any structural anomaly of the pseudostratified columnar epithelium that lines the seminal vesicles and consists of tall, non-ciliated columnar cells and short, rounded basal cells that rest on the basal lamina; polarized columnar cells show features typical of secretory epithelium, including a well-developed Golgi complex, abundant rough endoplasmic reticulum, numerous mitochondria, and apical secretory vesicles; basal cells are the stem cells from which the columnar cells are derived