Oxytalan Fibres — MFDS Part 1 MCQ
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Correct answer: E — Fibrillin-rich microfibrillar bundles lacking elastin, oriented mainly apico-occlusally and closely associated with blood vessels
Explanation lettering: C = shown as A · E = shown as B · D = shown as C · B = shown as D · A = shown as E
A is correct. Oxytalan fibres are fibrillin-rich bundles of microfibrils belonging to the elastic-fibre system, but they lack deposited elastin; describing them simply as immature elastin is therefore misleading. In the periodontal ligament they run predominantly apico-occlusally and are closely related to blood vessels, for which they may provide mechanical support. Sharpey's fibres are the mineralised insertions of the principal type I collagen fibre bundles, not oxytalan fibres. Type IV collagen is a basement-membrane component. Mature elastin-rich fibres are not the defining elastic-system fibre of healthy periodontal ligament, and oxytalan fibres are present in health rather than only in disease. Transseptal fibres are collagenous fibres connecting adjacent teeth and are not oxytalan fibres.
Reference: Kira-Tatsuoka M et al. Immunohistochemical expression of fibrillin-1 and fibrillin-2 during tooth development. Journal of Periodontal Research. 2015;50(6):714–720. https://pubmed.ncbi.nlm.nih.gov/25524144/