AbstractTransplantations were made of fetal pineal glands (crown‐rump length, CRL, 19–30 mm) or pineal glands from adult male rats to the anterior chamber of the eye of the rat. Studies were performed with regard to the importance of the age of the donor animal (and thereby the degree of maturation and innervation of the gland to be transplanted) for the possible development of denervation supersensitivity. The transplants were cultured in a medium containing14C‐serotonin. Increased production of14C‐N‐acetylserotonin (NAcS) was used as the main criterion for β‐adrenergic stimulation. 4 experimental groups were obtained by transplanting fetal or adult pineals to intact or sympathetically denervated eyes. In all 4 groups β1‐stimulation (KWD 2033 10‐6M) increased14C‐NAcS formation. The response to β‐stimulation was significantly higher in denervated fetal pineal transplants than in innervated fetal transplants and thus demonstrating β‐receptor supersensitivity. It was concluded that a) the ability to respond to β‐adrenoceptor stimulation with increased14C‐NAcS formation develops between the 18th and 20th day of gestation, b) transplants derived from fetal as well as from adult rats can respond to β‐adrenergic stimulation, c) this sensitivity also developsin oculoin transplants that at the time of transplantation lacked the capacity to increase their14C‐NAcS formation in response to treatment with β‐agonist, d) denervation supersensitivity occurs in fetal transplants that became mat