Somatostatin-28-like immunoreactivity in the rat olfactory bulb.

Using an immunoperoxidase technique, somatostatin-28-like immunoreactive (LIR) neurons were observed in the main and accessory olfactory bulb (MOB and AOB) of adult rats. In the MOB, a restricted population of periglomerular cells in the glomerular layer, some superficial short-axon cells in the juxtaglomerular layer, and some deep short-axon cells in the granule cell layer were IR. The periglomerular and the superficial short-axon cells were stained so well that they looked like Golgi-impregnated specimens. In the AOB, a very small population of small neurons in the glomerular layer, a very few medium-sized and large neurons in the external plexiform layer, and some neurons in the granule cell layer, which seem to be corresponding to the deep short-axon cells in the MOB, were IR. The present results have revealed that different morphological types of bulbar neurons are somatostatin-28-LIR; they also indicate neurochemical differences between the MOB and AOB.