Abstract
Purpose:
To characterize the expression of the lymphangiogenic marker podoplanin (clone D2-40) in human fetal eyes with regard to a maturation-dependent localization and expression and the nondistinctive finding of lymphatic structures in the choroid.
Methods:
40 formalin-fixed paraffin-embedded eyes from 40 human fetuses (age range: 10 to 32 weeks of gestation (WoG)) were investigated. The cohort consisted of 22 male and 14 female fetuses (gender was unknown in 4 cases). Immunohistochemical stains were performed for D2-40 and - as control for endothelial reactivity - for CD34. A semiquantitative analysis of immunoreactivity in different segments of the eye was performed by light microscopy. The intensity of staining was graded with a score ranging from 0 to 3. Statistical analysis was performed with SPSS (IBM SPSS Statistics 20; Armonk, NY). The probability for the alpha error was set to p < 0.05.
Results:
Podoplanin was expressed in the human fetal eye of 10 - 32 WoG. Immunoreactivity was found with a varying intensity in 39 of 40 eyes (97.5%). It was seen in vascular structures of the conjunctiva as well as in conjunctival epithelium, chamber angle, and optic nerve sheaths. In addition, labelling of the corneal endothelium was detected in four eyes (10, 12, 17, 18 WoG). In some specimens (n = 14) a slight, equivocal staining reaction was noted in the choroid. However, no definite intraocular lymphatic vessels resp. their progenitors were found. There was no correlation of antigen immunoreactivity and the gestational age except for the endothelial reactivity that was found in fetuses younger than 19 WoG (p = 0.002).
Conclusions:
Podoplanin (D2-40) is, even at an early gestational age, expressed in several structures of the human fetal eye and the ocular adnexae that are not necessarily associated with future lymphatic vessels. Thus, it may play a role in the fetal ocular development. In particular, D2-40 reactive structures were found in the choroid and the chamber angle but no lymphatic vessels or their progenitors could not be unequivocally identified at these sites.
Keywords: 554 immunohistochemistry •
497 development