Cellular localization of
OPA1 mRNA in the mature and developing rodent retina by in situ hybridization. (
A)
OPA1 antisense riboprobes in retina radial sections of adult rat and (
B) mouse. Cells in the GCL (
arrows) were clearly stained, and cells in the inner half of the INL (
arrowheads) were occasionally stained. The most intense
OPA1 expression occurred in the cell bodies of the GCL, where, besides these vigorously stained cells (
filled arrows), cells with a less intense staining (
open arrows) were present. The outer retina (ONL, PhR) was free of any staining. (
C) Control experiments with the
OPA1 sense probe did not show any detectable signal over the entire retina. (
D) To verify the specificity of the in situ hybridization protocol, a rhodopsin antisense probe was used as a positive control. It exclusively labeled the outer retina (

; ONL of the photoreceptors) leaving the inner retina unstained. (
E,
F) Radial sections of rodent retinas at various developmental stages between P3 and P20 hybridized with digoxigenin-labeled
OPA1 riboprobes. In the developing rodent retina only the GCL and the adjacent IPL have already separated from the NBL at P3, with the GCL still being multilayered but in the process of losing its supernumerous cells during the next days of development. (
E) In the rat retina, at P3 and P5, a clear
OPA1 expression was present in cell bodies of the multilayered GCL (
arrows) and in the proximal cytoplasm of cells located in the undifferentiated NBL along the IPL border (
arrowheads). At P10, when the INL is completely separated from the photoreceptors, staining was confined to the GCL and the innermost row of the INL. This staining pattern then persisted in all later developmental stages. (
F) In the developing mouse retina, the staining pattern was essentially the same as in rats. There was a slight temporal delay in
OPA1 expression, which is consistent with the slower retinal development in the mouse compared with the rat—very faint, if any, positive reaction was visible before P5. Up to P10, there was a tendency for reaction deposits to be randomly scattered over the entire retina, including the outer layers (P5,

). Scale bar, 50 μm.