Explorations of otic transplantation.
Embryonic rat inner ears were transplanted to the anterior chamber of the eyes of adult rats. While considerable development was evident, the structures present were limited to the vestibular division. We hypothesized that this selective survival could be due to the rate of vascularization. To test the effects of graft vascularization we made transplants in which the internal structures were exposed by removing the apex and base of the developing cochlea. The transplants were rapidly vascularized by the iris. Many of the soft labyrinthine structures of the cochlea from 1-day-old donors showed considerable development, including the spiral limbus, basilar membrane, and organ of Corti. To test the possibility that the cochlea requires inductive or trophic support beyond Embryonic Day 15 (E15), we cotransplanted the embryonic inner ear with developing brain stem. In these transplants, we observed improved development of the cochlea, with spiral ganglion cells and an organ of Corti possessing hair cells, Deiter's cells, and pillar cells. To further address the effect of developing CNS tissue on the development of grafted inner ear, we transplanted E15 inner ears to either the cortex or the brain stem of neonatal rats. In these experiments we have seen evidence of both vestibular and cochlear sensory surfaces. In the cochlea, an organ of Corti-like structure can be seen. The possibility of neural connections with the host brain has yet to be investigated.
Hughes
S E
SE
Sensory Neuroscience Laboratory, Central Institute for the Deaf, St. Louis, Missouri 63110.
Silverman
M S
MS
D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000502:physiology / Q000637:transplantation; D016380:Brain Tissue Transplantation / Q000502:physiology; D003051:Cochlea / Q000166:cytology / Q000502:physiology; D007758:Ear, Inner / Q000166:cytology / Q000502:physiology* / Q000637:transplantation*; D016332:Fetal Tissue Transplantation; D009925:Organ of Corti / Q000166:cytology / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D016042:Transplantation, Heterotopic