Eldred W D, Nolte J
J Comp Neurol. 1981 Dec 1;203(2):269-95. doi: 10.1002/cne.902030208.
An attempt has been made to characterize the photoreceptors and neurons of the frontal organ of Rana pipiens and the synaptic contacts of these cells, in order to provide morphological correlates for previous physiological findings. Neurons, glial cells, and photoreceptors with two different appearances can be seen in normal anatomical preparations. The photoreceptors make ribbon synaptic contacts onto both neurons and other photoreceptors. Retrograde transport of either cobalt or horseradish peroxidase through the frontal nerve results in labeling of neurons which are often located near the exit point of the frontal nerve from the frontal organ. Some of the dendritic processes of these neurons ramify among the neurons themselves, while others ramify among the photoreceptors. In addition, the frontal organ contains two photoreceptor types which synaptically contact both neurons and other photoreceptors. In some frontal organs labeled with cobalt (but never in peroxidase-labeled preparations) certain photoreceptors were also labeled. The labeled photoreceptors were probably the result of transcellular cobalt movement from labeled neurons, and not the result of some photoreceptors having axons in the frontal nerve. These results are discussed in conjunction with physiological evidence that chromatic interactions occur within single photoreceptors, each of which contains a single visual pigment with two physiologically active states.
为了为之前的生理学发现提供形态学关联，人们尝试对牛蛙额器官的光感受器、神经元及其细胞间的突触联系进行表征。在正常解剖标本中可以看到神经元、神经胶质细胞以及两种外观不同的光感受器。光感受器与神经元和其他光感受器均形成带状突触联系。通过额神经逆行运输钴或辣根过氧化物酶，会使通常位于额神经从额器官穿出点附近的神经元被标记。这些神经元的一些树突分支在神经元之间，而其他的则在光感受器之间分支。此外，额器官包含两种光感受器类型，它们与神经元和其他光感受器均形成突触联系。在一些用钴标记的额器官中（但在过氧化物酶标记的标本中从未出现），某些光感受器也被标记。这些被标记的光感受器可能是钴从标记神经元进行跨细胞移动的结果，而非一些光感受器在额神经中有轴突的结果。结合生理学证据对这些结果进行了讨论，生理学证据表明在单个光感受器内发生颜色相互作用，每个光感受器都包含一种具有两种生理活性状态的单一视觉色素。
