Development of cytoskeleton in neuroectodermally derived epithelial and muscle cells of the human eye.

PURPOSE To analyze the cytoskeletal development in neuroectodermally derived epithelial and muscle cells of the human eye during the second and third trimesters of pregnancy. METHODS Nine formalin-fixed, paraffin-embedded fetal autopsy eyes from the 13th to 40th week of gestation were studied with eight monoclonal antibodies (mAbs) to intermediate filaments and alpha-smooth muscle actin (alpha SMA) by the avidin-biotinylated-peroxidase complex method. RESULTS The epithelium of the iris reacted with mAbs Vim 3B4 and V9 to vimentin in all eyes. Reactivity with mAb CAM 5.2 to cytokeratin (CK) 8 and mAb CY-90 and KS-B17.2 to CK 18 disappeared from the iris epithelium by the 28th gestational week. mAb 1A4 to alpha SMA labeled its anterior layer from the 28th week on. mAbs DE-U-10 and D33 to desmin labeled dilator fibers by the 37th week, and focal reactivity for CK 8 and 18 concurrently appeared. The developing iris sphincter reacted for alpha SMA in all eyes. It was labeled increasingly for desmin from the 18th week on, whereas initial reactivity for vimentin gradually disappeared after the 22nd week. mAbs to vimentin, CK 8, and CK 18 labeled the ciliary epithelium and the retinal pigment epithelium in all eyes, except for lack of CK 8 and 18 in the nonpigmented ciliary epithelium at the 13th week. The ciliary muscle reacted uniformly for vimentin and alpha SMA and from the 16th week on for desmin. CONCLUSIONS The results highlight the individuality of cytoskeletal profiles in the neuroectodermal epithelial and muscle cells of the eye and clarify the formation of the peculiar cytoskeleton typical of the adult human eye. They also offer a framework for detecting cytoskeletal changes in developmental anomalies of the eye after the first trimester of pregnancy.