Puberty is a dynamic period of physical growth, sexual maturation, and psychosocial achievement that generally begins between age 8 and 14 years. The age of onset varies as a function of sex, ethnicity, health status, genetics, nutrition, and activity level. Puberty is initiated by hormonal changes triggered by the hypothalamus. Children with variants of normal pubertal development--both early ...

Abdominal and cerebral angiostrongyliasis are two important infections produced by metastrongylid worms, the former occurring in Central and South America and the later in Asia and Pacific Islands. Drug treatment is a challenge since the worms and its evolving larvae live or migrate inside vessels and efficient killing of the parasites may produce more severe lesions. Larvicidal effect of certa...

Growth hormone (GH) affects somatic growth, sexual maturation, body composition and metabolism, as well as aging and longevity. Mice lacking GH or GH receptor outlive their normal siblings and exhibit symptoms of delayed aging associated with improved insulin signaling and increased stress resistance. Beneficial effects of eliminating the actions of GH are counterintuitive but conform to the co...

The addition of two 3-h periods of very dim light, one before and one after a normal 8-h photoperiod, advances sexual maturity in pullets by about a week. This trial tested the hypothesis that dim light given before a short day of normal intensity is linked to form a more stimulatory day length and that dim light given after it is photosexually ignored. Pullets were reared from 2 d of age on 8-...

Understanding life-history evolution requires knowledge about genetic interactions, physiological mechanisms and the nature of selection. For platyfish, Xiphophorus maculatus, extensive information is available about genetic and physiological mechanisms influencing life-history traits. In particular, alleles at the pituitary locus have large and antagonistic effects on age and size at sexual ma...

Sex and reproduction sculpt brain and behavior throughout life and evolution. In vertebrates, gonadotropin-releasing hormone (GnRH) is essential to these processes. Recent advances have uncovered novel regulatory mechanisms in GnRH signaling, such as the initiation of sexual maturation by kisspeptins. Yet despite our increasing molecular knowledge, we know very little about environmental influe...

In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may vary more among than within broods, parents may use this information to adjust their parental allocation to the current brood accordingly. We tested this hypot...

Statural growth is dependent on hereditary and environmental factors, i.e disease, nutrition. The improvement of socioeconomic conditions that took place during the 20th century resulted in a secular trend towards greater height and earlier sexual maturation. Greek society has changed dramatically from a mainly agricultural society at the beginning of the 20th century to a mainly urban one in t...

Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing ...

Method Twenty female Sprague Dawley rat (SD rat) were randomly divided into two groups according to their bedding types. The 1 group was raised in wood shaving bedding as a control and 2 one was in corncob bedding as an endocrine disrupting agent. Each group was checked daily for the first day of vaginal opening, and their vaginal smears were collected to determine estrous cyclicity after vagin...