Photoreceptor Inner Segment (Myoid Layer) forms which part?

Photoreceptor Inner Segment (Myoid Layer) forms which part?

• A. Proximal part of inner segment near the cell body
• B. Distal part of outer segment
• C. Axons of retina
• D. Outer limiting Membrane

Answer: (A)

The part closest to the cell body of a photoreceptor’s inner segment is formed by the myoid layer. This proximal portion houses organelles like the rough endoplasmic reticulum and Golgi apparatus, which are engaged in synthesizing and assembling proteins and membrane components that will be needed by the outer segment. In other words, the myoid supplies and builds the initial components for the inner segment itself and for delivery toward the outer segment. For context, the inner segment has a distal portion called the ellipsoid, rich in mitochondria and providing energy for the cell, while the outer segment houses the light-detecting visual pigments in its stacked discs. The outer limiting membrane is a separate boundary at the junction between photoreceptors and Müller glial cells, and the axons of the retina reside in the nerve fiber layer, not in the inner segment.

The part closest to the cell body of a photoreceptor’s inner segment is formed by the myoid layer. This proximal portion houses organelles like the rough endoplasmic reticulum and Golgi apparatus, which are engaged in synthesizing and assembling proteins and membrane components that will be needed by the outer segment. In other words, the myoid supplies and builds the initial components for the inner segment itself and for delivery toward the outer segment.

For context, the inner segment has a distal portion called the ellipsoid, rich in mitochondria and providing energy for the cell, while the outer segment houses the light-detecting visual pigments in its stacked discs. The outer limiting membrane is a separate boundary at the junction between photoreceptors and Müller glial cells, and the axons of the retina reside in the nerve fiber layer, not in the inner segment.