Puberty

1. Puberty The ability to accomplish reproduction successfully Dependant on: Development of a threshold body size Exposure to social and environmental cues Genetics of the animal Puberty is a transition from prepubertal to postpubertal that may last for weeks or months “The fundamental requirement for pubertal onset is the secretion of GnRH at the appropriate frequency and quantities to stimulate Gonadotropin release by the anterior pituitary lobe”

3. Development of the Surge Center in the female and defeminization in the male

5. Changes in Hypothalamic sensitivity Prepubertal female Low frequency GnRH pulses from the tonic center result in low stimulation of estradiol resulting in insufficient stimulation of the surge center Postpubertal female Higher frequency GnRH pulses from the tonic center result in stimulation of estradiol above threshold concentrations to stimulate the surge center resulting in the preovulatory LH surge Prepubertal male GnRH is very sensitive to negative feedback of testosterone/estrogen Postpubertal male Decreased GnRH sensitivity to negative feedback results in more GnRH released producing greater concentrations of testosterone/estrogen

7. End Points to determine the age of puberty Female Age at first estrus Age at first ovulation Age at which the female can successfully support a pregnancy Male Age when behavioral traits are expressed Age at first ejaculation Age at first spermatozoa in the ejaculate Age at first spermatozoa in the urine Age when ejaculate has a threshold number of spermatozoa

8. Factors that influence the age of puberty Body Size and Degree of Fatness

10. Factors that influence the age of puberty Body Size and Degree of Fatness External and social factors Genetics