| Summary: | Studies were carried out on the optic nerve of a variety of inbred strains and their F<SUB>1</SUB> hybrids. The postnatal development of a variety of different age groups was also analysed to provide baseline data as part of a study to determine the teratogenic effect of prenatal exposure to alcohol on the postnatal development of the optic nerve in this species. Furthermore, the optic nerve from adult <I>Small</I> <I>eye</I> (<I>Sey</I>) mice was analysed to determine the effects of the <I>Sey</I> gene mutation on the optic nerve of the mouse. Parameters analysed were mean cross-sectional area (csa), mean myelinated nerve fibre count, mean myelinated nerve fibre density and myelinated nerve fibre spectrum. Intra-strain and inter-strain comparisons of these parameters were carried out. Developmental events such as the onset and progression of myelinogenesis were also examined. The findings indicated that there was neither a significant difference in any of the parameters studied between the left and the right optic nerves nor evidence of sexual dimorphism within any of the strains studied, although, a significant degree of inter-strain variation was noted. As has previously been reported, the mouse is similar to other rodents and most primates in that the nerve fibres in the adult optic nerve are all myelinated. These fibres are unimodally distributed (i.e. having only one peak) along the nerve fibre diameter spectrum, which is also positively skewed (i.e. skewing is to the right in favour of the large diameter fibres). However, in the mouse, the mean myelinated nerve fibre count is lower than that reported in all primates so far studied, and the spectrum of distribution of the nerve fibres is narrower. During postnatal development, the optic nerve in the mouse grows rapidly during the early part of the juvenile period (first three postnatal weeks).
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