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HA3 is an EM of the basal portion of an epithelial cell. The nucleus (N) and a few organelles are visible in the cytoplasm. Traversing the lower third of the image is the basement membrane (stained pink in HA2), which is composed of the lamina rara (lightly stained), the lamina densa (dark layer) and the lamina reticularis (fibrous). Together, the rara and densa are also called the basal lamina and are secreted by the epithelium. These layers bind the epithelial cells to the underlying connective tissue which begins in the lamina reticularis.