Background: Up until now, the effect of thyroid hormones on the male reproductive organ, after puberty, is not well understood. OBJECTIVES: In the present study, the morpho-histometrical effects of thyroid hormone deficiency on the adult-male rat reproductive organs were investigated. MATHODS: Thirty adult male rats were randomly divided into three groups (n=10): control, hypothyroid, and hypot...

Gonadal steroid hormones act throughout the body to elicit changes in gene expression that result in profound effects on reproductive physiology and behavior. Steroid hormones exert many of these effects by binding to their respective intracellular receptors, which are members of a nuclear receptor superfamily of transcriptional activators. A variety of in vitro studies indicate that nuclear re...

BACKGROUND Rodent and in vitro studies have demonstrated the estrogenicity of bisphenol A (BPA). However, few studies have examined the relationship between human exposure to BPA and male reproductive function. OBJECTIVES We investigated the relationships between environmental BPA exposure and reproductive parameters, including semen quality and male reproductive hormones, in prospectively re...

This chapter reviews research on amphibians, focusing on questions about the hormonal mechanisms that regulate reproductive behaviors. In the roughskin newt (Taricha granulosa) and other amphibians, reproductive behaviors are activated and maintained by the usual set of sex steroid hormones—testosterone, 5αdihydrotestosterone, and 17β-estradiol. Sex steroids appear to act on the brain and activ...

During embryonic development, gonadal steroid hormones (androgens and estrogens) are thought to organize the sexual differentiation of the brain in the heterogametic sexes of higher vertebrates (males in mammals, females in birds). Brain differentiation of the homogametic sexes is thought to proceed by default, not requiring sex hormones for sex-specific organization. In gallinaceous birds such...

This review briefly highlights previous studies on the gonadotropin-releasing hormone (GnRH) and its approaches to improving fish reproduction in aquaculture industry. Reproductive system dysfunction of captive is main problem that has be treated depending compatibility species. caused by non-synchronized maturation female male broodstock, low quality broodstock. As shown studies, induced breed...

Only 2-5% of seminal fluid is composed of spermatozoa, while the rest is seminal plasma. The seminal plasma is a rich cocktail of organic and inorganic compounds including hormones, serving as a source of nutrients for sperm development and maturation, protecting them from infection and enabling them to overcome the immunological and chemical environment of the female reproductive tract. In thi...

Sexual size dimorphism (SSD) reflects sex-specific solutions to the allocation of energy among growth, reproduction and survival; however, the proximate mechanisms behind these solutions are still poorly known even in vertebrates. In squamates, sexual differences in body size used to be attributed to direct energy allocation to energetically demanding processes, largely to reproduction. In addi...

Gonadal hormones are important mediators of sexual and aggressive behavior in vertebrates. Recent evidence suggests that the peptide hormones arginine vasotocin (AVT) and its mammalian homologue arginine vasopressin (AVP) often critically mediate these gonadal hormone effects on behavior and have direct influences on behavioral variation. Behavioral differences between sexes, across reproductiv...