A direct contact between astrocyte and vitreous body is possible in the rabbit eye due to discontinuities in the basement membrane of the retinal inner limiting membrane

Abstract

Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization) and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3) or whole pieces (N = 3) of the medullated nerve fiber region of threemonth-old male rabbits (Orictolagus cuniculus) were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long) of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body.

Impaired glucose tolerance plus hyperlipidaemia induced by diet promotes retina microaneurysms in New Zealand rabbits

“…It has been known for years that some types of astrocytes are located around or between the vitreous blood vessels that run on the inner surface of the medullated nerve fibres of the rabbit retina. These anatomical structures are referred to as glial tufts and are located between the blood vessels and the inner limiting membrane of the rabbit retina, appearing as early hyperfluorescent dots in the fluorescein angiography (Haddad et al. 2003).…”

Hyperconvolution of the inner limiting membrane in vitreomaculopathies

“…Although such breaks in the ILM have been shown in rabbits [30] they are uncommon in human eyes, and it has been suggested that such breaks could result from minor trauma and then heal over [20]. Alternatively, experimental evidence indicates that glial cells may migrate through an intact ILM [9].…”

Fundus Photography, Fundus Fluorescein Angiography, and Optical Coherence Tomography of Healthy Cynomolgus Monkey, New Zealand Rabbit, Sprague Dawley Rat, and BALB/c Mouse Retina

“…The large eyeball of the New Zealand rabbit permits easy experimental manipulation, measurement, and dissection, and so is widely used in ophthalmologic research. However, FP and FFA revealed two notable differences compared to human retina, a larger optic disc and myelinated retinal nerve bers [17,18]. There were also substantial differences in the growth pattern of retinal vessels compared to the human retina.…”