HAA throughout development, beginning during the period of neurogenesis, suggesting that genesis, rather than cell death, creates a higher level of retinal ganglion cells (RGCs) in this area. In contrast, the HAA acquired its characteristic high density of cone photoreceptors post-hatching, which is well after the period of neurogenesis. We also confirmed that rod photoreceptors are not present in the HAA. Analyses of cell death in the developing photoreceptor layer, where rods would reside, did not show apoptotic cells, suggesting that lack of genesis, rather than death, created the “rod-free zone” (RFZ). Quantification of each cone photoreceptor subtype showed an ordered mosaic of most cone subtypes. The changes in cellular densities and cell subtypes between the developing and mature HAA provide some answers to the overarching strategy used by the retina to create this area and provide a framework for future studies of the mechanisms underlying its formation.
Genetics of Canine Primary Glaucomas
2015, Veterinary Clinics of North America - Small Animal Practice
Remodelling of the human vitreous and vitreoretinal interface - A dynamic process
2010, Progress in Retinal and Eye Research
Citation Excerpt :
It consists of just 0.1% macromolecules (Hogan et al., 1971b). The most important macromolecules (see Biochemistry of the vitreous) are the collagens (Swann, 1980; Bishop et al., 1994a; Ayad and Weiss, 1984; Mayne et al., 1991; Seery and Davison, 1991; Bishop et al., 1991; Brewton et al., 1991; Warman et al., 1993; Wright and Mayne, 1988) and the glycosaminoglycan, hyaluronan (HA) (Hogan et al., 1971b; Sebag, 1989b; Meyer and Palmer, 1934). A collagen network of heterotypic fibrils (types II, V/XI and IX) presumably maintains the gel structure, and HA fills the spaces between these collagen fibrils and stabilizes the gel (Fig. 1) (Swann, 1980; Bishop, 2000; Balazs, 1961).
The highly hydrated, almost acellular vitreous body of the human eye consists of only 0.1% macromolecules, of which collagens are the most important for its matrix structure. During embryological development, the human vitreous body is a highly dynamic matrix, in which the primary (vascular) vitreous is gradually replaced by the secondary (avascular) vitreous. With aging, the human vitreous undergoes a slowly progressive remodelling, characterized by the gradual formation of collagenous condensations and liquefied spaces in the gel structure. The former is probably the result of collagen synthesis and the deposition of newly formed collagen into the matrix, while the latter is probably due to collagen breakdown. Therefore, remodelling of the vitreous matrix starts at a very early age and continues into old age, albeit at a slower pace. Older theories and concepts of a strict spatial separation between the primary and secondary vitreous during embryonic development, and morphological changes in the aging vitreous being due to a simple aggregation of collagen fibrils are questioned. This review describes the embryological and postnatal remodelling of the human vitreous matrix and vitreoretinal interface, in addition to the mechanisms and cells that are potentially involved in this process.
Cellular origin, formation and turnover of the vitreous
2010, Encyclopedia of the Eye
The vitreous body (VB) is a gelatinous extracellular matrix (ECM) structure that fills the posterior cavity of the eye. It is composed of about 40 ECM and a long list of non-ECM proteins, such as albumin, tranferrin, and vitellogenin. Major protein constituents for the embryonic chick vitreous ECM are collagen II, V/XI, IX, fibrillin, and fibronectin. In situ hybridization showed that the prominent site of synthesis for most of these ECM proteins is the ciliary body with minor contributions from the retina, the hyaloid vasculature, and the optic disk. Quantification of protein and messenger RNA (mRNA) expression levels showed high concentrations of the ECM proteins and their mRNAs in the embryonic eye and very low concentrations in the adult eye. Further analysis revealed a precipitous downregulation of VB protein synthesis during late embryogenesis and early postnatal life. The major postnatal downregulation of the de novo synthesis of VB ECM proteins indicates that the vitreous ECM is maintained with little turnover throughout the adult life. The data are consistent with the fact that the VB gel undergoes an age-dependent liquefaction, a continuous and irreversible loss of collagen IX along the collagen II fibrils, and the fact that the ECM network of the VB does not regenerate after vitrectomy.
