Endocrine Abstracts

Puberty is the final stage of maturation of the hypothalamo-pituitary-gonadal axis and is characterized by changes in circulating gonadotropins and increased levels of sex steroids. There are both genetic and external factors (e.g. nutrition, stress) which can alter the onset of puberty. The aim of this study was to determine the onset of puberty in genetically homogeneous inbred mouse strains. Five strains were used: 129X1/SvJ, DBA/2J, C57BL/6J, CBA/CaJ and A/J. Various pubertal markers were determined: vaginal opening (VO), first vaginal cornification, onset of cyclicity in females, and balanopreputial separation (BPS) in males. There were significant differences between strains in the onset of puberty. The earliest VO was detected in A/J (day 20,8), then CBA/CaJ (day 24,45), DBA/2J (day 25,78), C57BL/6J (day 26,45) and the latest was in 129X1/SvJ (day 29,38). The earliest day for the first vaginal cornification was in CBA/CaJ (day 30,4), followed by C57BL/6J (day 33,18), A/J (day 34,3), 129X1/SvJ (day 36,28) and the latest was in DBA/2J (day 38,33). The earliest onset of cyclicity was detected in CBA/CaJ (day 40,3), then A/J (day40,4), 129X1/SvJ (day 47,19), C57BL/6J (day 48,67) and the latest was in DBA/2J (day 51,11). There was no correlation between the weight and the age at either VO, cornification or the onset of cyclicity among strains. The occurrence of BPS was later in males then the first sign of puberty (i.e. VO) in females. The earliest BPS was in CBA/CaJ (day 27,75), followed by 129X1/SvJ (day 29,37), C57BL/6J (day 29,71), A/J (day 30,8) and the latest was in DBA/2J (day 34). There was no correlation between the weight and the age at BPS among strains. Data indicate significant differences in pubertal parameters of inbred mouse strains.

This work was supported by grant from the EU Commission (PIONEER FOOD-CT-2005-513991).