The external limiting membrane (ELM) is a true membrane.

The external limiting membrane (ELM) is a true membrane.

• A. True
• B. False
• C. Acellular
• D. Located in the iris

Answer: (B)

The external limiting membrane is not a true membrane. It’s a boundary formed by junctions between photoreceptor inner segments and Müller glial cell processes, specifically adherens and tight junctions, rather than a separate lipid bilayer–based membrane. This junctional layer sits at the border of the outer nuclear layer and the photoreceptor inner segments in the retina, helping to stabilize the retinal architecture and regulate diffusion between retinal layers. It is not located in the iris, and it is not acellular, since it involves cellular junctions from retinal cells. So the statement is false because the ELM is a junctional boundary, not a true membranous structure.

The external limiting membrane is not a true membrane. It’s a boundary formed by junctions between photoreceptor inner segments and Müller glial cell processes, specifically adherens and tight junctions, rather than a separate lipid bilayer–based membrane. This junctional layer sits at the border of the outer nuclear layer and the photoreceptor inner segments in the retina, helping to stabilize the retinal architecture and regulate diffusion between retinal layers. It is not located in the iris, and it is not acellular, since it involves cellular junctions from retinal cells. So the statement is false because the ELM is a junctional boundary, not a true membranous structure.