Fig. 1

Tetrahydrobiopterin (BH4) deficiency is associated with morphological changes in the eye. a Representative images of the eyeballs from wild type (WT) and hph-1 mice analyzed by H&E staining at postnatal day 22 (P22). The pictures show a reduction in the size, as well as, a persistence of fetal hyaloid vasculature in the eyes of hph-1 (arrows). b Representative images of the anterior eyeball showing that the iris appeared hypertrophic, causing the pupil to be smaller or absent in an eye of hph-1 mice at P22, but not in WT. c BH4 content (ng/mg of tissue) in retinas from control (WT) and hph-1 mice at P22 was measured by using liquid chromatography tandem mass spectrometry (LC-MS/MS). The levels of BH4 were significantly decreased by ~ 90% in the retinas of hph-1 compared with WT mice. Results showed in the histograms are expressed as means ± SEM of n = 3 mice for each group. **p < 0.005