McLaughlin B J
J Comp Neurol. 1976 Dec 1;170(3):347-64. doi: 10.1002/cne.901700306.
Photoreceptor synaptogenesis in the embryonic and hatchling chick retina was studied with conventional EM techniques and ethanolic phosphotungstic acid (E-PTA). The photoreceptors line up between 11 and 13 embryonic days with their undifferentiated synaptic bases facing the outer plexiform layer (OPL). E-PTA staining at 11 embryonic days does not reveal any para-membranous specializations of the receptors but numerous stained punctae adhaerentes are observed in the OPL. At 13 embryonic days neurites of presumed bipolar and horizontal neurons are aligned parallel to the bases of the receptors and cytoplasmic protrusions of the receptors project between some of these neurites to form dyad appositions. An osmiophilic undercoating, which is not E-PTA positive at this time, is present on the cytoplasmic face of the receptor membrane in these apposition regions. Between 13 and 15 embryonic days the filopodial protrusions of the receptors continue to elongate further and become aligned with neurites in dyad and triad appositions. The osmiophilic undercoating now extends along the entire inner surface of the receptor pedicle protrusions and becomes E-PTA positive. Between 15 and 17 embryonic days focal aggregations of osmiophilic and E-PTA stained material appear along the membranes of the protrusions and there is some E-PTA staining of the postsynaptic densities and intervening cleft material. Between 17 and 21 embryonic days mature ribbon synapses are observed on the surfaces of the conical-shaped, receptor pedicles where the ribbons and their synaptic vesicles are associated with the dense aggregations (arciform densities), seen earlier as isolated focal aggregations, and the receptor undercoating is restricted to non-synaptic regions. E-PTA staining shows that ribbons are positively stained around their borders only and that they are contiguous with the intensely stained arciform densities. The cleft material and postsynaptic densities of some synapses first stain as V-shaped junctions and later as Y-shaped junctions. These observations suggest that ribbon synaptic junction formation begins with an alignment of pre- and postsynaptic membranes and the presence of the receptor presynaptic membrane undercoating, followed by the appearance of the presynaptic arciform densities and some staining of the cleft material and postsynaptic densities. These events are followed by the appearance of synaptic ribbons which are associated with the presynaptic arciform densities and by a further differentiation of the cleft material and postsynaptic densities.
利用传统电子显微镜技术和乙醇磷钨酸（E-PTA）对胚胎期和刚孵出雏鸡视网膜中的光感受器突触形成进行了研究。在胚胎期11至13天，光感受器排列成行，其未分化的突触基部朝向外网状层（OPL）。胚胎期11天时，E-PTA染色未显示感受器有任何膜旁特化，但在OPL中观察到大量染色的粘着斑。在胚胎期13天时，推测的双极神经元和水平神经元的神经突与感受器基部平行排列，感受器的细胞质突起在其中一些神经突之间伸出，形成二元并置。在这些并置区域的感受器膜的细胞质面上存在一种嗜锇性底层，此时它对E-PTA呈阴性。在胚胎期13至15天之间，感受器的丝状突起继续进一步伸长，并在二元和三元并置中与神经突对齐。嗜锇性底层现在沿着感受器柄状突起的整个内表面延伸，并变为E-PTA阳性。在胚胎期15至17天之间，嗜锇性和E-PTA染色物质的局灶性聚集出现在突起的膜上，并且突触后致密物和中间缝隙物质有一些E-PTA染色。在胚胎期17至21天之间，在圆锥形的感受器柄状突起表面观察到成熟的带状突触，其中带状物及其突触小泡与致密聚集物（弧形致密物）相关联，早期表现为孤立的局灶性聚集，并且感受器底层仅限于非突触区域。E-PTA染色显示，带状物仅在其边界周围呈阳性染色，并且它们与强烈染色的弧形致密物相邻。一些突触的缝隙物质和突触后致密物首先染为V形连接，然后染为Y形连接。这些观察结果表明，带状突触连接的形成始于突触前膜和突触后膜的对齐以及感受器突触前膜底层的存在，随后是突触前弧形致密物的出现以及缝隙物质和突触后致密物的一些染色。这些事件之后是与突触前弧形致密物相关的突触带状物的出现以及缝隙物质和突触后致密物的进一步分化。
