Abstract
Purpose: :
To determine the localization of Notch1 in the fetal human retina, choroid, and the fetal vasculature of vitreous (FVV).
Methods: :
Fetal human eyes from 7-21 weeks gestation (WG) were cryopreserved and sections were incubated with rabbit anti-human Notch1 (Spring Bioscience) and mouse anti human CD31(Dako) or mouse anti-human vimentin (Abcam) followed by FITC and Cy5 labeled secondary antibodies as previously reported (Hasegawa et al. Dev Dyn 236:2089, 2007). Specimens were analyzed with a Zeiss Meta510 confocal microscope.
Results: :
Notch1 expression was very low in the 7 WG FVV but very prominent in FVV at 12 and 17 WG. Localization to endothelial cells (EC, CD31+) nucleus and nucleoli was striking. In choroid at 7 WG, Notch1 was prominent in erythroblasts and angioblasts in the islands of progenitors undergoing hemovasculogenesis. At later ages, Notch1 was associated with some EC in developing choroidal blood vessels, where nuclear localization was also observed. In retina, there was no Notch1 at 7 WG but localization was prominent in the Muller cells (vimentin+) at 10, 12, 17 and 21 WG. The most prominent Notch1 labeling was in inner Muller cell processes from neuroblastic layer to inner limiting membrane but there were also nuclei positive in inner neuroblastic layer. In all cells with nuclear labeling in the eye, the Notch1 was present in distinct sub-nuclear bodies.
Conclusions: :
During development of the FVV and the choroidal vasculature, Notch1 is expressed in vascular precursors and EC. During hemo-vasculogenesis, erythroblasts also expressed Notch1. During the gestational period studied, Notch1 was not expressed in developing human retinal blood vessels during vasculogenesis. Others have reported Notch1 in EC during mouse blood vessel development by angiogenesis. The most prominent expression during human fetal retinal development was in Muller glia from 10-21 WG. Localization of Notch in sub-nuclear bodies was common in all tissues studied.
Keywords: development • blood supply • retinal glia