Abstract
Purpose :
Establishment of the anterior segment is an essential event during formation of the visual system. Failure of anterior segment formation is likely to results in anterior segment dysgenesis and or predisposition to glaucoma. Thus, understanding the developmental events and regulatory mechanisms governing anterior segment formation are crucial for any significant advancement in screening or treatment of anterior segment disorders. The anterior segment is largely assembled from neural crest derivatives generally identified as periocular mesenchyme (POM). In order to uncover the developmental underpinnings likely to drive anterior segment dysgenesis we have begun to comprehensively characterize POM identity, behavior and function during formation of the zebrafish eye.
Methods :
Quantification of POM cell targeting to the anterior segment was performed using 3D confocal imaging of zebrafish POM transgenic reporter lines, Tg[FoxC1b:GFP], Tg[FoxD3:GFP] and Tg[Pitx2:GFP]. We collected 3D images of anterior segment associated GFP expressing cells at 24, 26, 28, 32, 48 and 54hpf and counted the number of cells found within four quadrants of the anterior segment. (dorso-nasal DN, dorso-temporal DT, ventral-nasal VN, ventral-temporal VT). Migration dynamics in FoxC1b and FoxD3 expressing cells was assessed by performing in vivo time-lapse confocal imaging of transgenic embryos from 22-48hpf. Sex of the embryos could not be determined and was therefore random.
Results :
Our preliminary findings indicate that during early colonization of the eye, FoxC1b expressing POM preferentially target the dorsal-temporal (53.7% +/- 5.3, n=25) and ventral-temporal regions (25.6% +/- 4.5, n=25) of the eye followed by targeting to the ventral regions, while FoxD3 expressing POM primarily target dorsal-temporal (52.5% +/- 6.2, n=24) and dorsal-nasal regions (39.6% +/- 3.3, n=24) with much lower affinity for the ventral regions (8.1%+/- 4.4, n=24). Migration tracking in live imaging studies confirms our quantification results.
Conclusions :
Overall, our work aims to re-define the population of POM that specifically target the anterior segment as the Anterior Segment Mesenchyme (ASM) and comprehensively characterize their molecular, migratory and targeting signatures.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.