Topography of lymphatic markers in human anterior uvea

Abstract

Purpose: Reports of lymphatics in the anterior human uvea are contradictory. This might be caused due to a certain topography which has not been considered yet. Therefore we here systematically analyze iris and adjacent ciliary body with immunohistochemistry by combining various lymphatic markers.

Methods: Meeting the Declaration of Helsinki, human iris and ciliary body were obtained from cornea donors and prepared for cryosectioning. Cross sections of tissue blocks at 12, 3, 6, 9 o`clock position and at all corresponding intersections (i.e., 1.30, 4.30, 7.30, 10.30) were processed for immunohistochemistry of the following lymphatic markers: LYVE1, podoplanin, PROX1, FOXC2, VEGFR3, CCL21. Additionally applying DAPI, double, triple and quadruple combination of aforementioned markers were documented using confocal microscopy.

Results: In the iris, LYVE 1 positive cells of various morphology were distributed throughout the non-pigmented part. These cells were lacking podoplanin. Numerous podoplanin positive cells were mainly located at the anterior border of the iris. These cells were not colocalized with LYVE1 or PROX1, FOXC2, CCL21, VEGFR3. While podoplanin positive cells were only rarely detected posteriorly of the iris root, many LYVE1 positive cells were also present within the cilary muscle and ciliary body villi. In the ciliary muscle, occasionally podoplanin+ vessel-like structures were detectable, but these were never colocalized with LYVE-1. Similar vessel-like structures immunoreactive for VEGFR3 never displayed PROX1 or CCL21. A certain topography of structures at the various uvea-positions investigated was not obvious.

Conclusions: Structures colocalizing for at least two lymphatic markers were not detectable at positions investigated, and further a certain topography was not obvious. Putative lymphatic channels of the anterior uvea therefore might display a different marker panel than generally presumed.

Keywords: 554 immunohistochemistry • 419 anatomy • 745 uvea