Ditmann Frank, Ehni Rainer, Engels Wolf
Institut für Biologie III, (Zoologie/Entwicklungsphysiologie) der Universität Tübingen, Auf der Morgenstelle 28, D-7400, Tübingen, Germany.
Wilehm Roux Arch Dev Biol. 1981 Jul;190(4):221-225. doi: 10.1007/BF00848306.
Two systems of steady extra-cellular currents were found along the surface of the telotrophicDysdercus ovarioles by means of a vibrating probe. The first covers the subgerminal tropharium and all the previtellogenic follicles. The current leaves the 3 or 4 small follicles of early euplasmic growth stages laterally and enters the syncytial tropharium. We presume that a similar intracellular current flows between the trophoplasm and the ooplasm which are interconnected by narrow nurse strands. Preliminary intracellular measurements indicate a potential gradient within this continuous cytoplasm, the ooplasm being electropositive to that of the tropharium. This current system fits into a model of polarized intracytoplasmic transport by electrophoresis. It is possible to explain the well known directed and selective flow of RNA from the tropharium via the nurse strands into the oocytes by means of such a model. The second current system occurs around every one of the 2 to 8 vitellogenic follicles. The pattern is completely different from that described for the first system. In the vitellogenic stages the current enters the follicle laterally all along the now much extended surface. It is balanced by a strong peak current which leaves the interfollicular region. As data on intracellular currents are not yet avialable, it is only a matter of speculation whether the circuit is closed through the ooplasm or only by a tangential loop through the follicle epithelium. The possible significance of this second current system for vitellogenin accumulation and uptake by the vitellogenic oocytes is also uncertain as yet.
通过振动探针，在端滋式红蝽卵巢管表面发现了两个稳定的细胞外电流系统。第一个系统覆盖胚下营养区和所有卵黄发生前的卵泡。电流从早期质优生长阶段的3或4个小卵泡侧向流出，进入合胞体营养区。我们推测，类似的细胞内电流在通过狭窄的滋养丝相互连接的滋养质和卵质之间流动。初步的细胞内测量表明，在这种连续的细胞质内存在电位梯度，卵质相对于营养区呈电正性。这个电流系统符合电泳介导的极化胞质内运输模型。通过这样一个模型，可以解释众所周知的RNA从营养区通过滋养丝向卵母细胞的定向和选择性流动。第二个电流系统出现在2至8个卵黄发生卵泡中的每一个周围。其模式与第一个系统所描述的完全不同。在卵黄发生阶段，电流沿着现在大大扩展的表面从侧面进入卵泡。它由离开卵泡间区域的强峰值电流平衡。由于尚未获得细胞内电流的数据，电路是通过卵质闭合还是仅通过卵泡上皮的切向环闭合，这只是一个猜测的问题。第二个电流系统对于卵黄发生卵母细胞积累和摄取卵黄蛋白原的可能意义目前也尚不确定。
