Ultrastructure, number, distribution and innervation of electroreceptors and mechanoreceptors in the bill skin of the platypus, Ornithorhynchus anatinus
Ultrastructure, number, distribution and innervation of electroreceptors and mechanoreceptors in the bill skin of the platypus, Ornithorhynchus anatinus
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DOI：
10.1159/000113185
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发表时间：
1996-07-01
影响因子：
1.7
通讯作者：
Pettigrew, JD
中科院分区：
文献类型：
--
作者：
Manger, PR;Pettigrew, JD
鸭嘴兽是目前唯一被证明使用电感受来获取食物的哺乳动物。鸭嘴兽的电感受系统远比它的近亲针鼹鼠复杂。本文对鸭嘴兽的电感受基础进行了解剖学研究。描述了三叉神经对喙的神经支配，以及喙皮肤内与食物收集有关的三个感觉结构。在鸭嘴兽的嘴皮中发现了40,000个粘液腺电感受器。这些感觉粘液腺的乳头状部分被修饰以容纳电感觉神经末梢。与鱼类的电感受器不同，鸭嘴兽的电感受器末梢不与感觉细胞相连。这些粘液腺电感受器在喙上排列成一系列的旁腺条纹。这一阵列表明了鸭嘴兽快速准确地定位电刺激来源的能力的基础。一个推杆机械感受器，在形态上类似于鼹鼠的艾默器官和鸟类的喙尖器官，也被发现在票据皮肤。这些机械感受器与鸟类和talpid对应物相比，形态略有不同，这表明这是趋同进化的另一个例子，共同需要提供一种解决方案，以增加裸露皮肤上的触觉敏感性。这些推杆被发现是最密集的唇缘周围的法案，与密度显着下降，向中间和尾部的部分法案。推杆的分布与喙上的第三种感觉结构（感觉浆液腺）的分布相似。虽然数量少于机械感受器（46，500个机械感受器与13，500个感觉浆液腺相比），但这些感觉浆液腺具有相似的分布和相似的密度变化。这些并发分布论证了这两种感觉结构的某些功能相关性。浆液腺的乳头区以类似于粘液腺电感受器的方式被修饰以适应感觉输入。浆液腺的感觉末梢与粘液腺电感受器的感觉末梢非常相似，因此推测这些感觉浆液腺是一种电感受器，可能参与机械感受器也参与的近距离电信号检测。
The platypus is presently the only mammal demonstrated to use electroreception to obtain food. The electroreceptive system of the platypus is far more complex than that of its close relative the echidna. This paper presents an anatomical study of the basis of electroreception in the platypus. The innervation of the bill by the trigeminal nerve is described, as are three sensory structures, associated with food gathering, within the bill skin. There are 40,000 mucous gland electroreceptors found in the bill skin of the platypus. The papillary portion of each of these sensory mucous glands is modified to accommodate electrosensory nerve terminals. In contrast to fish electroreceptors, the electrosensory terminals of the platypus are not associated with a sensory cell. These mucous gland electroreceptors are arranged in a series of parasagittal stripes on the bill. This array suggests a basis for the ability of the platypus to quickly and accurately locate the origin of an electrical stimulus. A push-rod mechanoreceptor, similar in morphology to Eimer's organ of the mole, and bill-tip organs in birds, was also found in the bill skin. The slightly differing morphology of these mechanoreceptors when compared to their avian and talpid counterparts suggests that this is another example of convergent evolution, with the common need to provide a solution to increasing tactile sensitivity on bare rhinarial skin. These push-rods are found to be most dense around the labial margins of the bill, with a marked decrease in density towards the middle and caudal portions of the bill. The distribution of the push-rods is similar to the distribution of the third sensory structure found on the bill, the sensory serous gland. Although less numerous than the mechanoreceptors (46,500 mechanoreceptors compared with 13,500 sensory serous glands), these sensory serous glands have a similar distribution and similar changes in density. These concurrent distributions argue for some functional correlation of these two sensory structures. The papillary region of the serous gland is modified in a manner similar to that of the mucous gland electroreceptor to accommodate sensory input. The sensory terminals of the serous glands are very similar to those of the mucous gland electroreceptors, and so it is presumed that these sensory serous glands are a type of electroreceptor that might be involved in detection of electrical signals at close quarters where the mechanoreceptors are also engaged.