MHC-II expression of Iba-1+ cells in retinal whole-mounts after 15 days of laser-induced OHT. Double immunofluorescence staining for Iba-1 (in red) and MHC-II (in green). A-C: in naïve retinas, a constitutive weak expression of MHC-II (arrowheads) was observed in some Iba-1+ cells throughout the retina (B). However, some Iba-1+ cells located in the juxtapapillary area and in the far periphery (A, inset) had a strong constitutive expression of MHC-II (B, inset). E-H: in contralateral eyes, Iba-1+ microglial cells of the retina had morphological changes (H) and showed a stronger expression of MHC-II immunoreaction throughout the retina (F,G) in comparison with naïve (B-D). I-L: Iba-1+ cell in OHT-eyes had a similar up-regulation of MHC-II (J-K) as did contralateral eyes (F-G); however, the cell bodies were larger and the processes thicker and more retracted (L) than in the contralateral (H) retinas. Fluorescence microscopy and image acquisition using the ApoTome. Iba-1, ionized calcium binding adaptor molecule 1; MHC, major histocompatibility complex; OHT, ocular hypertension.