Which tissue type is described as appearing to have multiple layers due to nuclei at different heights, though all cells contact the basement membrane?

Which tissue type is described as appearing to have multiple layers due to nuclei at different heights, though all cells contact the basement membrane?

• A. Pseudostratified epithelium
• B. Simple columnar
• C. Simple squamous
• D. Transitions

Answer: (A)

This item tests how layering can be a visual illusion in epithelial tissue. The described pattern—nuclei at different heights giving a multi-layered look while every cell actually contacts the basement membrane—is characteristic of pseudostratified epithelium. In this tissue, most cells are tall and columnar, but some are shorter and don’t reach the surface, so the nuclei sit at various levels. Because every cell rests on the basement membrane, it’s truly a single layer of cells; it just looks multi-layered under the microscope. A classic example is the ciliated pseudostratified columnar epithelium lining the respiratory tract, where goblet cells produce mucus and cilia help move it along. The other options don’t fit this pattern: simple columnar epithelium is a true single layer of tall cells; simple squamous is a single, flat layer; transitional epithelium can appear multi-layered and changes shape as it stretches, but the key feature described here is the nuclei-at-different-heights illusion while all cells still contact the basement membrane, which points to pseudostratified epithelium.

This item tests how layering can be a visual illusion in epithelial tissue. The described pattern—nuclei at different heights giving a multi-layered look while every cell actually contacts the basement membrane—is characteristic of pseudostratified epithelium. In this tissue, most cells are tall and columnar, but some are shorter and don’t reach the surface, so the nuclei sit at various levels. Because every cell rests on the basement membrane, it’s truly a single layer of cells; it just looks multi-layered under the microscope. A classic example is the ciliated pseudostratified columnar epithelium lining the respiratory tract, where goblet cells produce mucus and cilia help move it along.

The other options don’t fit this pattern: simple columnar epithelium is a true single layer of tall cells; simple squamous is a single, flat layer; transitional epithelium can appear multi-layered and changes shape as it stretches, but the key feature described here is the nuclei-at-different-heights illusion while all cells still contact the basement membrane, which points to pseudostratified epithelium.