stereology – ABC CARDIOL

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Artigo Original

Stereology of the myocytes in young and aged rats

Márcia Barbosa Águila et al. Carlos Alberto Mandarim-de-Lacerda Mara Ibis Rodrigues Apfel

PURPOSE: To determine the myocardial quantitative changes comparing young and aged animals by using the stereology. METHODS: Thirty rat hearts were studied (15 rats aged 3 months and 15 other rats aging 15 months). The hearts were removed, weighed, fixed in 10% buffered formaldehyde solution, embedded in paraffin, cut in 7µm thick slices and stained with HE and picro-sirius stains. In each group we counted 15 random microscopic fields. The following parameters were studied: Vv(myocyte) and Vv(interstitium)(%) (the volume densities of the cardiac myocyte and interstitium, determined by the point-counting method), and Nv(myocyte) (1/mm³) (the numerical density of the cardiac myocytes, determined with the disector method). The total number of myocytes (N[myocyte]) and the mean volume of the myocytes (V[myocytes]) were also determined. The differences were tested by the Mann-Whitney test.RESULTS: Cardiac weight increased from 1.1 to 1.7g, the Vv(myocyte) decreased from 76.7 to 72.2%, the Vv(interstitium) increased from 23.3 to 27.8%. The Nv(myocyte) and the N(myocyte) decreased from 14.76×10(4) to 6.19×10(4)/mm³ and 15.64×10(4) to 10.72×10(4) myocytes, respectively. Simultaneously, the V(myocyte) increased from 5.42×10³ to 13.26×10³mm³. These differences were statistically significant (p<0.05). CONCLUSION: Myocardial changes, comparing young rats with aged ones suggest loss of myocytes (increased apoptosis?) with simultaneous myocyte hypertrophy.

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Artigo Original

Morphology and stereology of the myocardium in hypertensive rats. Correlation with the time of nitric oxide synthesis inhibition

Leila Maria Meirelles Pereira et al. Glória Maria Moraes Vianna Carlos Alberto Mandarim-de-Lacerda

PURPOSE: To study structural changes of the myocardium in relation to the time of nitric oxide synthesis inhibition. METHODS: Four groups of 10 rats each were studied: 2 control groups and 2 groups with administration of L-Name (50mg/kg/day), one during 25 days and the other during 40 days. The animals were then sacrificed and the hearts were prepared for study in light microscopy, where sections stained by picro-sirius were studied with and without polarized light for analysis of the cardiac interstitium collagen. Volume densities of myocytes (Vv[m]) and interstitium (Vv[int]), the numerical density of myocytes (Nv[m]) and the mean cross-sectional area of myocytes were (A[m]) also determined. RESULTS: The L-Name animals were compared with the respective controls. In the L-Name rats, the tail arterial pressure increased 74.5 and 90.2% in the 25 days group and in the 40 days group, respectively. The heart weight increased 50% in the 25 days group and 28.6% in the 40 days group. The myocardium of the L-Name animals presented myocyte hypertrophy with increased A(m), perivascular and interstitial fibrosis, thickness of the tunica intima and tunica media of the intramyocardial arteries. In the 40 days group the L-Name animals had decreased Vv(m) and Nv(m) and increased Vv(int). CONCLUSION: Inhibition of nitric oxide synthesis provokes myocardial changes that progress with the time of L-Name administration. The stereology is useful to determine and to evaluate the myocardial changes in this model of arterial hypertension.

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Original Article

Comparison between right and left ventricular myocardia during the human fetal period. Stereological evaluation

Ricardo Xavier-Vidal et al. Kalil Madi

PURPOSE: To develop a stereological comparison between right (RV) and left ventricle (LV) myocardium during the third human gestational trimester. METHODS: Five human fetal hearts of the third trimester provided representative samples of 5 RV myocardium and 4 LV myocardium. The material was fixed in 10% buffered formaldehyde, and processed through routine methods. Fifteen microscopic fields were randomly chosen and counted in each ventricular myocardium using an “M-42” test system. The following stereological parameters were assessed: Vv (%), Lv (µm²), Sv (µm²/µm³), Vp (µm³), Nv (1/mm³) and total N. RESULTS: No significant difference between the stereological parameters of the myocardial structures assessed was evidenced, when comparing RV and LV. CONCLUSION: Right and left human ventricular myocardium are very similar during the fetal period at least in regard to their structural aspects.

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Stereology of the myocytes in young and aged rats

Morphology and stereology of the myocardium in hypertensive rats. Correlation with the time of nitric oxide synthesis inhibition

Comparison between right and left ventricular myocardia during the human fetal period. Stereological evaluation

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