Stage dependent development of intraocular cochlear grafts.
The intraocular grafting technique was employed to test whether the peripheral hearing organ, the cochlea, is capable of survival and an organized development in total isolation from the temporal bone. Rat cochleae obtained from gestation day 16, postnatal day 1 and 7 were chosen for transplantation into the anterior chamber of the eye of adult Sprague-Dawley rats. The grafts were maintained in the anterior chamber for 6, 10, or 15 weeks survival time. The salient features of this study is that 1) cochlear structures survive and, 2) the cochlear structures develop beyond their pre-grafted stage as determined from light and electron micrographs. In the present study, the grafts obtained at gestation day 16 (GD 16) and postnatal day 1 gave a much higher rate of survival and development than the postnatal day 7 grafts. In addition, grafts maintained for either 6 or 10 weeks had a better survival rate than those grafts left for 15 weeks. It is estimated from light and electron micrographs that the gestation day 16 otocysts that were maintained for 10 weeks, developed to the equivalent of a postnatal day 10 cochlea. The grafts obtained from postnatal day one rats developed to the equivalent of approximately 14 days after birth. Interestingly, in the absence of synaptic contact, the inner and outer hair cells were capable of survival, differentiation and maturation. It remains to be determined if the spiral ganglion cells require additional neurotrophic factors for survival in the anterior chamber of the eye.
Canlon
B
B
Department of Physiology II, Karolinska Institutet, Stockholm, Sweden.
Li
H
H
Olson
L
L
Hultcrantz
M
M
Borg
E
E
D000818:Animals; D000867:Anterior Chamber; D002454:Cell Differentiation; D002470:Cell Survival; D003051:Cochlea / Q000166:cytology / Q000196:embryology / Q000254:growth & development / Q000637:transplantation*; D003053:Cochlear Duct / Q000254:growth & development / Q000648:ultrastructure; D006085:Graft Survival; D006198:Hair Cells, Auditory / Q000166:cytology / Q000254:growth & development; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley; D013136:Spiral Ganglion / Q000166:cytology / Q000254:growth & development; D016042:Transplantation, Heterotopic