Lamellar and tubular associations of the mitochondrial cristae: unique forms of the cristae present in steroid-producing cells.

This report provides a survey of mitochondrial structure in numerous cell types from all basic tissue types (epithelial, connective, muscular and nervous) with the main purpose being to determine the presence or absence of a form of the cristae previously termed the lamellar association (LA) (Anat. Rec. , 254 (1999) 534). The LA is a complex of closely apposed lamellar cristae within the inner membrane system of the mitochondria of Leydig cells, the steroid-producing cells of the testis. These lamellae are separated by a gap of approximately 4 nm. This survey has found no evidence of the LA in non-steroid-producing cells. The LA is a common cristae morphology in human Leydig cells, but is rare in marmoset Leydig cells, where instead, tubular associations (TA) are found. Cells of other steroid-producing cells are not included in this survey. Published micrographs from the literature do, however, have evidence of the existence of the LA and TA in other steroid-producing cells. It is concluded that these membrane substructures of the inner mitochondrial membrane are unique to steroid-producing cells. It is suggested that the LA is a region of the cristae, which is not involved with adenosine triphosphate (ATP) production, since the dimensions do not allow for F1 complexes on the matrix side of the cristae. The significance of this remains elusive.