Schulz Andrew K, Kaufmann Lena V, Reveyaz Noemie, Ritter Cindy, Hildebrandt Thomas, Brecht Michael
Haptic Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany.
Bernstein Center for Computational Neuroscience Berlin, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 6, Berlin 10115, Germany.
R Soc Open Sci. 2024 Oct 9;11(10):240851. doi: 10.1098/rsos.240851. eCollection 2024 Oct.
The trunks of elephants have prominent wrinkles from their base to the very tip. But neither the obvious differences in wrinkles between elephant species nor their development have been studied before. In this work, we characterize the lifelong development of trunk wrinkles in Asian and African elephants. Asian elephants have more dorsal major, meaning deep and wide, trunk wrinkles (approx. 126 ± 25 s.d.) than African elephants (approx. 83 ± 13 s.d.). Both species have more dorsal than ventral major trunk wrinkles and a closer wrinkle spacing distally than proximally. In Asian elephants, wrinkle density is high in the 'trunk wrapping zone'. Wrinkle numbers on the left and right sides of the distal trunk differed as a function of trunk lateralization, with frequent bending in one direction causing wrinkle formation. Micro-computed tomography (microCT) imaging and microscopy of newborn elephants' trunks revealed a constant thickness of the putative epidermis, whereas the putative dermis shrinks in the wrinkle troughs. During fetal development, wrinkle numbers double every 20 days in an early exponential phase. Later wrinkles are added slowly, but at a faster rate in Asian than African elephants. We discuss the relationship of species differences in trunk wrinkle distribution and number with behavioural, environmental and biomechanical factors.
大象的象鼻从根部到顶端都有明显的皱纹。但此前从未对大象物种之间皱纹的明显差异及其发育情况进行过研究。在这项研究中，我们描述了亚洲象和非洲象象鼻皱纹的终生发育情况。亚洲象的背部主要皱纹，即又深又宽的皱纹（约126±25标准差）比非洲象（约83±13标准差）更多。两种大象的背部主要象鼻皱纹都比腹部多，且远端的皱纹间距比近端更近。在亚洲象中，“象鼻缠绕区域”的皱纹密度很高。象鼻远端左右两侧的皱纹数量因象鼻的侧向化而有所不同，频繁向一个方向弯曲会导致皱纹形成。对新生象鼻进行的微型计算机断层扫描（microCT）成像和显微镜检查显示，假定的表皮厚度恒定，而假定的真皮在皱纹凹槽处收缩。在胎儿发育过程中，皱纹数量在早期指数阶段每20天增加一倍。后期皱纹增加缓慢，但亚洲象比非洲象增加得更快。我们讨论了象鼻皱纹分布和数量的物种差异与行为、环境和生物力学因素之间的关系。
