Morphology of the murine optic nerve.
OBJECTIVE
To study the morphology of the murine optic nerve (ON).


METHODS
Eyes of C57/Bl6 and BalbC mice were studied by light and electron microscopy. Microvascular castings of the ON region were prepared by transcardial injection of liquid plastic and studied with a scanning electron microscope. Immunohistochemistry was performed using antibodies against glial fibrillary acidic protein (GFAP), connexin 43, carbonic anhydrase II, and collagen types I and III.


RESULTS
The transition between nonmyelinated and myelinated portion of the ON started approximately 0.6 mm behind the globe. A lamina cribrosa was completely absent. Instead, ON axons passed through a scleral hole that was surrounded by a ring of type III and type I collagen fibers. Instead of connective tissue beams within the nerve, layers of elongated astrocytes traversed the ON. All astrocytes stained for GFAP, but not for carbonic anhydrase II. The arterial supply of the nonmyelinated ON derived from branches of the central retinal artery. None of the capillaries derived from choroidal vessels.


CONCLUSIONS
The mouse ON head differs from that of other species, because it lacks a lamina cribrosa and a choroidal vascular supply. Studies in glaucomatous mice might help to identify the importance of the lamina cribrosa and the choroidal vascular supply for optic nerve damage in glaucoma.
May
Chr Albrecht
CA
Department of Anatomy II, Friedrich Alexander University, Universitätstrasse 19, D-91054 Erlangen, Germany. atmay@anatomie.uni-erlangen.de
Lütjen-Drecoll
Elke
E
D000818:Animals; D024402:Carbonic Anhydrase II / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D024061:Collagen Type III / Q000378:metabolism; D018031:Connexin 43 / Q000378:metabolism; D016319:Corrosion Casting; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008855:Microscopy, Electron, Scanning; D009880:Ophthalmic Artery / Q000648:ultrastructure; D009900:Optic Nerve / Q000098:blood supply / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure
D024042:Collagen Type I; D024061:Collagen Type III; D018031:Connexin 43; D005904:Glial Fibrillary Acidic Protein; D024402:Carbonic Anhydrase II