Striae of Retzius — MFDS Part 1 MCQ
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Correct answer: A — Long-period incremental growth lines produced by rhythmic ameloblast activity during enamel formation
The correct answer is A. Striae of Retzius are long-period incremental markings recording rhythmic enamel formation by ameloblasts. They are distinct from the daily prism cross-striations in option C, which represent the approximately 24-hour secretory rhythm. Option B describes Hunter–Schreger bands, an optical effect caused by changes in the direction of groups of enamel prisms. Option D describes enamel lamellae, which are thin hypomineralised defects extending inward from the enamel surface. Option E describes enamel tufts, hypomineralised structures arising at the dentinoenamel junction. Thus, only option A identifies the developmental incremental lines represented by the striae of Retzius.
Reference: Shellis RP. Utilization of periodic markings in enamel to obtain information on tooth growth. Journal of Human Evolution. 1998;35(4–5):387–400. https://pubmed.ncbi.nlm.nih.gov/9774501/