Endothelial cell proliferation in the choriocapillaris during human retinal differentiation.
BACKGROUND
Differentiation patterns of the neural retina and its retinal vasculature are not well matched. The foveal region differentiates first, however the central retina is not vascularised until late in gestation. The authors explored the hypothesis that higher rates of endothelial cell proliferation in the choriocapillaris of the central retina might compensate for the slow growth of central retinal vessels, providing supplementary nutrients to the region during the early stages of neuronal maturation.


METHODS
Frozen sections of five human fetal eyes (14-18.5 weeks' gestation), were examined for Ki-67 and CD34 immunoreactivity using confocal microscopy. Measurements of choriocapillaris area and the number of proliferating choroidal endothelial cells were used to calculate the rate of choroidal endothelial proliferation at five different chorioretinal locations.


RESULTS
The choriocapillaris area is consistently greater in the foveal region than at other locations and increases progressively with age. A higher rate of endothelial cell proliferation was found in parts of the choriocapillaris associated with the undifferentiated (proliferating) neural retina, compared with the differentiated, central region.


CONCLUSIONS
The findings suggest that mechanisms regulating proliferation and growth of the choroidal vasculature are independent of differentiation in the neural retina, and are thus profoundly different from mechanisms that regulate formation of the retinal vasculature.
Allende
A
A
Discipline of Clinical Ophthalmology and Save Sight Institute, University of Sydney, GPO 4337, Sydney, NSW 2001, Australia. alexa@med.usyd.edu.au
Madigan
M C
MC
Provis
J M
JM
D002454:Cell Differentiation; D049109:Cell Proliferation; D002829:Choroid / Q000196:embryology*; D042783:Endothelial Cells / Q000166:cytology; D047109:Fetal Development; D005865:Gestational Age; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018613:Microscopy, Confocal; D012160:Retina / Q000196:embryology*; D012171:Retinal Vessels / Q000196:embryology