Fine structural observations on untreated and ACTH treated adrenocortical cells of the zona reticularis of Syrian hamsters

Summary The fine structure of the zona reticularis of adult Syrian hamsters was studied and compared with that of hamsters given subcutaneous injections of ACTH (10 units daily) for three days. The general ultrastructural features of the cells of the reticularis were described. The major emphasis however, was placed upon the mitochondria which underwent alterations following ACTH injections. Untreated hamsters exhibited elongated mitochondria, attenuated in their middle parts, which formed wrappings around structures, frequently other mitochondria. The tubular cristae of the majority of the mitochondria projected only part of the way into the matrix so that the interior were relatively free of tubules. In many cases the tubules were arranged parallel with the surface so that the mitochondria appeared to be surrounded by numerous membranes. The animals treated with ACTH very rarely showed elongated, attenuated mitochondria: The mitochondria were more nearly equal in size compared with those of untreated animals and the tubular cristae occupied the majority of the interior of the mitochondria. The possible relationship between the mitochondrial changes and increased steroid synthesis was discussed.Research supported by USPHS Grant AM 08222-02, NB 05665-01 and Anatomy Training Grant 5 T 1 GM 459-05.Appreciation is extended to Doctor Donald Duncan whose research is supported by USPHS Grant NB 00690-10 S 1 for the use of the electron microscope and to Mr. Joe Mascorro for technical assistance.