Purchase this article with an account.
F Mabuchi, JD Lindsey, M Aihara, RN Weinreb; Distribution of Axons in the Normal Mouse Optic Nerve . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4055.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine whether axon denstity varies among the central, mid-peripheral, or peripheral margin positions in normal mouse optic nerves. Methods: Eight weeks old black Swiss mice were euthanized and the optic nerves were processed conventionally for electron microscopy. Ultrathin sections of the optic nerve were cut perpendicularly to the long axis of the nerves at approximately 300 mm from the posterior pole of the eye. For each optic nerve cross-section, electron micrograph was taken at 200X magnification to measure the area of the optic nerve cross-section. Then a series of 20 micrographs were taken at 10000X magnification in the following positions within the nerve: center, 4 micrographs; mid-periphery, 8 micrographs; peripheral margin, 8 micrographs. No adjustments in position were made with respect to the tissues including blood vessels and glial cells. The axons in each high magnification micrograph were counted using unbiased counting rules. The total axon population was estimated by multiplying the average density of axons by the area of the optic nerve cross-section. Results: Mean optic nerve area was 41287±10513(SD) mm2 (N=6). Mean total number of axons was 37728±9250. Mean of the average axon density (axons/mm2) was 0.92±0.086. The density distribution was as follows: center 1.099±0.23, mid-periphery 0.96±0.12, peripheral margin 0.78±0.077. Comparison of the axon density in the three regions by ANOVA showed difference among the three groups (P = 0.0093). Bonferroni t test analysis showed that axon density in the center region was significantly more than the peripheral region (P = 0.0027). Conclusion: The increased axon density in the central region raises the possibility of decreased susceptibility of the central axons to damage from high intraocular pressure.
This PDF is available to Subscribers Only