Paracrystalline arrays in atypical cristae and mitochondrial division.

Paracrystalline arrays in atypical cristae were observed in a few large mitochondria in the process of replication, in the follicular cell of the normal and gonadectomized rabbit thyroid gland. They were about 30 nm in diameter and spaced approximately 35-40 nm apart, and oblique sections showed parallel arrays which had a pitch of 25 nm. The number of inclusions varied in number and were similar to those reported in the normal follicular cell. The site of replication was often at the base of the mitochondrion and in some instances the continuity of the outer membrane was present. The helical nature of the inclusions suggests that they may be associated with the complex proteins of the inner mitochondrial membrane and space which have the capacity of helix formation. The cristae with the paracrystalline arrays appear to be in the orthodox configuration, a non-energized stage of the energy cycle. The mitochondria probably utilizes its unique ability to control respiration according to its functional requirement during replication.