Putative Sensory Neurons Research Articles

Expression of the egg-laying hormone genes in peripheral neurons and exocrine cells in the reproductive tract of the mollusc Lymnaea stagnalis

The neuroendocrine caudodorsal cells play an important role in the control of reproduction in Lyrmaea stagnalis. These neurons produce at least nine neuropeptides which are encoded by caudodorsal cell hormone-I and -II genes. The role of some of these peptides in the control of reproduction has been established. The present study demonstrates that the transcription and translation of the caudodorsal cell hormone genes also proceeds abundantly in the reproductive tract of this hermaphroditic animal. In the female part of the reproductive tract neurons were found to express gene I. These neurons are most likely involved in the control of transport of the eggs and egg-masses and in the regulation of secretory activity from the female accessory sex glands. In the male part of the reproductive tract exocrine secretory cells express gene I or gene II. The gene products are secreted into the male duct and transferred to the female copulant during copulation. Furthermore, putative sensory neurons in the skin were found to express gene I. The results indicate that in L. stagnalis the complex process of reproduction is regulated—at least in part—by a set of neuropeptides which are encoded by a small multigene family, viz. the caudodorsal cell gene family.

Morphology and function of the support cell and the nerve tracts innervating the presoma of Moniliformis moniliformis (Acanthocephala)

The nerve tracts emerging from the cerebral ganglion of Moniliformis moniliformis were examined using electron microscopy. Nerve cells in the cerebral ganglion Moniliformis moniliformis send their processes into the nerve tracts. Type A, B, and D neurons contributed their processes to the nerves innervating putative sensory structures located on the neck and tip of the proboscis, and were classified as putative sensory neurons. Large numbers of electron-dense vesicles observed in the type A and B axons were correlated with the presence of the catecholamine dopamine. Type C neurons were seen to innervate receptacle wall muscles. The presence of neuromuscular-type junctions, with round, clear vesicles near presynaptic membranes, was observed. The type C neurons were therefore classified as putative motor neurons. Type E processes did not contribute to the nerve tracts.