Puberty

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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
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Development of the Surge Center in the female
and defeminization in the male
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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
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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
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Factors that influence the age of puberty
Body Size and Degree of Fatness
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Factors that influence the age of puberty
Body Size and Degree of Fatness
External and social factors
Genetics