Fetal hypothalamic transplants in diabetic rats analysed by scanning electron microscopy.

Adult male Brattleboro rats with chronic diabetes insipidus underwent stereotaxic surgery wherein minced fragments of anterior hypothalamus from fetal rats, 17 days post-coitus, were stereotaxically positioned into the lumen of the host third cerebral ventricle. Host rats with fetal donor tissue were killed at various times following surgery and were prepared for correlative scanning-transmission electron microscopy. Examination with this technique revealed the presence of large neurografts which grew to occupy the entire lumen of the host third ventricle. Grafts were well vascularized and in addition exhibited remarkable numbers of supraependymal, cerebrospinal fluid-contacting neurons. The physical emergence of this cell line in proximity to viable grafts is discussed with respect to the biochemical influences that a neuropeptide producing fetal transplant has upon a peptide-deficient host.