Giannessi F, Ruffoli R
Istituto di Anatomia Normale, Universita degli Studi di Pisa, Italy.
Ann Anat. 1996 Apr;178(2):127-31. doi: 10.1016/S0940-9602(96)80027-6.
The afferent synapses of the paratympanic organ in the chicken were studied by TEM. These synapses were formed by non-myelinated fibres which reached the basal part of the hair cells. The fibres contained a number of irregular mitochondria and a few pale vesicles. In the hair cells, near the presynaptic membrane, typical synaptic bodies formed by an electron-dense core surrounded by several small pale vesicles were present. The core was connected with the vesicles by numerous thin filaments, and at same time with the presynaptic membrane by some dense projections. Moreover, we have observed that the connections between the core and the adjacent vesicles also consisted of similar structures to the dense projections. We suggest that this device is involved in the movement of the vesicles towards the presynaptic membrane. Our hypothesis is in agreement with that formulated by some authors who believe that the electron-dense core of the synaptic bodies is able to channel the vesicles to the presynaptic membrane (conveyor-belt hypothesis). Moreover, our work showed that the synaptic bodies of the paratympanic organ in the chicken are variable in density and in shape. These morphological aspects might be linked to regression-reconstitution cycles of the SBs and to the functional level of the afferent synapses.
利用透射电子显微镜（TEM）对鸡鼓室旁器官的传入突触进行了研究。这些突触由到达毛细胞基部的无髓纤维形成。纤维含有许多不规则的线粒体和一些浅色小泡。在毛细胞中，靠近突触前膜处，存在由电子致密核心和几个小浅色小泡围绕形成的典型突触小体。核心通过许多细丝与小泡相连，同时通过一些致密突起与突触前膜相连。此外，我们观察到核心与相邻小泡之间的连接也由与致密突起相似的结构组成。我们认为这种结构参与了小泡向突触前膜的移动。我们的假设与一些作者提出的观点一致，他们认为突触小体的电子致密核心能够将小泡引导至突触前膜（传送带假说）。此外，我们的研究表明，鸡鼓室旁器官的突触小体在密度和形状上是可变的。这些形态学特征可能与突触小体的退化-重建周期以及传入突触的功能水平有关。
