Which part of the photoreceptor contains the nucleus?

• A. Outer segment
• B. Cell body
• C. Inner segment
• D. Synaptic terminal

Answer: (C)

In a photoreceptor, the nucleus is housed in the cell body, or soma. The cell body sits between the inner segment and the outer segment. The outer segment is where light detection happens with stacked photopigment discs, while the inner segment contains the cell’s metabolic machinery, including mitochondria. The synaptic terminal at the base communicates with bipolar and horizontal cells. Because the nucleus is part of the main cellular body that houses genetic material and directs cell function, it resides in the cell body rather than in the outer segment or synaptic terminal. In retinal histology, photoreceptor nuclei are located in the outer nuclear layer.