title: Use of fluorescence in a modified disector method to estimate the number of myocytes in cardiac tissue.
abstract: BACKGROUND
  Conventional disector methods currently require considerable financial, technical and operational costs to estimate the number of cells, including cardyomyocytes, in a 3D area.
  
  
  OBJECTIVE
  To use fluorescence microscopy in a modified disector method to determine the number of myocytes in cardiac tissue in normal and pathological conditions.
  
  
  METHODS
  The study employed four-month-old male Wistar rats with weight of 366.25 ± 88.21g randomized in control (CG, n=8) and infected (IG, n=8) groups. IG animals were inoculated with T. cruzi Y strain (300,000 trypomastigotes/50g wt). After eight weeks, the animals were weighted and euthanized. The left ventricles (LV) were removed for stereological analysis of numerical density of cardiomyocytes (Nv[c]) and total number of these cells in the LV (N[c]). These parameters were estimated using a fluorescent disector (FD) and compared with the conventional optical (OD) and physical (PD) disector methods.
  
  
  RESULTS
  In both disector methods, IG animals presented significant decrease of Nv[c] and N[c] compared to CG animals (P< 0.05). There was no significant difference in these variables despite the disector method applied in CG and IG animals (P> 0.05). A strong correlation, equal or above 96%, was obtained between FD, OD and PD.
  
  
  CONCLUSIONS
  The FD method seems to be equally reliable to determine Nv[c] and N[c] in normal and pathological conditions and presents some advantages compared to conventional disector methods: reduction of histological slices and images in the stereological analysis, reduction of time to analyze the images, construction of FD in simple microscopes using the epifluorescence mode, distinction of disector planes in lower magnifications.
authors.affiliation: Universidade Federal de Viçosa, MG, Brazil. romuonovaes@yahoo.com.br
authors.forename: Rômulo Dias
authors.initials: RD
authors.lastname: Novaes
authors.forename: Arlete Rita
authors.initials: AR
authors.lastname: Penitente
authors.forename: André
authors.initials: A
authors.lastname: Talvani
authors.forename: Antônio José
authors.initials: AJ
authors.lastname: Natali
authors.forename: Clóvis Andrade
authors.initials: CA
authors.lastname: Neves
authors.forename: Izabel Regina Santos Costa
authors.initials: IR
authors.lastname: Maldonado
mesh_terms: D000818:Animals; D002452:Cell Count / Q000379:methods; D002598:Chagas Cardiomyopathy / Q000469:parasitology / Q000473:pathology*; D004195:Disease Models, Animal; D006352:Heart Ventricles / Q000469:parasitology / Q000473:pathology*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008856:Microscopy, Fluorescence / Q000191:economics / Q000379:methods*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000469:parasitology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014349:Trypanosoma cruzi