PUBERTY BY D S AROKOYO INTRODUCTION Puberty represent

PUBERTY BY: D. S. AROKOYO

INTRODUCTION • Puberty represent an important developmental stage in both males and females that is characterized by distinct physiological & structural changes • During reproductive embryogenesis, the primitive gonads differentiate into either testes or ovaries (determined by genetic composition) • Thereafter; ü Ovaries remain quiescent until adolescence (Female embryo) ü A burst of testosterone/MIS production occurs in the testes for genitalia embryogenesis (Male embryo) ü The testes then also become quiescent until adolescence

INTRO. CONT’D • In both genders at adolescent stage, the gonads are activated to final maturation by gonadotropins from pituitary gland • The period of this final maturation is called puberty • Puberty can therefore be defined as: ‘that period during development when the endocrine & gametogenic functions of the gonads is first developed to the point where reproduction is possible’

PHYSIOLOGICAL CHANGES IN PUBERTY • Age at puberty is variable from one environment to the other and between the two genders • Age at puberty has declined progressively; ü 1 -3 months decline per decade in the USA for the past 200 yrs • Average ages at puberty; ü 8 – 13 years in girls ü 9 – 14 years in boys • Events of puberty in girls (in order) include; ü Thelarche i. e. Breast development ü Pubarche i. e. Axillary & pubic hair growth ü Menarche i. e. First menstrual flow

• Other signs of puberty in girls include; ü Narrowing of the shoulder ü Broadening the hip region ü Redistribution of body fats to the breasts & buttock region ü Wider carrying angle in the upper limbs ü Typical female escutcheon (Flat-topped pubic hair), etc. NB: Initial cycles are generally anovulatory & regular ovulation usually starts after about one year • Events of puberty in boys include: ü Increasing intensity of facial hair growth & on the axilla, pubis & chest

Puberty in boys cont’d ü Enlargement of genitalia ü Hyperpigmented skin ü Deepening of the voice ü Increased occurrence of acne vulgaris (pimples) ü Aggressive, war-like character, etc. • Generally, Adrenarche occur in both sexes at about 8 -10 years of age. This is an increased secretion of adrenal androgen without corresponding increase in cortisol & ACTH level

CONTROL OF ONSET OF PUBERTY • Actual mechanism determining the onset is not clear • However, basic postulations include; ü Only a pulsatile release of Gn. RH from hypothalamus & pituitary gonadotropins can stimulate endocrine activities of the gonads ü During the period from childhood to puberty, a neural mechanism operates to prevent this pulsatile release of Gn. RH ü This neural mechanism is removed at puberty

ABNORMALITIES OF PUBERTY • The abnormalities of puberty can either be; ü Early or Precocious puberty ü Delayed or absent puberty PRECOCITY • This is said to occur when an individual experiences puberty at an age much earlier than the lower limit of the normal range for his/her population • There are 2 forms of sexual precocity; ü Precocious Pseudo-puberty ü True precocious puberty

• Precocious Pseudo-puberty is early development of 2⁰ sexual characteristics without gametogenesis. v Usually due abnormal exposure of immature male to androgens or immature female to estrogen • True precocious puberty is early development of 2⁰ sexual characteristics due to early but otherwise normal pubertal pattern of gonadotropin secretion from the pituitary v Usually accompanied by normal gametogenesis

CAUSES OF PROCOCITY • Causes of Precocious pseudo puberty include; ü Congenital virilizing adrenal hyperplasia ü Androgen secreting tumors (males) - Leydig cell tumor ü Estrogen secreting tumors (females) - Granulosa cell tumor ü Miscellaneous causes e. g. exogenous androgen/estrogen • Causes of true precocious puberty include; ü Can be constitutional ü Cerebral lesions involving posterior hypothalamus ü Brain tumors ü Infections & developmental abnormalities of cerebrum ü Gonadotropin independent precocity

DELAYED OR ABSENT PUBERTY • Delayed puberty is only diagnosed after menarche has failed to occur by age 17 years or failure of testicular development by age 20 years • Delayed puberty from pan-hypopituitarism is associated with dwarfism & other endocrine anomalies • Puberty is usually totally absent in gonadal dysgenesis (XO) • Puberty can be delayed in the presence of otherwise normal endocrine function. This is called eunochoidism (male) or primary amenorrhea (female)

FACTORS AFFECTING ONSET OF PUBERTY • Social factors e. g. Vandenberg effect • Historical shift • Genetic influence • Environmental factors • Hormones & Steroids (Pharmacological products) • Nutritional influence: ↑body fat ═ Signal for puberty onset • Obesity & Exercise • Illnesses • Stress & Social factors

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