Target tissues affect cellular properties of cocultured leech Retzius neurons

The development of many neurons, including the Retzius (Rz) neurons of the medicinal leech, is shaped in part by interactions with other cells in the environment. To explore the nature of the interaction between growing Rz processes and potential target tissues, adult Rz neurons were cultured directly in contact with some of the tissues that normally serve as their targets in vivo. The morphology of the regenerated processes of these neurons varied depending upon the identity of the target tissues, but other cellular properties remained unchanged. In particular, although during normal development contact with peripheral targets determines the sign of Rz neurons' response to acetylcholine (ACh) applied to the soma, these cultured neurons maintained their original response to ACh even after as long as 2 weeks in culture on novel targets. Hence, some features of cultured adult Rz neurons varied depending upon the conditions, whereas other features remained fixed.