کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9436566 | 1615696 | 2005 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Development of the human fetal cochlear nerve: a morphometric study
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کلمات کلیدی
OHCVCNABRStereology - استریولوژیOntogeny - انتگرالstandard deviation - انحراف معیارIHC - ایمونوهیستوشیمیTem - این استembryonic day - روز جنینیpostnatal day - روز پس از زایمانouter hair cell - سلول بیرونی موInner hair cell - سلول داخلی داخلیAsymmetry - عدم تقارنAuditory nerve - عصب شنواییCochlear nerve - عصب کچلرMyelination - میلیناسیونTransmission electron microscopy - میکروسکوپ الکترونی عبوریventral cochlear nucleus - هسته حلقوی شکمیauditory brainstem response - پاسخ شنوایی مغز
موضوعات مرتبط
علوم زیستی و بیوفناوری
علم عصب شناسی
سیستم های حسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Ontogenesis of the human peripheral auditory pathway is relatively less explored. While the distal part of the auditory perception apparatus (i.e. the cochlea) received attention, studies on the neural element carrying information to the brainstem (i.e. the cochlear nerve) are scarce. In the present study, axonal differentiation, maturation and myelination of the distal end of the human cochlear nerve (CN) were assessed using light and electron microscopy. Seven human fetuses of 12, 15, 18, 20, 22, 28 and 38 weeks' gestation (WG) were analyzed. Light microscopy revealed nerve fascicles as early as 12 WG, initially arranged loosely but later compacted by 18 WG. Myelinated fibers were clearly detected at 28 WG. Ultrastructurally, at 12 WG developing Schwann cells were present between the thin unmyelinated axons. At 15 WG, the fascicular arrangement was distinct with blood vessels in the perineurium. The maximum number of axons was found at 20 WG, which subsequently reduced to reach the adult level at 22 WG. The myelinated axons in the CN were first observed on the left side at 20 WG, following which the number and proportion of myelinated axons increased until term, incorporating both small and large axons. The right CN lagged behind in maturation. Axon size also increased with age. Thus, the maturation of the human CN commences during the mid-gestation period and produces exuberant axons that are eventually pruned at a time when axons start to myelinate. During this developmental period the human CN maintains maturational asymmetry, the functional consequences of which remain to be elucidated.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Hearing Research - Volume 202, Issues 1â2, April 2005, Pages 74-86
Journal: Hearing Research - Volume 202, Issues 1â2, April 2005, Pages 74-86
نویسندگان
Bappaditya Ray, Tara Sankar Roy, Shashi Wadhwa, Kallol Kumar Roy,