Desaki J
Department of Anatomy, Ehime University School of Medicine, Japan.
Arch Histol Cytol. 1990 Oct;53(4):449-54. doi: 10.1679/aohc.53.449.
The multiaxonal nerve endings, consisting of a bundle of axons, were reexamined in the muscle spindles of the adult Chinese hamster. In addition to the frequent occurrence of the multiaxonal endings innervating the nuclear bag fibers in the equatorial region (Desaki and Uehara, 1988), these endings were also occasionally distributed not only in the equatorial region of the nuclear chain fibers, adjacent to annulospiral sensory endings, but also in the polar region of the same muscle fiber. They were derived from non-myelinated stem nerves becoming varicose along their course. Terminal axons composing the endings were almost naked, except at the initial muscle-contact portion, where they were surrounded by Schwann cell processes. They contained a significant number of clear synaptic vesicles and large granulated vesicles, and were closely apposed to each other and to the muscle cell surface without an interposing basal lamina. Some terminal axons formed synaptic contacts with each other and with the muscle cell surface. These structural features, including their wide distribution, suggest that the multiaxonal endings may belong to the autonomic nerves rather than the fusimotor nerves.
由一束轴突组成的多轴突神经末梢在成年中国仓鼠的肌梭中被重新研究。除了在赤道区域支配核袋纤维的多轴突末梢频繁出现（出木杉和上原，1988年）外，这些末梢偶尔不仅分布在核链纤维的赤道区域，毗邻环螺旋感觉末梢，还分布在同一肌纤维的极区。它们源自无髓鞘的干神经，这些神经在其行程中变得曲张。构成末梢的终末轴突几乎是裸露的，除了在最初与肌肉接触的部分，在那里它们被施万细胞突起包围。它们含有大量清亮的突触小泡和大颗粒小泡，彼此紧密并列并与肌细胞表面紧密相邻，其间没有插入基膜。一些终末轴突相互之间以及与肌细胞表面形成突触接触。这些结构特征，包括它们广泛的分布，表明多轴突末梢可能属于自主神经而非梭内肌运动神经。
