The formation and dissolution of the bridge-partitioning complex in intercellular bridges of dividing germ cells in the testis of the golden hamster

Intercellular bridges (IBs) connecting mammalian germ cells get transiently closed during cell divisions by a structure termed the bridge-partitioning complex (BPC). It is composed of a compact stack of transverse endomembrane cisterns that are laterally anchored to the thickened bridge wall (bridge density). Studying male gonads of the golden hamster, the formation of the BPC during prophase/prometaphase transition and its dissolution in late telophase of germ cell divisions was followed. 1) There are strong indications for the involvement of a microtubule-based transport mechanism in the movement of membrane-bound vesicles toward and away from the site of the BPC during its formation or dissolution, respectively. 2) The BPC is built up exactly within the central segment of the IB carrying the bridge density. This feature suggests a specific interaction between components of the (forming) BPC and the material constituting the bridge density. The bridge density might be involved in locally directing the process of BPC formation within germ cell IBs.