In this study, we investigated ontogenetic and sexual changes of the brain scaling as well as the scaling and the relative size of six major brain areas in the small-spotted catshark Scyliorhinus canicula from the Mediterranean Sea. The brain somatic index (0.31–1.25%) did not differ significantly between sexes but was significantly affected by size with smaller specimens exhibiting higher values. Brain growth exhibited negative allometry (allometric coefficient 0.634), not affected by sex or maturity status. The brain growth rate was found to be higher compared with a previous study from the Atlantic Ocean. Regarding the scaling of the brain areas, the olfactory bulbs scaled with positive allometry, the telencephalon and the diencephalon scaled with the same rate of negative allometry, the mesencephalon exhibited even higher negative allometry, while the cerebellum and the medulla oblongata both followed a close-to-isometric growth pattern. Immature S. canicula possessed a larger mesencephalon and diencephalon, highlighting the importance of vision in this life period, while mature specimens had enlarged olfactory bulbs, indicating that olfaction may be more important after the animal attains sexual maturity. In respect of sexual dimorphism, males had a larger cerebellum and medulla oblongata, while females had enlarged telencephalon and olfactory bulbs.

中文翻译：

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小斑点猫鲨 Scyliorhinus canicula 大脑组织的个体发育变化和性别二态性

在这项研究中，我们调查了小斑猫鲨大脑鳞屑的个体发育和性变化，以及六个主要脑区的鳞屑和相对大小。尖嘴鲛来自地中海。脑体细胞指数（0.31-1.25%）在两性之间没有显着差异，但受到尺寸的显着影响，较小的标本表现出较高的值。大脑生长呈现负异速生长（异速生长系数 0.634），不受性别或成熟度状态的影响。与之前的大西洋研究相比，发现大脑的生长速度更高。关于大脑区域的缩放，嗅球以正向异速生长进行缩放，端脑和间脑以相同的负向异速生长率进行缩放，中脑表现出更高的负向异速生长，而小脑和延髓均遵循紧密-等距增长模式。不成熟S. canicula具有较大的中脑和间脑，突出了视觉在这一生命时期的重要性，而成熟的标本具有扩大的嗅球，表明在动物达到性成熟后嗅觉可能更重要。在两性异形方面，男性有较大的小脑和延髓，而女性有较大的端脑和嗅球。