female reproduction 2

• MIS

  Mullerian inhibiting substance
• SRY gene

  Sex determining region Y
• SRY gene is detected in the bipotential gonad of XY individuals at about 42 days of fertilization
• SRY gene is found on the Y chromosome
• Sex-determining region Y protein


  Acts as a transcription factor, which binds to specific regions of DNA and starts processes that cause a fetus to develop male gonads (testes) & prevent the development of female reproductive structures (uterus and fallopian tubes)
• Mullerian inhibiting factor (MIF) / anti-Mullerian hormone (AMH)


  Plays a significant role in sexual differentiation. It is produced by the Sertoli cells in male fetuses (stimulated by FSH) & signals the regression of the Mullerian ducts, fallopian tubes, and uterus
• Androgens (testosterone)

  Induce differentiation of Wolffian ducts or mesonephric duct into male internal epididymis, seminal vesicle, vas deferens and external genitalia
• Dihydrotestosterone


  Induces the differentiation of external male genitalia such as the prostate and penis
• Aberrant sexual differentiation

  • Due to genetic abnormalities
  • Due to non specific teratogenic influences
  • Due to hormonal abnormalities
• Male pseudohermaphroditism

  The development of female external genitalia in genetic males
• Defective testicular development

  Genetic males with defective testes have female internal genitalia
• Androgen resistance


  Male hormones cannot exert their full effects on the tissues due to various congenital abnormalities
• Female pseudohermaphroditism


  Male genital development (hypertrophy of clitoris) in genetic females exposed to androgens from some other source during the 8th to the 13th weeks of gestation
• Puberty

  The period when the endocrine & gametogenic functions of the gonads have first developed to the point where reproduction is possible
• Thelarche


  The development of breasts
• Pubarche

  The development of axillary and pubic hair
• Menarche


  The first menstrual period
• Initial menstrual periods are generally anovulatory, and regular ovulation appears about a year later
• In children between the ages of 7 and 10, a slow increase in estrogen & androgen secretion precedes the more rapid rise in the early teens
• Females- age of puberty 8-13years, Males- 9-14 years
• Hypothalamic-pituitary-gonadal (HPG) axis


  The physical changes of puberty are initiated by the activation of this axis
• GnRH

  Gonadotropin-releasing hormone, its pulsatile release triggers the first hormonal change in puberty
• LH


  Luteinizing hormone, stimulates the theca cells in the ovary to produce estrogen precursors and the Leydig cells of the testes to produce testosterone
• FSH

  Follicle-stimulating hormone, works on the ovarian follicle to convert the thecal estrogen precursors to estrogen and on the Sertoli cells in the seminiferous tubules of the testes to help create sperm
• Precocious pseudopuberty


  Early development of secondary sexual characteristics without gametogenesis, caused by abnormal exposure of immature males to androgen or females to estrogen
• True precocious puberty

  Due to an early but otherwise normal pubertal pattern of gonadotropin secretion from the pituitary
• Adrenarche


  The increase in the secretion of adrenal androgens at the time of puberty, which leads to the development of pubic and axillary hair
• Dehydroepiandrosterone (DHEA)


  Adrenal androgen that peaks at about age 25 in women and slightly later in men, then declines slowly to low values in old age
• Tanner Staging- Sexual Maturity Rating (SMR)


  A system to track the development & sequence of secondary sex characteristics of children during puberty
• Tanner Stages

  • Stage 1 (prepubertal)
  • Stage 2
  • Stage 3
  • Stage 4
  • Stage 5
• Peak height velocity occurs at 13.5 years in boys and 11.5 years in girls
• Adrenarche occurs at age 8–10 years in girls and age 10–12 years in boys
• Menarche (first menstrual period) occurs at an average age of 12.7 years
• Precocious sexual development


  Abnormal early development of sexual characteristics
• Critical weight and leptin

  A critical body weight must normally be reached for puberty to occur, and leptin may be the link between body weight and puberty
• Delayed or absent puberty


  Pathological delay in the onset of puberty
• Panhypopituitarism


  Associated with dwarfing & evidence of other endocrine abnormalities
• Eunuchoidism


  Delayed puberty in males with normal gonads and other endocrine functions
• Primary amenorrhea


  Delayed puberty in females with normal gonads and other endocrine functions
• Number of primordial follicles per ovary declines with age, leading to menopause