Intracapsular Organization of Ciliary Zonules in Monkey Eyes

Abstract

Ciliary zonules are responsible for changing the curvature of a lens in the dioptric focus of an eye. Present established theory is based on the relaxation of zonular superficial fasciculi affixed to the capsular surface, thereby inducing the change of anterior-and posterior lens curvature causing spontaneous liquid movement of lens material. To achieve precise focusing at any distance, a more active functional organization should exist. The present studies were performed to determine not only the surface attachment but also the intracapsular affix of zonules on monkey eyes. In addition, the development of focusing in newborn and presbyopia is analyzed. Histology was prepared by conventional and molecular immunofluorescence stainings on the compositions of zonules with fibrillin-1 (FBN 1) and lens capsule with collagen IV (COL IV), and in situ hybridization (ISH) analyses on frozen sections. Superficial circumferential attachments of zonule were found radially oriented between ciliary processes and anterior/posterior lens capsules forming a triangular figure. Two functional intralayer integrations were found above them; anteriorposterior crossed fibers over the equator and radial fibers distributed toward the anterior or posterior polar areas. These fibers were bound tightly to the deep layer connective tissues close to the lens epithelium. Fine zonular fibers were aggregated, gradually forming bundles and bifurcated again on the way to the capsule. The lateral striped staining pattern in bundles suggested their elastic nature. Response of a-helixes of collagen IV immunostaining was more positive on a-1,2,4 than a-3,5,6 on anterior-and posterior lens capsules. Newborn eyes revealed not fascicular but fine membranous zonules on the lens surface and small ciliary processes. ISH analysis revealed high synthetic expression of FBN 1 mRNA in cytoplasm of nonpigmented epithelial cells of ciliary processes. The synthetic expression of FBN 1 declined with aging.

The Effect of Ultraviolet B on Fibrillin-1 and Fibrillin-2 in Human Non-pigmented Ciliary Epithelial Cells <i>In Vitro</i>

“…The ciliary zonule is composed of fibrillin-based microfibrils [9, 18]. Rotary shadowing images of fibrillin-based microfibrils extracted from COS-1 cell/matrix layers exhibit beaded filaments with a periodicity of 56 nm [19].…”

Nonselective Assembly of Fibrillin 1 and Fibrillin 2 in the Rodent Ocular Zonule and in Cultured Cells: Implications for Marfan Syndrome

“…[4][5][6]30,41,44,45 In the absence of a comprehensive analysis of embryonic human eyes, however, it is presently unclear whether fibrillin 2 is a component of the human zonule during its development.…”

Matrix Metalloproteinase-2 Degrades Fibrillin-1 and Fibrillin-2 of Oxytalan Fibers in the Human Eye and Periodontal Ligaments <i>In Vitro</i>

“…On the other hand, lens epithelial cells are reported to express various MMPs [13]. Lens epithelial cells do not contribute to the production of the ciliary zonule because they lack expression of fibrillin-1 and fibrillin-2 [12, 24]. However, they may control the remodeling of the lens and contribute to zonule degradation.…”