On the relationship between annulate lamellae and mitochondria in human parathyroid adenomas

Many chief cells and a few oxyphil cells of human parathyroid adenomas possessed cytoplasmic annulate lamellae of varying size and shape, often with separating electron lucent spaces. The membrane pairs constituting the lamellae exhibited electron lucent dilatations with membranous infoldings and septa. A close association was found between annulate lamellae and mitochondria that often occurred in dilated portions of the lamellae. A less conspicuous association was seen between annulate lamellae and rough endoplasmic reticulum, vesicles, lipoid bodies, and glycogen particles. Occasionally annulate lamellae were in close contact with the nuclei, which may indicate that they are derived from the nuclear membranes. Annulate lamellae may have different functions; when occurring in the chief cells and oxyphil cells of parathyroid adenomas, they might be involved in the formation of mitochondria, possibly facilitating a rapid conversion of chief cells into oxyphil cells.