Arrangement of the Sclerocorneal Trabecular System in Human Fetuses

Abstract

By studying the eyes of 20 human fetuses 33–326 mm in length (8 to 36 weeks gestation) with the light and scanning electron microscope we show that the sclerocorneal and the uveal trabecula cannot be considered as independent structures, since embryologically and morphologically they are the sclero-corneo-iridal insertions of the longitudinal fibres of the ciliary muscle.

Qualitative changes in fetal trabecular meshwork fibers at the human iridocorneal angle

“…They confirmed the connection between the ciliary muscle and the TM, which had been ruled out by other researchers [10, 11]. According to Ruano-Gil et al [9], the ciliary muscle insertions are divided into 3 layers: 1) an outer layer corresponding to the scleral spur, 2) a middle layer corresponding to Schlemm's canal, and 3) an inner layer corresponding to Descemet's membrane of the cornea.…”

“…These structures would be unlikely to conduct tensile stress from the extending iris. In contrast, Ruano-Gil et al [9] hypothesized that mechanical forces induced TM differentiation in human fetuses with the aid of tensile stress that was generated by the ciliary muscle. They confirmed the connection between the ciliary muscle and the TM, although their figures did not include the topographical anatomy around the TM.…”

“…Anderson's scheme [7] is simple, but it appears to be a great improvement over the scenario proposed by Hansson and Jerndal [8], whose diagram is detailed but does not demonstrate the relative topographical changes that occur between the angle and the ciliary muscle. Using SEM observations of human fetal eyes (8-36 weeks of gestation), Ruano-Gil et al [9] also hypothesized that mechanical forces induced TM differentiation with the aid of tensile stress generated by the ciliary muscle at 25 weeks of gestation. They confirmed the connection between the ciliary muscle and the TM, which had been ruled out by other researchers [10, 11].…”