Pác L
Z Mikrosk Anat Forsch. 1978;92(4):744-52.
The ultrastructure of sensory nerve endings was examined in joint capsules of large limb joints in three adult frogs (Rana temporaria). The joint receptors are represented by the only one kind of sensory nerve endings--by free nerve endings. The unmyelinized preterminal desintegrates into single terminals. This branching is bound on the most peripheral cell of the Schwann cell by means of mesaxons, they pass from the pericaryum of the Schwann cell peripherally. The branches of the nerve terminal are surrounded by a cover of 1...3 cytoplasmatic processes of the Schwann cell. The surface lamella is covered by a distinct basal membrane. Bundles of collagenous fibrils pass along the branches of the nerve terminal. Quite naked nerve endings were not observed. The axoplasma of the nerve terminal contains strikingly few cell organels. Besides axially passing neurofilaments and neurotubules only sporadic mitochondria and clear vesicles were observed. The accumulation of mitochondria, characteristic for the axoplasma of nerve terminals, was observed in no case. Free nerve endings which were found in the joint capsules of the frog belong among so called "free penicillate nerve endings".
对三只成年青蛙（林蛙）四肢大关节关节囊内感觉神经末梢的超微结构进行了检查。关节感受器仅由一种感觉神经末梢——游离神经末梢代表。无髓鞘的终末前纤维解体为单个终末。这种分支通过轴系膜与施万细胞最外周的细胞相连，它们从施万细胞的胞体向外周延伸。神经终末的分支被施万细胞的1至3个细胞质突起覆盖。表面薄片被一层明显的基底膜覆盖。胶原纤维束沿着神经终末分支走行。未观察到完全裸露的神经末梢。神经终末轴浆内细胞器极少。除了沿轴走行的神经丝和神经微管外，仅观察到散在的线粒体和清亮小泡。未观察到神经终末轴浆特有的线粒体聚集现象。在青蛙关节囊内发现的游离神经末梢属于所谓的“游离刷状神经末梢”。
