Which cellular component inside the retinal pigment epithelium is crucial for phagocytosis of photoreceptor outer segments?

Which cellular component inside the retinal pigment epithelium is crucial for phagocytosis of photoreceptor outer segments?

• A. Hyalocytes
• B. Keratocytes
• C. Lysosomes
• D. Eosinophils

Answer: (C)

Lysosomes within the retinal pigment epithelium perform the digestion that enables phagocytosis of photoreceptor outer segments. The RPE continually engulfs shed outer segment discs from rods and cones; these phagosomes then fuse with lysosomes, where hydrolytic enzymes break down the disc membranes and proteins. This recycling is essential for photoreceptor maintenance and prevents buildup of waste that could impair vision. Other cells listed aren’t located in the RPE or tasked with this turnover—hyalocytes reside in the vitreous, keratocytes in the corneal stroma, and eosinophils are immune cells not responsible for POS digestion in the RPE.

Lysosomes within the retinal pigment epithelium perform the digestion that enables phagocytosis of photoreceptor outer segments. The RPE continually engulfs shed outer segment discs from rods and cones; these phagosomes then fuse with lysosomes, where hydrolytic enzymes break down the disc membranes and proteins. This recycling is essential for photoreceptor maintenance and prevents buildup of waste that could impair vision. Other cells listed aren’t located in the RPE or tasked with this turnover—hyalocytes reside in the vitreous, keratocytes in the corneal stroma, and eosinophils are immune cells not responsible for POS digestion in the RPE.