Normal and abnormal sexual development ppt

C h a p t e r Normal and abnormal sexual development and puberty Sexual differentiation Genetic sex Abnormal development 21 21 22 Puberty Common clinical presentations and problems 26 27 O V E R V I E W Sexual differentiation and normal subsequent development are fundamental to the continuation of the human species In recent years, our understanding of the control of this process has greatly increased Following fertilization, the human embryo will differentiate into a male or female fetus, and subsequent development is genetically controlled This chapter describes the processes involved and discusses the subsequent evolution to full maturation Sexual differentiation The means by which the embryo differentiates is controlled by the sex chromosomes This is known as fenetic sex The normal chromosome complement is 46, including 22 autosomes derived from each parent An embryo that contains 46 chromosomes and has tr.e sex chromosomes XY will develop as a mate If the M chromosomes are XX, the embryo will differentiJie into a female The resulting development of the gonad will create either a teslis or an ovary This is known as gonaclal sex Subsequent development of *e internal and external genitalia gives phenotypic ^- i>r the sex ol appearance Cerebral differen•arion to a male or female orientation is known as Genetic sex hi the developing embryo with a genetic complement of 46 XY, it is the presence of the Y chromosome that determines that the undifferentiated gonadwill become a testis (Fig 3.1) Absence of the Y chromosome will result in the development of an ovary On the short arm of the Y chromosome is a region known as the SRI' gene, which is responsible for the determination of testicular development as it produces a protein known as testicular determining factor (TDF) TDF dircc influences the undifferentiated gonad to become ; testis When this process occurs, the testis abt Miillerian inhibitor The imdifferentiated embryo contains b and Miillerian ducts The Wolffian du 22 Normal and abnormal sexual development and puberty Un differentiated gonad Undiflerentiated gonad iJTDF Testis Ovary Sertoli cells Leydig cells V Mullerian inhibitor Testosterone 5areductase Wolffian development Mullerian regression No Mullerian inhibitor Vas deferens Epididymis Seminal vesicles Dihydrotestosterone Penis Scrotum Miillerian development No testosterone Wolffian regression Uterus Fallopian tubes Cervix Vagina Figure 3.2 Female differertialion (TOP, testicular determining factor.) Figure 3.1 Male differentiation (TDF testicular determining factor.) potential to develop into the internal organs of the male, and the Mullerian ducts into the internal organs of the female If the testis produces Mullerian inhibitor, the Miillerian ducts regress The testis differentiates into two cell types, Leydig cells and Sertoli cells The Sertoli cells are responsible for the production of Mullerian inhibitor, which leads to Mullerian regression The Leydig cells produce testosterone, which promotes the development of the Wolffian duct, leading to the development of vas deferens, the epididymis and the seminal vesicles Testosterone by itself does not have a different effect on the cloaca; in order to exert its androgenic effects, it needs to be converted by the cloacal cells through the enzyme 5