title: Development of dynorphin-like immunoreactive auditory nerve terminals in the chick.
abstract: The novel discovery that auditory nerve terminals in the chick cochlear nucleus magnocellularis (NM) are immunoreactive for the opioid peptide dynorphin (DYN) was recently reported [3]. The present study examines the development of DYN-immunoreactivity (DYN-I) in auditory nerve terminals in NM from embryos through young post-hatch chicks. No DYN-I was observed in NM at embryonic day 13 (E13). DYN-I first appeared at E16 as short flat structures partially surrounding NM cell bodies. Around post-hatch day 1 (P1), these structures had a more rounded, chalice-type of morphology reminiscent of the specialized auditory nerve terminals found in birds, the end-bulbs of Held. At P6, most NM neurons were circumscribed by a prominent DYN-I calyceal-type of ending. By P13, fewer NM cells were ringed by this DYN-I and by the third post-hatch week, there was very little DYN-I in NM. There were no obvious differences in the density of DYN-I terminals across either the rostrocaudal length or the mediolateral width of NM at any age examined. These results suggest that during a restricted time of development, end-bulbs of Held in the chick NM contain DYN.
authors.affiliation: Dept. of Biology, Texas Woman's University, Denton 76204-5799, USA. f-code@venus.twu.edu
authors.forename: R A
authors.initials: RA
authors.lastname: Code
authors.forename: A E
authors.initials: AE
authors.lastname: McDaniel
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D017626:Cochlear Nucleus / Q000737:chemistry* / Q000196:embryology / Q000254:growth & development; D004399:Dynorphins / Q000032:analysis*; D007150:Immunohistochemistry; D009411:Nerve Endings / Q000737:chemistry* / Q000196:embryology / Q000254:growth & development; D000159:Vestibulocochlear Nerve / Q000737:chemistry* / Q000196:embryology / Q000254:growth & development
chemical_list: D004399:Dynorphins