title: Allometric relationships among body mass, MUZZLE-tail length, and tibia length during the growth of Wistar rats.
abstract: OBJECTIVE
  To investigate allometric relationships among body mass (BM), muzzle-tail length (MTL), and tibia length (TL) in Wistar rats and establish their growth rate change parameters.
  
  
  METHODS
  Eighteen male and 18 female Wistar rats were studied from the 3rd to the 21st week of age. BM, MTL, and TL were measured daily, and relative growth was compared using allometry.
  
  
  RESULTS
  A positive correlation between BM and MTL (p<0.05) and BM and TL (p<0.05) was observed. Males and females showed comparable curves; however, females had turning points at a younger age. The allometric relationship between BM and MTL presented a regular increase until reaching a mass of 351 g (males) and 405 g (females). BM and TL showed an initial increase until 185 g (males) and 182 g (females), and then reached a plateau that finished at 412 g (males) and 334 g (females), to display another increase.
  
  
  CONCLUSIONS
  The allometric relationship of body mass with animal length and tibia length was comparable for male and female rats, with female rats maturing earlier. Animal longitudinal growth occurred in a single stage. In contrast, tibia length depicted two stages of accelerated growth with an intermediate period of deceleration.
authors.affiliation: Faculty of Medicine of Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, SP, Brazil.
authors.forename: Hildemberg Agostinho Rocha de
authors.initials: HA
authors.lastname: Santiago
authors.affiliation: Faculty of Medicine of Ribeirao Preto, USP, Ribeirao Preto, SP, Brazil.
authors.forename: Lucas Rodolfo
authors.initials: LR
authors.lastname: De Pierro
authors.affiliation: Faculty of Medicine of Ribeirao Preto, USP, Ribeirao Preto, SP, Brazil.
authors.forename: Rafael Menezes
authors.initials: RM
authors.lastname: Reis
authors.affiliation: Faculty of Medicine of Ribeirao Preto, USP, Ribeirao Preto, SP, Brazil.
authors.forename: Antônio Gabriel Ricardo Engracia
authors.initials: AG
authors.lastname: Caluz
authors.affiliation: Faculty of Medicine of Ribeirao Preto, USP, Ribeirao Preto, SP, Brazil.
authors.forename: Victor Barbosa
authors.initials: VB
authors.lastname: Ribeiro
authors.affiliation: Faculty of Medicine of Ribeirao Preto, USP, Ribeirao Preto, SP, Brazil.
authors.forename: José Batista
authors.initials: JB
authors.lastname: Volpon
mesh_terms: D000367:Age Factors; D000818:Animals; D049628:Body Size / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D005260:Female; D008297:Male; D017208:Rats, Wistar / Q000254:growth & development*; D012015:Reference Standards; D012737:Sex Factors; D013623:Tail / Q000033:anatomy & histology / Q000254:growth & development*; D013977:Tibia / Q000033:anatomy & histology / Q000254:growth & development*; D013997:Time Factors