Ultrastructural Modelling of the Matrix-Cilium-Golgi Continuum in Hyaline Chondrocytes

Michael John Jennings
2015 Zenodo  
Overlooked for decades as an evolutionary vestigial organelle, the primary cilium has recently become the focus of intensive investigations into understanding of the physical structure and processes of eukaryote cell function. The cilium is central to various signalling pathways and modalities for signalling, allowing centrosomal processing and regulation of cellular and organelle function. The enigmatic processes of their nanoscale ciliogenesis and sensory function at present remain poorly
more » ... rstood. Dysfunction of their normal function or component proteins correlates with a wide spectrum of diseases, or ciliopathies, which express as developmental disorders and pathologies. Normal connective tissue function requires cells to sense and respond to mechanical and physiochemical changes in the extracellular environment, and matrix, in order to maintain their form and function. In hyaline cartilage, chondrocyte primary cilia are located at an intermediate position between the mechanically functional extracellular matrix (ECM) surrounding the cell, and the intracellular organelles responsible for producing, modifying, transporting and secreting extracellular matrix materials. While many cellular and physiological processes involving primary cilia are at present known, accurate in situ knowledge of their form and fine structure in connective tissue is lacking. A three dimensional model has been created of an in situ chondrocyte primary cilium. This details the anatomical structure of the cilium and its relationship to other cellular organelles. Components were mapped and divided into groups containing: the Matrix, the Cilium, the Centrosome, the Golgi apparatus and the Nucleus. The extracellular matrix was found to consist of interconnected tethered proteoglycans and matrix granules, with the granules composed of aggregates of finer components. These are tethered to the ciliary membrane at localised binding points. The membrane itself was observed as a dynamic extension of the cell membrane, fitting neatly over the [...]
doi:10.5281/zenodo.4632565 fatcat:vyr7wbzun5fjxm4tu3r7n64vgi