Puberty in Non-human Primates and Man

Neuroendocrine control of the onset of puberty

“…It is now generally accepted that the hypothalamic GnRH pulse generator drives “basal” or “tonic” gonadotropin secretion that is responsible for folliculogenesis, maintenance of the corpus luteum and the synthesis of ovarian estradiol and progesterone in the female and for maintaining spermatogenesis and testicular testosterone secretion in the male [13]. An additional mode of gonadotropin release, the pre-ovulatory LH surge observed at the end of the follicular phase of the ovarian cycle, is required for ovulation and therefore for puberty in the female [13].…”

“…An additional mode of gonadotropin release, the pre-ovulatory LH surge observed at the end of the follicular phase of the ovarian cycle, is required for ovulation and therefore for puberty in the female [13]. In all species, the GnRH pulse generator plays an important role in producing the surge mode of gonadotropin release because it drives the rise in estradiol secretion late in the follicular phase that in turn serves as the ovarian component of the trigger for the pre-ovulatory LH surge.…”

“…There are two primary reasons for this. First, puberty in these species occurs after a protracted period of relatively stable gonadal quiescence during infancy and juvenile development 2 [13]. Therefore in primates the onset of puberty is clearly demarcated from earlier embryonic and perinatal periods of pre-pubertal development.…”

“…Therefore in primates the onset of puberty is clearly demarcated from earlier embryonic and perinatal periods of pre-pubertal development. For example, in the male monkey, the appearance of differentiating spermatogonia, which is an early event of male puberty marking the initiation of spermatogenesis, is not typically observed until 36 months of age [13]. In the mouse on the other hand differentiating spermatogonia appear in the testis as early as postnatal day 3 [14].…”

Daily successive changes in reproductive gene expression and neuronal activation in the brains of pubertal female mice

“…The onset of puberty is generally defined as the activation of the previously-dormant neuroendocrine reproductive axis (Grumbach, 2002; Ojeda and Skinner, 2006; Plant and Witchel, 2006), reflected by increased secretion of gonadotropin-releasing hormone (GnRH). Several upstream hypothalamic circuits have been implicated in the control and modulation of GnRH secretion, but how and when these various reproductive circuits change during development to potentially time and trigger pubertal GnRH secretion is poorly understood (Kauffman, 2010; Ojeda et al, 2006, 2010; Richter, 2006; Tena-Sempere, 2012; Terasawa et al, 2013).…”