Overview Week 1-6 embryo is sexually indifferent genetically male and female embryos are phenotypically the same both male and female have mesonephric (Wolffian) ducts at this stage Week 7 sexual differentiation occurs Week 12 sex of embryo can be distinguished based on external genitalia Week 20 phenotypical differentiation is complete Male vs. Female Differentiation Mesonephric (wolffian) duct needs to be induced to develop by testosterone from the Leydig cells of testes forms male internal sexual organs: Seminal vesicles, Epididymis, Ejaculatory duct, Ductus deferens Paramesonephric (müllerian) duct default development but can be suppressed forms female internal sexual organs: fallopian tube, uterus, upper 1/3 of vagina (lower 2/3 from urogenital sinus) Female default phenotypic differentiation mesonephric duct degenerates and paramesonephric duct develops Male SRY gene (Y chromosome) produces testis-determining factor which is necessary for testes development testes gives rise to sertoli cells: produces Müllerian inhibitory factor suppressing the development of paramesonephric ducts leydig cells: produces androgens stimulating development of mesonephric ducts Male/Female Genital Homologues Dihydrotestosterone Results in Developement Common Precursor Estrogen Results in Development Glans penis Genital tubercle Glans clitoris Corpus cavernosum and spongiosum Genital tubercle Vestibular bulbs Bulbourethral glands (of Cowper) Urogenital sinus Greater vestibular glands (of Bartholin) Prostate gland Urogenital sinus Urethral and paraurethral glands (of Skene) Ventral shaft of penis (penile urethra) Urogenital folds Labia minora Scrotum Labioscrotal swelling Labia majora Female Genital Abnormalities Unicornate Uterus one paramesonephric fails to develop Bicornuate Uterus due to incomplete/partial fusion of the paramesonephric ducts associated with urinary tract abnormalities and infertility Uterus didelphys no fusion between the two paramesonephric ducts resulting in a "double uterus" Müllerian agenesis failure of paramesonephric ducts to develop resulting in abnormalities of the upper portion of the vagina, cervix, uterus, and fallopian tubes Male Genital Abnormalities Hypospadias failure of urethral folds to fuse resulting in opening of penile urethra on inferior side of penis susceptible to UTI's surgery is recommended for treatment Epispadias faulty positioning of genital tubercle resulting in penile urethra opening on superior side of penis associated with exstrophy of the bladder Cryptochidism failure of testes to descend into scrotum (undescended testes) testes can be found in inguinal canal or abdominal canal can lead to infertility if both are undescended observable within 3 months of birth Hydrocele processus vaginalis remains patent allowing fluid to flow in resulting in a fluid filled sac in the scrotum can differentiate from tumor by shining light through testes hydrocele allows light to flow through whereas a tumor does not
QUESTIONS 1 of 8 1 2 3 4 5 6 7 8 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.RP.17.4753) A 35-year-old female presents to her gynecologist complaining of vaginal discomfort. She reports that over the past two weeks, she has developed dyspareunia and feels as if there is a mass on the external aspect of her vagina. She is sexually active in a monogamous relationship. On physical examination, there is a 2 cm unilateral erythematous swelling on the right side of the posterolateral labia minora. Which of the following embryologic precursors gives rise to the most likely etiology of this patient's symptoms? QID: 108748 Type & Select Correct Answer 1 Paramesonephric duct 12% (30/243) 2 Genital tubercle 12% (29/243) 3 Urogenital sinus 22% (53/243) 4 Urogenital fold 35% (84/243) 5 Labioscrotal swelling 15% (37/243) M 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.EB.15.11) A 4-day-old healthy male infant is born with normal internal and external male reproductive organs. Karyotype analysis reveals a 46XY genotype. Production of what substance by which cell type is responsible for the development of the normal male seminal vesicles, epididymides, ejaculatory ducts, and ductus deferens? QID: 101905 Type & Select Correct Answer 1 Testis-determining factor; Sertoli cells 11% (26/244) 2 Testis-determining factor; Leydig cells 13% (32/244) 3 Testosterone; Sertoli cells 10% (24/244) 4 Testosterone; Leydig cells 39% (94/244) 5 Mullerian inhibitory factor; Sertoli cells 26% (63/244) M 1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.EB.12.36) A 22-year-old G2P1 female presents to the clinic at the beginning of her third trimester for a fetal ultrasound. The sonographer is unable to visualize any of the structures arising from the mesonephric duct. This infant is at risk for malformation of which of the following? QID: 101930 Type & Select Correct Answer 1 Fallopian tubes 9% (29/334) 2 Uterus 13% (43/334) 3 Upper 1/3 of vagina 16% (52/334) 4 Lower 2/3 of vagina 8% (27/334) 5 No malformation would be expected 54% (181/334) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (M1.EB.12.35) A newborn infant with karyotype 46, XY has male internal and external reproductive structures. The lack of a uterus in this infant can be attributed to the actions of which of the following cell types? QID: 101929 Type & Select Correct Answer 1 Leydig 28% (54/191) 2 Sertoli 65% (124/191) 3 Theca 3% (6/191) 4 Granulosa 3% (5/191) 5 Reticularis 0% (0/191) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic
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