Male reproductive cycle, hormones

Male and female sex hormones. Influence secondary sexual characteristics regulate female reproductive cycle. 

Reproductive behavior in fish is a phenomenon that is synchronized by chemical means.138-140 A fraction of the steroids that are involved in the internal development of oocytes are released by females into the environment, where they are encountered by males — detection of this steroid induces internal hormonal changes in males that bring about enhanced sperm production. At a later time in the reproductive cycle, prostaglandins in the female that are associated with the follicular rupture of mature egg cells are released. Upon detection of the appropriate prostaglandin, males begin mating behaviors that culminate in the release of gametes by both sexes. 

BPA is considered an endocrine disruptor chemical and, in chronic studies, induces production of vitellogenin in male fathead minnows (P. promelas) at concentrations of 640 and 1280pgl after 43 days and 160pgl after 71 days. Induction of vitellogenin is a process normally occurring only in female fish in response to estrogenic hormones during the reproductive cycle. 

Testosterone promotes muscle growth deepening of the voice the growth of body hair and other male secondary sex characteristics Testosterone is formed from cholesterol and IS the biosynthetic precursor of estradiol the principal female sex hormone or estrogen Estradiol is a key substance m the regulation of the menstrual cycle and the reproductive process It is the hormone most responsible for the development of female secondary sex characteristics... 

Hormonal patterns and their regulation are more complex in females than in males due to the female cycle, the fertilization process, gestation and lactation. All functions ofthe female reproductive system are under endocrine control and therefore can be disrupted by effects on the reproductive endocrine system. 

SAFETY PROFILE An experimental teratogen. Human reproductive effects in women by subcutaneous route mensttual cycle changes and other unspecified effects. Experimental reproductive effects. Used in the treatment of oligospermia and male infertiHty. See also LUTEINIZING HORMONE and other luteinizing hormone-releasing hormone entries. 

Female reproduction may be recognized to be complex because it has been studied in greater detail and many more aspects of the female reproductive system are defined than for the male. Certainly the female reproductive system is overtly more dynamic and, perhaps because of this dynamicism, more susceptible to physical, chemical, and emotional stressors. The discrete series of events of the ovarian cycle which requires precise coordination between the central nervous system, hypothalamus, and pituitary in order for gametogenesis and ovulation to take place provides the opportunity for environmental changes to adversely influence normal processes. If these events are delayed or altered appreciably, some form of short-term infertility will most likely result. When this is compared to the male, the relatively monotonous production of hormone and gametes is not as likely to be overtly influenced by short-term events. 

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