Ray development
C. elegans male tail contains four types of male-specific sensilla, the most prominent of which are the rays. These 18 sensory rays convey mechano- and chemosensory information critical to male mating. Each ray is composed of three cells: RnA: A-type sensory neuron; RnB: B-type sensory neuron; and Rnst: ray structural cell, which are derived from one neuroblast, the ray precursor cell called Rn. Each ray is morphologically and molecularly distinct from each other. Most all ray identity follows a determinate cell lineage model where cell identity is established based on the pattern of cell division; ray 5 does require external cues from a TGF-beta signalling pathway to adopt its final fate.
Mechanosensation
Mechanosensation converts mechanical energy into electrical signals allowing an organism to use physical cues from the environment or from internal sensors to affect its behavior. Mechanical stimuli are received through mechanosensory receptor neurons (MRNs). In C. elegans, there are 30 putative MRNs in hermaphrodites while an additional 52 MRNs are found in males. More than 40 of these male-specific MRNs are found in the male tail, hook, post-cloacal sensilla and spicule and are required for male mating. MRNs transmit electrical signals to other neurons through electrical or chemical synapses. MRNs may or may not have ciliated dendrite endings, which is some cases are exposed to the outside. Mechanical stimuli initiate as well as modulate many behaviors of the worm. MRNs allow the worm to respond to light touch, such as stroking with an eyelash as well as harsh touch, such as prodding with a pick.