Age-Related Changes in Pre-Aortic Ganglion Cells of the Rat

Mulissa, Jickssa (2014) Age-Related Changes in Pre-Aortic Ganglion Cells of the Rat. Masters thesis, Addis Ababa University.

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Abstract

The age-related changes in morphology and numerical distribution of rat pre-aortic (celiac and superior mesenteric) ganglia were studied using histological techniques and stereological analysis. The pre-aortic ganglia from developing rats of embryonic days 16, 18, 20, postnatal days 1, 4, 7, 14, 21, adult rats of 4 months and ageing rats of 24 months were dissected out, immersion fixed, processed using standard histological technique and paraffin sectioned. The sections were stained with toluidine blue and analyzed with light microscope. The pre-aortic ganglia were seen as a ganglionic mass which were surrounded by a thick capsule. Each ganglionic mass was composed of three types of cells: neurons, glial cells or satellite cells and small granular cells. The size of pre-aortic neurons, which was estimated from the mean diameter of neurons, was observed to increase progressively with increasing age. This increment ranged from 4.0 μm at embryonic day 16 to 21.2 μm at ageing with mean of 5.5 - 16.5 and SEM 0.23 - 0.49. In addition, the change in the shape of pre-aortic neurons was estimated from the ratios of the long axis to the short axis. This coefficient of cell shape ranged from 1.0 μm at embryonic day 16 to 2.3 at ageing with mean of 1.3 - 1.7 and SEM of 0.04 - 0.07. Stereological estimation of the volume of the ganglia employing the cavalieri principle showed that the size of pre-aortic ganglia progressively increased with increasing age. The progressive increment in the volume was uniform at postnatal day 1 to 21, but the percentage increment between 21st day and 4th month and between 4th month and 24th month was 66% and 73%, respectively, for CG and 68% and 67%, respectively, for SMG. The numerical density (number of neurons per unit volume) estimated by a physical dissector analysis, progressively decreased with increasing age. The progressive decrement observed was uniform at postnatal day 1 upto 21, vi but the percentage decrement was 75% for CG, 78% for SMG between 21st day and 4th month and 66% for both CG and SMG between 4th month and 24th month. However, there was no significant difference among the total number of neurons found in the pre-aortic ganglia at the different age groups. In addition, the volume fraction of neurons which was estimated from the ratio of neurons within the ganglia, showed a progressive decrease with increasing age. This decrement was uniform at postnatal day 1 to 21, but the percentage decrement was 63% for both CG & SMG between 21st day and 4th month and 76% for CG, 85% for SMG between 4th month and 24th month. Furthermore, the total volume of pre-aortic neurons progressively increased from postnatal day 1 upto adult, but the mean volume increased from 0.059 to 0.066 mm3 for CG and from 0.058 to 0.064 mm3 for SMG from adult to ageing. It is concluded that the rat pre-aortic ganglia reveals changes in the morphology and numerical distribution of neurons during development, during adulthood and ageing. These age-related changes may be due to the increased amount of interstitial connective tissue and the accumulation of lipofuscin granules (age-pigments). In addition, the changes may indicate the functions of the pre-aortic ganglia target organs, which includes stomach, intestine and accessory glands (liver and pancreas).

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Pre-aortic ganglia; celiac ganglia; superior mesenteric ganglia; extracellular matrix; development; ageing; morphology; stereology
Subjects:	Q Science > Q Science (General)
Divisions:	Africana
Depositing User:	Vincent Mpoza
Date Deposited:	21 Jun 2018 07:13
Last Modified:	21 Jun 2018 07:13
URI:	http://thesisbank.jhia.ac.ke/id/eprint/5266

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