Pineal complex of the clawed toad, Xenopus laevis Daud.: Structure and function
Pineal complex of the clawed toad, Xenopus laevis Daud.: Structure and function
复制标题
爪蟾 (Xenopus laevis Daud.) 的松果体复合体：结构和功能
DOI：
10.1007/bf00234548
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发表时间：
2004
影响因子：
3.6
通讯作者：
A. Kirk
中科院分区：
文献类型：
--
作者：
H. Korf;R. Liesner;H. Meissl;A. Kirk
对非洲爪哇幼虫、幼虫和成年动物松果体复合体的形态和生理特性进行了研究。Levis，额叶器官没有退化的迹象。完全分化的额叶器官含有典型的低等脊椎动物松果体复合体的光感受器。用乙酰胆碱酯酶(AChE)反应，在额叶器官显示了约30个两种不同类型的神经元。额叶器官神经由大约10根有髓神经纤维和40根无髓神经纤维组成。额叶器官的神经纤维区一般类似于颅内骨骺的相应结构。X。大脑骨骺的神经器官。Levis由(1)光感受器细胞，(2)∼-100 AChE阳性神经元，(3)复合神经纤维区和(4)由∼-10有髓神经纤维和∼-100无髓神经纤维组成的松果体束组成。它们中的一些显示出颗粒状包裹体，表明松果体顶叶元素可能进入松果体复合体X。通过这条路径。松果体束的地形图。Levis与脊椎动物有很大的不同。丛状带最明显的成分是带状突触。光感受器细胞的基本突起可能是简单突触、切向突触、二联突触或三联突触的突触前成分。常规突触只是偶尔观察到，电生理记录显示非洲爪哇的松果体复合体对光直接敏感。在对光刺激的反应中，从额叶器官的神经记录到两种类型的反应，即无色反应和有色反应。相反，骨痂只显示了无色的单位。显色反应的相反颜色机制显示出最大的敏感性，抑制事件在360 nm左右，兴奋事件在520 nm左右。骨骺和额叶的消色反应的作用光谱在500~520 nm之间达到峰值，在暗适应过程中没有浦肯野漂移。讨论了这些现象的功能意义。
The morphological and physiological properties of the pineal complex ofXenopus laeviswere investigated in larval, juvenile and adult animals.In a representative majority of adultX. laevis, the frontal organ does not display signs of degeneration. Fully differentiated frontal organs contain photoreceptors typical of the pineal complex of lower vertebrates. By means of the acetylcholinesterase (AChE)-reaction approximately 30 neurons of two different types were demonstrated in the frontal organ. The frontal-organ nerve is composed of approximately 10 myelinated and 40 unmyelinated nerve fibers. The neuropil areas of the frontal organ are generally similar to the corresponding structures of the intracranial epiphysis.The neuronal apparatus of the epiphysis cerebri ofX. laevisconsists of (i) photoreceptor cells, (ii) ∼100 AChE-positive neurons, (iii) complex neuropil areas, and (iv) a pineal tract formed by ∼10 myelinated and ∼100 unmyelinated nerve fibers. Some of them exhibit granular inclusions indicating that pinealopetal elements may enter the pineal complex ofX. laevisvia this pathway. The topography of the pineal tract ofX. laevisdiffers considerably from that in ranid species. The most conspicuous element of the plexiform zones is the ribbon synapse. The basal processes of the photoreceptor cells may be presynaptic elements of simple, tangential, dyad or triad synaptic contacts. Conventional synapses were observed only occasionally.Electrophysiological recordings revealed that the pineal complex ofXenopus laevisis directly sensitive to light. In response to light stimuli, two types of responses, achromatic and chromatic, were recorded from the nerve of the frontal organ. In contrast, the epiphysis exhibited only achromatic units. The opposed color mechanism of the chromatic response showed a maximum sensitivity at approximately 360 nm for the inhibitory and at 520 nm for the excitatory event. The action spectrum of the achromatic response of the epiphysis and the frontal organ peaked between 500 and 520 nm and showed no Purkinje-shift during dark adaptation. The functional significance of these phenomena is discussed.