Superior cervical ganglionectomy results in the loss of pineal concretions in the adult male gerbil (meriones unguiculatus)

Twelve weeks after bilateral superior cervical ganglionectomy, the number of pineal concretions in adult male gerbils was drastically decreased irrespective of photoperiodic treatment. These findings present further evidence that pineal concretions may be related to the metabolic activity of the gland. It is suggested that the pineal concretions of the gerbil are associated, in a yet unknown way, to the metabolism of the gland and that an active pineal is essential to maintain the large number of concretions seen in the normal state.