[Acetylcholinesterase-positive innervation of the thymus in old rats after ovariectomy].

Surgical ovariectomy in aged rats entails regeneration of the involuted thymus. These results correlate with our study of acetylcholinesterase positive innervation of regenerated thymuses. We found out a marked autonomous innervation of the perivascular tissues, as well as that of the functional parenchyma of the thymus. We proved a significant increase in the density of ACHE-positive nerves in the thymus of aged rats after surgical ovariectomy. These results are considered to represent and indirect evidence of the fact that cholinergic nerves stimulate lymphopoiesis in the thymus. (Fig. 5, Ref. 9.)