Abstract
Purpose: :
The pathogenesis of functional conditions affecting the lacrimal canaliculus is poorly understood. Little is known about the structural components of the extracellular matrix (ECM) supporting the canaliculus. We characterize the elastic fibre phenotype of pericanalicular ECM.
Methods: :
This study was conducted with local and regional ethical approval. Healthy lower eyelid tissue containing the nasolacrimal canalicular system obtained from the clear margins of 8 patients who underwent orbital exenteration, and cut into 5µm thick histological sections. Elastic fibres were detected using standard tinctorial methods. Verhöeff’s iron haematoxylin was used to stain mature elastic fibres (MEF). Gomori’s aldehyde fuchsin (GAF) was applied to identify MEF and elaunin fibres. Lillie’s oxidised aldehyde fuchsin (OxAF) was used to detect additional oxytalan fibres that are not detected by the other staining methods. Light microscopy assessment by independent histopathologists using semiquantative techniques grading abundance of elastic fibres on a short ordinal scale of 0-4 was performed. Distribution of fibres was descriptive only.
Results: :
All three staining methods showed dense staining of elastic fibres. Verhöeff’s showed rich collection of MEF (3.1) with an almost distinct layer within the ECM surrounding the epithelial basement membrane. OxAF (3.4) stained more fibres than GAF (3.0) indicating the presence of additional elaunin fibres. OxAF staining identified a denser mid-submucosal elastic fibre collection. In addition, the fibres closest to the epithelium basement membrane were well ordered in contrast more distant ECM areas where the elastic fibres were more loosely organised.
Conclusions: :
Staining of normal canaliculi revealed an abundance of different elastic fibre phenotypes within the canalicular submucosal ECM. The high density of elastic fibres suggests its importance in maintaining the normal lacrimal pump mechanism. Further research identifying changes in these elastic fibres in functional canalicular disorders is warranted.
Keywords: pathology: human • extracellular matrix • anatomy