Comparison of morphometric aspects of light and electron microscopy of the hypoglossal nerve between young and aged male wistar rats

Age-related changes occur in many different systems of the body. Many elderly people show dysphagia and dysphonia. This research was conducted to evaluate quantitatively the morphometrical changes of the hypoglossal nerve resulting from the aging process in young and aged rats. Through an experimental study ten male wistar rats [4 months: 5 rats, 24 months: 5 rats] were selected randomly from a colony of wistars in the UWC. After a fixation process and preparation of samples of the cervical portion of the hypoglossal nerve of these rats, light and electron microscopic imaging were performed. These images were evaluated according to the numbers and size of myelinated nerve fibers, nucleoli of Schwann cells, myelin sheath thickness, axon diameter, and g ratio. All data were analyzed by Mann-Whitney, a non-parametric statistical test. In light microscope, numbers of myelinated nerve fibers, the mean entire nerve perimeters, the mean entire nerve areas and the mean entire nerve diameters in young and aged rats' were not significantly different between the two groups. In electron microscope, numbers of myelinated axons, numbers of Schwann cell nucleoli and the mean g ratios of myelinated axon to Schwann cell in young and aged rats were not significantly different. The myelinated fiber diameters, the myelin sheath thicknesses, myelinated axon diameters and the mean g ratio of axon diameter to myelinated fiber diameter in young and aged fibers were significantly different. The mean g ratio of myelinated nerve fibers of peripheral nerves stabilizes at the level of 0.6 after maturation and persists without major change during adulthood. This ratio of axon diameter to fiber diameter [0.6] is optimum for normal conduction velocity of neural impulses. Our study indicated that the g ratio of myelinated nerve fiber of the hypoglossal nerve decreased prominently in aged rats and can be a cause of impairment in nerve function in old age. Thus, prospective studies concerning electrophysiological and conductive properties of the peripheral nerve could be useful to clarify further the effects of aging on peripheral nerves

Rubinstein-Taybi Syndrome; a case report

Rubinstein-Taybi Syndrome is a rare genetic disorder with characteristic features including downward slanting palpebral fissures, broad thumbs and halluces, and mental retardation. Systemic features may involve cardiac, auditory, ophthalmic, endocrine, nervous, renal and respiratory systems. This syndromeis sporadic in nature and has been linked to microdeletion at 16p 13.3 encoding CREB-binding protein gene [CREBBP]. We report a 15-years-old girl, a known case of chronic renal failure, with downward slanting palpebral fissures towardthe ears, hypertelorism, short stature, beaked nose, micrognathia, strabismus, dental anomalies, large toes, broad thumbs, and mental retardation