Ultrastructural study of an unusual crystalloid in the Sertoli cells of the bull.

An unusual type of crystalloid was found in the cytoplasm of bull Sertoli cells. Located in the immediate vicinity of the nucleus, this crystalloid is a non-membrane bound ovoid-shaped structure with maximum dimensions of 10 microns in length and 3 microns in width. It consists of closely packed parallel arrays of zigzag coursing 13 nm filaments and is closely associated with a number of cell organelles like mitochondria, smooth endoplasmic reticulum, lysosomes and the juxtanuclear network of vimentin filaments. This specific aspect is discussed in relation to a possible role in the transport of steroidogenic metabolites and/or other secretory products.