ENDOCRINOLOGY OFTHE REPRODUCTIVE SYSTEM

INTRODUCTION

M. Djauhari WidjajakusumahFakultas Kedokteran Universitas Indonesia

REPRODUCTIVE SYSTEM

Maintaining the continuity of the species

Asexual reproduction:forming new offspring that does not involve the union of two gameteslower animals, microorganisms, plants

Sexual reproduction:involves fundamental processes: gametogenesis & fertilizationgametes have half the normal chromosomes

GONADS

Dual function:GametogenesisSex hormones: androgens and estrogensInhibin: inhibition of FSH secretion

TestesLarge amounts of androgens (testosterone)Small amounts of estrogens

OvariesLarge amounts of estrogens Small amounts of androgensProgesteroneRelaxin (particularly in pregnancy)

Figure 46-2 Development of the human male reproductive organs and tract. Note the dependence on SRY, a gene on the Y chromosome that expresses the testis-determing factor, and on hormone products of the gonad (testosterone , dihydrotestosterone, and anti-Mllerian hormone [AMH]). 20072007Testis Determining Factor

SEX DIFFERENTIATION

Determined genetically by sex chromosomes (X & Y)

Y chromosome:necessary for the production of testestestis-determining gene product: Sex-determining Region of Y chromosome testicular differentiation fetal testis: testosterone (Leydig) mullerian inhibiting substance / MIS (Sertoli) under the influence of hCG

DEVELOPMENT OF THE GONADS

Primitive gonad --> indifferent gonad (cortex and medulla)

Genetic males (7th week):the medulla of indifferent gonad --> testis Leydig and Sertoli cells appearTestosterone and MIS secretedcortex regresses

Genetic femalesthe cortex of indifferent gonad --> ovaryembryonic ovary does not secrete hormonesmedulla regresses

Pseudo-hermaphroditism: Hormonal Abnormalities

Pseudohermaphrodite

individual with the genetic constitution and gonad of one sex, and the genitalia of the other

Female pseudohermaphroditism

male genital development in genetic femaleandrogens exposure during 8th-13th week of gestationcongenital virilizing adrenal hyperplasiaandrogens administered to the mother

Pseudo-hermaphroditism: Hormonal Abnormalities

Male pseudohermaphroditism

The embryonic testes are defective

development of female external genitalia in genetic malesdeficient in MIS female internal genitalia

Androgen resistance

male hormones can not exert their full effects on the tissue5alpha-reductase deficiency dihydrotestosterone decreased female external genitaliamutation in the androgen receptor gene

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