Which process is continuously taking place in the outer segments of photoreceptors?

• A. Discs shedding
• B. Mitosis
• C. Neurotransmitter release
• D. Vesicle formation

Answer: (A)

Photoreceptors keep their outer segments in a state of constant renewal. New discs are formed and pushed toward the base, while old discs are shed from the tip and then engulfed and digested by the retinal pigment epithelium. This ongoing shedding and phagocytosis maintain functional photopigment membranes and remove damaged material caused by light exposure, keeping vision reliable.

Mitosis doesn’t occur in mature photoreceptors, so division isn’t part of what happens there. Neurotransmitter release happens at the synaptic terminals, not in the outer segments. Vesicle formation is a general cellular process and isn’t the specific renewal activity happening in the outer segments. The continuous process in the outer segments is discs shedding.