Cellular origin, formation and turnover of the vitreous
2010, Encyclopedia of the Eye, Four-Volume Set
The vitreous body (VB) is a gelatinous extracellular matrix (ECM) structure that fills the posterior cavity of the eye. It is composed of about 40 ECM and a long list of non-ECM proteins, such as albumin, tranferrin, and vitellogenin. Major protein constituents for the embryonic chick vitreous ECM are collagen II, V/XI, IX, fibrillin, and fibronectin. In situ hybridization showed that the prominent site of synthesis for most of these ECM proteins is the ciliary body with minor contributions from the retina, the hyaloid vasculature, and the optic disk. Quantification of protein and messenger RNA (mRNA) expression levels showed high concentrations of the ECM proteins and their mRNAs in the embryonic eye and very low concentrations in the adult eye. Further analysis revealed a precipitous downregulation of VB protein synthesis during late embryogenesis and early postnatal life. The major postnatal downregulation of the de novo synthesis of VB ECM proteins indicates that the vitreous ECM is maintained with little turnover throughout the adult life. The data are consistent with the fact that the VB gel undergoes an age-dependent liquefaction, a continuous and irreversible loss of collagen IX along the collagen II fibrils, and the fact that the ECM network of the VB does not regenerate after vitrectomy.
Effects of fibrillin-1 degradation on microfibril ultrastructure
2007, Journal of Biological Chemistry
Current models of the elastic properties and structural organization of fibrillin-containing microfibrils are based primarily on microscopic analyses of microfibrils liberated from connective tissues after digestion with crude collagenase. Results presented here demonstrate that this digestion resulted in the cleavage of fibrillin-1 and loss of specific immunoreactive epitopes. The proline-rich region and regions near the second 8-cysteine domain in fibrillin-1 were easily cleaved by crude collagenase. Other sites that may also be cleaved during microfibril digestion and extraction were identified. In contrast to collagenase-digested microfibrils, guanidine-extracted microfibrils contained all fibrillin-1 epitopes recognized by available antibodies. The ultrastructure of guanidine-extracted microfibrils differed markedly from that of collagenase-digested microfibrils. Fibrillin-1 filaments splayed out, extending beyond the width of the periodic globular beads. Both guanidine-extracted and collagenase-digested microfibrils were subjected to extensive digestion by crude collagenase. Collagenase digestion of guanidine-extracted microfibrils removed the outer filaments, revealing a core structure. In contrast to microfibrils extracted from tissues, cell culture microfibrils could be digested into short units containing just a few beads. These data suggest that additional cross-links stabilize the long beaded microfibrils in tissues. Based on the microfibril morphologies observed after these experiments, on the crude collagenase cleavage sites identified in fibrillin-1, and on known antibody binding sites in fibrillin-1, a model is proposed in which fibrillin-1 molecules are staggered in microfibrils. This model further suggests that the N-terminal half of fibrillin-1 is asymmetrically exposed in the outer filaments, whereas the C-terminal half of fibrillin-1 is present in the interior of the microfibril.

View all citing articles on Scopus

View full text

Vitreous humor of chicken contains two fibrillar systems: An analysis of their structure

Abstract

J. Biol. Chem

Cell

Cell

J. Biol. Chem

J. Mol. Biol

FEBS Lett

Differentiation

Dev. Biol

Tissue Cell

J. Biol. Chem

Biochem. Biophys. Res. Commun

J. Ultrastruct. Res

J. Ultrastruct. Res

Dev. Biol

Exp. Eye Res

J. Biol. Chem

Biochem. Biophys. Res. Commun

Biochem. J

Exp. Eye Res

Cancer Res

J. Cell Biol

J. Ultrastruct. Res

J. Cell Biol

J. Cell Biol