The collagen matrix of the human trabecular meshwork is an extension of the novel pre-Descemet's layer (Dua's layer)

Background The trabecular meshwork (TM) located at the angle of the anterior chamber of the eye contributes to aqueous drainage. A novel layer in the posterior part of the human cornea has recently been reported (the pre-Descemet's layer (Dua's layer (PDL)). We examined the peripheral part of this layer in relation to the origin of the TM. Methods The PDL and TM of 19 human donor eyes and one exenterated sample were studied. Samples were examined by light and electron microscopy (EM) for tissue architecture and by immunohistology for four matricellular proteins, five collagen types and CD34. Results EM revealed that beams of collagen emerged from the periphery of PDL on the anterior surface of the Descemet's membrane and divided and subdivided to continue as the beams of the TM. Long-spacing collagen was seen in the PDL and TM. Trabecular cells (CD34-ve) associated with basement membrane were seen in the peripheral part of the PDL and corresponded to the start of the separation of the collagen lamellae of PDL. Collagen VI was present continuously in PDL and extended into the TM. Matricellular proteins were seen predominantly in the TM with only laminin extending into the periphery of PDL. Conclusions This study provides an insight into the origins of the collagen core of the TM as an extension of the PDL of the cornea. This finding adds to the knowledge base of the TM and cornea and has the potential to impact future research into the TM and glaucoma.