A sac-like projection of glycogen-filled cells from the upper portion of the hair follicle. In most areas of the body, the glandular primordium regresses and disappears. In the axillary, areolar, and anogenital areas, the auditory canals, and eyelids, however, the glandular primordium begins to penetrate downward through the dermis. In some cases, the gland forms in the dermis and in others, in the subcutaneous fat.