Final answer:
The reticular dermal layer is not a sensory receptor, unlike Merkel discs, nociceptors, and Pacinian corpuscles, which all respond to various tactile stimuli in the skin.
Step-by-step explanation:
The sensory receptors in the skin that are not actual receptors are the reticular dermal layer. The other options listed - Merkel discs, nociceptors, and Pacinian corpuscles - are all specialized sensory receptors that respond to various tactile stimuli. Merkel discs are unencapsulated and respond to light touch, often found on fingertips and lips. Nociceptors are free nerve endings that generally respond to pain. Pacinian corpuscles are encapsulated and rapidly adapting receptors that detect transient pressure and high-frequency vibration and are present in both glabrous and hairy skin. In contrast, the reticular dermal layer is not a sensory receptor; it is a layer of the skin that provides support and elasticity.