ABSTRACT
PURPOSE : 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.
Subject(s)
Animals , Female , Male , Body Size/physiology , Body Weight/physiology , Rats, Wistar/growth & development , Tail/growth & development , Tibia/growth & development , Age Factors , Reference Standards , Sex Factors , Time Factors , Tail/anatomy & histology , Tibia/anatomy & histologyABSTRACT
Evaluations of weight and cephalic perimeter are very used to study the growth and development in human beings. Similar measures, called murinometrics, have been an efficient resource to study the effects of nutritional and pharmacologic manipulations on the somatic development in rat. The aim of this study is to describe a method of evaluation which offers a higher accuracy in the collect of data in the study of somatic development in Wistar rat. Measurements were realized in latero-lateral axis of skull; Antero-posterior axis of skull; Longitudinal axis; Length of tail in 60 wistar rat during breastfeeding period. The most suitable method of measurement respects predetermined anatomic points, the use of the suitable scapus of pachymeter as well as its accuracy.
Evaluaciones de peso y perímetro cefálico son muy utilizadas para el estudio del crecimiento y desarrollo en humanos. Medidas semejantes, denominadas murinométricas, han sido un recurso eficiente para el estudio de los efectos de manipulaciones nutricionales y farmacológicos sobre el desarrollo somático en ratas. El objetivo de este trabajo fue describir un método de evaluación que ofrece mayor exactitud en la recolección de los datos, en el estudio del desarrollo somático en ratas Wistar. Fueron realizadas medidas en el eje látero-lateral del cráneo (ELLC); eje ántero-posterior del cráneo (EAPC); eje longitudinal (EL) y largo de la cola (LC), en 60 ratas Wistar, durante el periodo de amamantación. Se observó, como método más adecuado de medición, el que se relaciona con puntos anatómicos predefinidos, uso del asta adecuada del instrumento de medida (paquímetro), así como la precisión de su exactitud.
Subject(s)
Animals , Rats , Skull/anatomy & histology , Tail/anatomy & histology , Skull/growth & development , Tail/growth & development , Body Weight , Rats, WistarABSTRACT
We investigated the somatic maturation of neonate rats treated during the suckling period with citalopram, a selective serotonin reuptake inhibitor. Groups with 6 male neonates were randomly assigned to different treatments 24 h after birth. Each litter was suckled by one of the dams until the 21st postnatal day. Body weight, head axis and tail length were measured daily from the 1st to the 21st postnatal day. Time of ear unfolding, auditory conduit opening, incisor eruption, and eye opening was determined. Pups received 5 mg (Cit5), 10 mg (Cit10) or 20 mg/kg (Cit20) citalopram sc, or saline (0.9 percent NaCl, w/v, sc). Compared to saline, body weight was lower (24.04 percent, P < 0.01) for Cit10 from the 10th to the 21st day and for Cit20 from the 6th to the 21st day (38.19 percent, P < 0.01). Tail length was reduced in the Cit20 group (15.48 percent, P < 0.001) from the 8th to the 21st day. A reduction in mediolateral head axis (10.53 percent, P < 0.05) was observed from the 11th to the 21st day in Cit10 and from the 6th to the 21st day in Cit20 (13.16 percent, P < 0.001). A reduction in anteroposterior head axis was also observed in the Cit20 group (5.28 percent, P < 0.05) from the 13th to the 21stday. Conversely, this axis showed accelerated growth from the 12th to the 21stday in the Cit5 group (13.05 percent, P < 0.05). Auditory conduit opening was delayed in the Cit5 and Cit20 groups and incisor eruption was delayed in all citalopram groups. These findings show that citalopram injected during suckling to rats induces body alterations and suggest that the activity of the serotoninergic system participates in growth mechanisms.
Subject(s)
Animals , Male , Female , Rats , Animals, Newborn , Animals, Suckling , Citalopram , Selective Serotonin Reuptake Inhibitors , Weight Gain , Rats, Wistar , Tail/growth & development , Time FactorsABSTRACT
A observaçäo de fibroblastos ao microscópio eletrônico da cauda de girinos totalmente desenvolvidos e no evolver de sua regressäo, permitiu constatar que os mesmos estavam bem desenvolvidos quando a cauda atingia o seu maior comprimento. No entanto, durante sua regressäo, notamos a presença de fibroblastos apresentando vesículas intracitoplasmáticas com fibrilas colágenas em vários estágios de reabsorçäo, fortalecendo assim a hipótese de que essas células atuam tanto na síntese quanto na degradaçäo das fibrilas colágenas durante a metamorfose