Puberty February 17, 2019 puberty

Introduction Puberty is a period when Endocrine and gametogenic function of GONADS have developed to a point when REPRODUCTION IS POSSIBLE February 17, 2019 puberty

Introduction Age and time of onset of puberty Variable Between ages of 10 to 14 yrs General decline in age at which puberty occurs Occurs earlier in girls than in boys ( 1 or 2 yrs) February 17, 2019 puberty

Testosterone Levels at Various Ages Secretion occurs in male fetus before birth During neonatal period Some testosterone is secreted This is followed by period of quiescence (pre-pubertal) At puberty gonadotropins are secreted Activation of gonads Plasma Testosterone Pre- pubertal fetal Puberty Adult senescence neonatal February 17, 2019 puberty

Testosterone Levels at Various Ages At puberty gonadotropins are secreted Activation of gonads Final maturations of gonads occur Plasma Testosterone Pre- pubertal fetal Puberty Adult senescence neonatal February 17, 2019 puberty

In Females GnRH, pituitary gonadotropins and estrogens Secreted at low levels throughout childhood Follicle maturation and menstruation do not occur Female sex accessory organs remain non-functional February 17, 2019 puberty

Changes at Puberty in Girls Increase in release of GnRH Stimulation of ovarian follicle development Estrogen secretion Which induce changes in Accessory sex organs Secondary sex characteristics February 17, 2019 puberty

Changes at Puberty in Girls First event Development of breasts (the-larche) Followed by Pu-barche Development of axillary and pubic hairs Followed by menarche First menstrual periods Irregular An-ovulatory Regular ovulatory periods occur after about a yr February 17, 2019 puberty

In Boys Accelerated growth of testes Spermatogenesis sets in Interstitial cells Secrete testosterone Increase in growth of accessory organs of reproduction Epididymis, vas deferens, seminal vesicles, prostate, penis February 17, 2019 puberty

In Boys Secondary male characteristics occur Scrotal skin thicken Growth of hairs (face, trunk, axillae, pubic hair) Growth of larynx – change of voice Muscle mass Aggressiveness February 17, 2019 puberty

In Boys and Girls Adrenarche Increase in secretion of adrenal androgens Occurs at the age of 8 to 10 in girls 10 to 12 in boys February 17, 2019 puberty

In Boys and Girls Increase in secretion of adrenal androgens Occur without any change in secretion of cortisol or ACTH Probably due to change in enzyme system Pregnenolone channeled to androgen pathway ?? Or to secretion of adrenal androgen stimulating hormone (AASH) from the ant. Pit February 17, 2019 puberty

Control of Onset of Puberty Gonads of children can be stimulated by gonadotropins Their pituitaries contain gonadotropins Hypothalamus contain GnRH However gonadotropin are not secreted February 17, 2019 puberty

Onset of Puberty Leptin It appears there is Leptin is a hormone secreted by the hypothalamus Has the effects of Decreasing food intake Increase energy consumption It appears there is Critical body wt that must be attained For puberty to occur February 17, 2019 puberty

Leptin vs Onset of Puberty Young women athlete engaged in strenuous exercises Lose weight Stop menstruation Girls with anorexia nervosa If they start to eat and gain weight They start menstruation February 17, 2019 puberty

Leptin vs Onset of Puberty Experimental observations Obese mice that cannot make leptin are infertile Fertility is restored by injection of leptin However The exact role of leptin in the causation of onset of puberty not clear February 17, 2019 puberty

Precocious Puberty Occurs when signs Of sexual maturations appears before the age of 8 yrs in girls or 10 yrs in boys Term implies premature development of Adult pattern of sexual function February 17, 2019 puberty

Precocious Puberty Gonadal maturation occurs Pseudo-precocity Spermatogenesis and ovulation May be sufficient for procreation Pseudo-precocity Premature development of secondary sex characteristics Due to excessive gonadal steroid From gonadal or adrenal tumors February 17, 2019 puberty

Causes of Precocity In normal child The hypothalamic – Pituitary – gonadal axis is functional before puberty It is thought to be under inhibitory influences from other parts of the brain February 17, 2019 puberty

Causes of Precocity Sexual precocity occurs when Inhibition is released prematurely February 17, 2019 puberty