Carter Richard T
University of Dayton, Dayton, OH, USA.
J Anat. 2017 Apr;230(4):589-595. doi: 10.1111/joa.12575. Epub 2016 Dec 29.
The production of echolocation calls in bats along with forces produced by contraction of thoracic musculature used in flight presumably puts relatively high mechanical loads on the lower respiratory tract (LRT). Thus, there are likely adaptations to prevent collapse or distortion of the bronchial tree and trachea during flight in echolocating bats. By clearing and staining (Alcian blue and Alizarin red) LRTs removed from nonvolant neonates, semivolant juveniles, volant subadults, and adult Jamaican fruit bats (Artibeus jamaicensis), I found that calcification of the tracheal, primary bronchial, and secondary bronchial (lobar) cartilage rings occurs over the span of about 3 days and coincides with later developmental stages of flight and the increased production of echolocation calls. Tracheal rings that are immediately adjacent to the larynx calcified first, followed by more caudal tracheal rings and then the rings of the primary and secondary bronchi. I suggest that calcification of LRT cartilage rings in echolocating bats provides increased rigidity to counter the thoracic compressions incurred during flight. Calcification of the LRT rings is an adaptation to support the emission of laryngeally produced echolocation calls during flight in bats.
蝙蝠发出回声定位叫声，同时飞行时胸部肌肉收缩产生的力量可能会给下呼吸道（LRT）带来相对较高的机械负荷。因此，在回声定位蝙蝠飞行过程中，可能存在一些适应性变化来防止支气管树和气管塌陷或变形。通过对从不会飞的幼崽、半会飞的幼体、会飞的亚成体以及成年牙买加果蝠（Artibeus jamaicensis）身上取下的下呼吸道进行清理和染色（阿尔新蓝和茜素红），我发现气管、初级支气管和次级支气管（叶支气管）软骨环的钙化在大约3天内完成，并且与飞行的后期发育阶段以及回声定位叫声的增加产生时间相吻合。紧邻喉部的气管环首先钙化，随后是更靠后的气管环，然后是初级和次级支气管的环。我认为，回声定位蝙蝠下呼吸道软骨环的钙化增加了其硬度，以应对飞行过程中胸部受到的挤压。下呼吸道环的钙化是一种适应性变化，以支持蝙蝠在飞行过程中发出由喉部产生的回声定位叫声。
