Comparison of Rotary and Cryostat Microtomes in the Skeletochronology on Green Turtle Humerus Bones

Skeletochronology is a powerful tool that provides information on the age of sea turtles. Digital images of histologically prepared humerus bone sections are commonly used for age determination. The quality of digital images, which is critical for robust age estimation, varies depending on the type and histological technique associated with microtome. This study aimed to compare the quality of digital image sections of humerus bones prepared by rotary and cryostat microtomes. The humerus bones of 11 juvenile stranded (dead) green turtles (mean CCL 292.1 mm) on Samandağ beach during the 2021 nesting season were used for the study. Three readers scored the quality of histologic sections prepared with two different microtomes and associated protocols, as well as the readability of the lines of arrested growth (LAGs), which they saw from 0 to 5. The Wilcoxon-signed rank-paired test was used to ascertain the disparities between the quality scores of the two protocols. In addition, the compatibility of readers was evaluated by determining the proportion of specimens with at least two identical scores for each protocol. The scores obtained from the cryostat microtome protocol had a wider variation compared to the rotary microtome protocol. The rotary microtome protocol has higher median score values (4) than the cryostat microtome protocol (3) (p