A Morphometric Examination of the Ultrastructure of Regenerating Hypoglossal Motoneurons from the Rat and Analysis of Thyroid Hormone Influence on Motoneuron Structure and Regeneration
UNIFORMED SERVICES UNIV OF THE HEALTH SCIENCES BETHESDA MD
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The ultrastructure of regenerating hypoglossal motoneurons and their response to altered thyroid hormone status were examined. Morphometric techniques were utilized to evaluate uninjured and axotomized hypoglossal motoneurons from the rat. Hypoglossal nucleus volume and neuronal size were estimated from 50 micron sections. The volume and surface area of cell body organelles were determined from one micron and ultrathin sections. Seven to 30 days following axotomy the volume of the hypoglossal nucleus was significantly diminished p0.05. Significant neuronal enlargement p0.05 was detected 13 and 21 days following axotomy. Subcellular alterations were most prominent 7 days following nerve transection nucleolar volume was augmented, rough endoplasmic reticulum surface area was reduced, and non-Golgi smooth membrane surface area increased p0.05. Other organelles resisted the influence of axotomy. Ultrastructural parameters returned to control levels by 30 days following the nerve transection.
- Anatomy and Physiology
- Medicine and Medical Research