Brain tissue transplanted to the anterior chamber of the eye: 2. Fluorescence histochemistry of immature catecholamine and 5-hydroxytryptamine neurons innervating the rat vas deferens

Summary Small pieces of the wall of the rat vas deferens were homologously transplanted to the anterior chamber of the eye together with small pieces of embryonic brain stem containing either developing noradrenaline (NA) cells of the locus coeruleus or 5-hydroxytryptamine (5-HT) neurons of the developing raphe system. The eyes of the recipients were sympathetically denervated. The double transplants became rapidly vascularized from the host iris. After 31/2 months the irides, together with their two transplants were analyzed by Falck-Hillarp fluorescence microscopy. Both the NA and the 5-HT neurons had survived and matured in the eye. Fluorescent varicose nerve terminals of the NA and 5-HT type respectively were found in all three potential receptor areas, i.e. within the CNS transplants, in the host irides and in the vas deferens transplants. In the latter, the newly formed monoamine nerve terminals arborized mainly within a well developed smooth muscle layer. The density of such new fibres was higher than or similar to that of the normally present sympathetic plexus in areas of the transplant close to the CNS transplant and lower in areas at a distance from the CNS transplant. It is concluded that immature central NA and 5-HT fibres are able to grow simultaneously into different types of sympathetically denervated smooth muscle tissues to form networks of fibres in the receptor organs resembling the normal sympathetic innervation.Supported by the Swedish Medical Research Council (04X-3185), and by grants from Magnus Bergvalls Stiftelse, Tidningen Expressens Prenatalforskningsfond and Karolinska Institutets fonder. We thank miss Ingrid Strömberg for skilful technical assistance. Nialamide^® was generously donated by Swedish Pfizer AB.