Several types of mammalian sensory receptor cells possess modified cilia which may play a primary role in stimulus detection. Axonemes and basal apparatus from other types of cilia and flagella have been isolated, characterized and compared in detail. In this communication we report results of what may be the first attempt to isolate and characterize such structures from a sensory cilium, the bovine retinal rod outer segment.

Bovine eyes were obtained from a nearby abattoir, the retinas were removed and swirled vigorously in a cold solution of 50% sucrose, 5 mM Tris, 2 mM MgCl2, pH 7.5, to detach outer segments. The suspension was then filtered through cheesecloth and the filtrate was centrifuged at 20,000 rpm for 1 hr. Rod outer segments were collected from the solution surface, diluted, layered onto a continuous sucrose gradient (25-38% sucrose in Tris MgCl2 buffer) and centrifuged for 3-12 hrs. at 10,000 rpm.