BNP mRNA was detected by ISH in the NFL, GCL, and inner nuclear layer (INL), of fetal and postnatal macaque retinas (
Fig. 3). The most intense expression of
BNP was in GCs of the central macula, although neurons in the inner and outer regions of the INL also expressed
BNP. Co-localization of
BNP mRNA with anti-GFAP/-vimentin in end-foot-like structures at the retinal surface (
Figs. 3A–C, arrowheads) and in radial processes in the INL and inner plexiform layer (IPL;
Figs. 3E–G, arrows) indicates that
BNP mRNA is expressed in Müller cells. Co-localization of
BNP mRNA with vimentin-/GFAP-IR in the somas of stellate cells deep in the GC layer, indicates that
BNP is also expressed in the somas of the retinal astrocytes that accompany the developing perifoveal vessels (
Figs. 3A–C, oblique arrows). However,
BNP mRNA was absent from the astrocyte processes (
Figs. 3A–C, vertical arrows). Similar patterns of
BNP expression were seen in the foveal regions of an additional six animals aged between Fd 55 and 11 yo. The sense riboprobe produced no specific labeling (
Fig. 3D). Optical densitometry (
Fig. 3H) indicates that, by Fd 55, levels of
BNP are higher temporally compared with nasal retina and that a clear peak of
BNP expression, which is maintained into adulthood, emerges at the developing fovea by Fd 80.