Relation between myelin area and axon diameter in the aortic depressor nerve of spontaneously hypertensive rats.
The hypothesis that the aortic depressor nerve (ADN) from spontaneously hypertensive rats (SHR) does not show the expected correlation between myelin sheath area and the axonal diameter of myelinated fibers detected in normotensive rat myelinated fibers was tested by means of regression analysis. Proximal and distal segments of ADN from 13 normotensive Wistar-Kyoto rats (WKY) and nine SHR were prepared for light microscopy study. With an image analysis system, the area of the myelin sheath and the axonal diameter of all myelinated fibers in each nerve were automatically measured. Regression lines were calculated for all nerve segments from each group. Differences between the regression lines were tested for slope and intercept and differences between the correlation coefficients were also tested. Regression lines for WKY data showed no differences between the proximal and distal segments either for slope or intercept. Proximal and distal SHR regression lines were not coincident between segments or when compared to WKY data. These results agree with previous observations that there are morphological differences between WKY and SHR myelinated fibers of the ADN suggesting that the SHR depressor nerve fibers present characteristics of axonal atrophy and/or remyelination.
Department of Surgery and Anatomy, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil.
Valéria Paula Sassoli
VP
Fazan
Helio Cesar
HC
Salgado
Geraldo Cássio
GC
dos Reis
Amilton Antunes
AA
Barreira
D000818:Animals; D001011:Aorta / Q000294:innervation / Q000502:physiology; D001284:Atrophy / Q000473:pathology; D001369:Axons / Q000473:pathology* / Q000648:ultrastructure; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D048429:Cell Size; D004195:Disease Models, Animal; D005260:Female; D006973:Hypertension / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D046529:Microscopy, Electron, Transmission; D009186:Myelin Sheath / Q000473:pathology* / Q000648:ultrastructure; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D009416:Nerve Regeneration / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014630:Vagus Nerve / Q000473:pathology* / Q000503:physiopathology / Q000648:ultrastructure; D020421:Vagus Nerve Diseases / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology