Birbeck granules

Birbeck granules are "tennis-racket" or rod shaped cytoplasmic organelles with a central linear density and a striated appearance. Function is under question, but one theory is that they migrate to the periphery of the Langerhans cells and release its contents into the extracellular matrix. Another theory is that the Birbeck granule functions in receptor-mediated endocytosis, similar to clathrin-coated pits.

Birbeck granules were discovered by Michael Stanley Clive Birbeck (1925-2005), a British scientist and electron microscopist who worked at the Chester Beatty Cancer Research Institute, London from 1950 until 1981.