introduction: genetic and health factors along with ethnicity and geographic location are factors that affect the time of puberty onset. the aim of the present study was to evaluate the mean age of onset of puberty and its stages in boys of yazd. methods: this cross- sectional study with random clustering sampling method was conducted on 1018 healthy 9-16 years old male students of yazd. all ca...

size at sexual maturity and patterns of somatic growth are important aspects of reproductive history of crab. the main purpose of this study is to provide an estimate for the onset of morphological sexual maturity in mangrove crab, opusia indica from a population located in korangi creek intertidal mud flat (karachi, pakistan) based on relative growth. the crabs were monthly collected through q...

Onset of sexual maturation is a trait of extreme importance both evolutionarily and economically. Unsurprisingly therefore, domestication has acted to reduce the time to sexual maturation in a variety of animals, including the chicken. In comparison with wild progenitor chickens [the Red Junglefowl (RJF)], domestic layer hens attain maturity approximately 20% earlier. In addition, domestic laye...

OBJECTIVE To provide clinically meaningful, normative reference data that describe the timing of sexual maturity indicators among a national sample of US children and to determine the degree of racial/ethnic differences in these estimates for each maturity indicator. METHODS Tanner staging assessment of sexual maturity indicators was recorded from 4263 non-Hispanic white, black, and Mexican A...

the present study was conducted to estimate correlations among performance and egg quality traits in iranian native fowl. data were collected from 21,679 birdsat the isfahan native fowl breeding center to derive genetic parameters for performance traits and egg quality traits were measured on eggs of 1,020 birds. genetic correlations of performance and egg quality traits were estimated with a b...

the current study investigated the effect of short-term selection for four week body weight (bw) on performance of divergent lines of japanese quail and their crosses. the mean of bw at hatching time, one, two, three and four week oldand bw at sexual maturity time, age at sexual maturity, number of eggs (from 50 to 100 days old), mean of egg weight, percentage of fertility and hatchability in e...

This study was conducted to determine the concentration of five heavy metals, including lead, cadmium, mercury, arsenic, and chromium in muscle, liver and gills of the gray mullet, Liza aurata in southern part of the Caspian Sea. The samples were collected during sexual maturity (in the fall) and sexual rest (in the spring). The mean concentration of lead, cadmium, mercury, arsenic, and chromiu...

Twenty four farmed great sturgeon, Huso huso (including 8 males and 16 females) over 6 years old were used to develop a method for determination of sex and maturity stages. Seasonal gonadal tissue and blood samples were collected from farmed great sturgeon for three years. The sex and stages of maturity were determined by histology and laparoscopy at the beginning and end of experiment. Plasma ...

Age at maturity has been suggested to be an important life-history trait with substantial potential for influencing the evolution of life histories. Using known reproductive histories of 90 female wood ducks (Aix sponsa) from a long-term study (1982–96), we investigated the fitness consequences of changes in age at maturity. Female wood ducks that attained sexual maturity as yearlings had a sig...