title: [Stereology of the myocardium in young and aged rats].
abstract: OBJECTIVE
  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 7 microns 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 1.7 g, 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 x 10(4) to 6.19 x 10(4)/mm3 and 15.64 x 10(4) to 10.72 x 10(4) myocytes, respectively. Simultaneously, the V(myocyte) increased from 5.42 x 10(3) to 13.26 x 10(3) mm3. These differences were statistically significant (p < 0.05).
  
  
  CONCLUSIONS
  Myocardial changes, comparing young rats with aged ones suggest loss of myocytes (increased apoptosis?) with simultaneous myocyte hypertrophy.
authors.affiliation: Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro-UERJ.
authors.forename: M B
authors.initials: MB
authors.lastname: Aguila
authors.forename: C A
authors.initials: CA
authors.lastname: Mandarim-de-Lacerda
authors.forename: M I
authors.initials: MI
authors.lastname: Apfel
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D002452:Cell Count; D006321:Heart / Q000033:anatomy & histology; D008297:Male; D009206:Myocardium / Q000166:cytology*; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar
vernacular_title: Estereologia do miocárdio de ratos jovens e idosos.