Repro - Embryology (Genital Embryology) Flashcards
Pg. 561-562 Sections include: -Genital embryology -Bicornuate uterus -SRY gene -Male/female genital homologs Congenital penile abnormalities -Descent of testes and ovaries
What is the default gender development?
Female
What embryological changes occur in preparation for female development?
Mesonephric duct degenerates and paramesonephric duct develops
What gene determines male development? Where is it found? What is its gene product, and what effect does this have?
SRY gene on Y chromosome - produces testis-determining factor (testes development)
What substance do Seroli cells produce, and what effect does this substance have on genital development?
Sertoli cells secrete Mullerian inhbitiory factory (MIF) that suppresses development of paramesonephric duct
What substance do Leydig cells produce, and what effect does it have on genital development?
Leydig cells secrete androgens that stimulate the development of mesonephric ducts
What is another name for the paramesoneprhic duct? Into what structures does it develop?
Paramesonephric (Mullerian) duct; Develops into female internal structures - fallopian tubes, uterus, and upper portion of vagina (lower portion from urogenital sinus)
What gives rise to the upper versus lower portions of the vagina?
Paramesonephric (Mullerian) duct - upper portion of vagina (lower portion from urogenital sinus)
How may Mullerian duct abnormalities present?
Mullerian duct abnormalities result in anatomical defects that may present as primary amenorrhea in females with fully developed secondary sexual characteristics (indicator of functional ovaries)
What is another name for the Mesonephric duct? Into what structures does it develop?
Mesonephric (Wolffian) duct; Develops into male internal structures (except prostate) - Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens (SEED).
What causes Bicornuate uterus? How does it differ from double uterus and vagina?
Results from incomplete fusion of the paramesonephric ducts (vs. complete failure of fusion, resulting in double uterus and vagina).
What medical complication can result from Bicornuate uterus, and why?
Can lead to anatomic defects => recurrent miscarriages
What characterizes a patient that has SRY gene on Y chromosome but no Sertoli cells?
No Sertoli cells or lack of Mullerian inhibitory factor: develop both male and female internal genitalia and male external genitalia
What characterizes a patient that has SRY gene on Y chromosome but 5alpha-reductase deficiency?
5alpha-reductase deficiency: male internal genitalia, ambiguous external genitalia until puberty (when high testosterone levels cause masculinization)
Diagram the process of male genital development, including the effects of the following key players: (1) SRY gene on Y chromosome (2) Sertoli cell (3) Leydig cell.
See p. 561 in First Aid 2014 for diagram at bottom of page
How are internal versus external male genitalia normally generated?
Testosterone converts Wolffian duct to male internal genitalia (except prostate); DHT converts genital tubercle/urogenital sinus to male external genitalia/prostate
What secretes Mullerian inhibitory factor, and what role does it play?
Sertoli cells; Degeneration of paramesonephric (Mullerian) cut (female internal genitalia)
Draw and label the following genital embryology structures: (1) Gubernaculum (2) Indifferent gonad (3) Mesonephros (4) Mesonephric duct (5) Paramesonephric duct (6) Urogenital sinus.
See p. 561 in First Aid 2014 for visual at top right of page
What is the fate of the Genital tubercle in the presence of estrogen versus dihydrotestosterone?
ESTROGEN: Genital tubercle => Glans clitoris & Vestibular bulbs; DIHYDROTESTOSTERONE: Genital tubercle => Glans penis & Corpus cavernosum and spongiosum
What is the fate of the Urogenital sinus in the presence of estrogen versus dihydrotestosteronee?
ESTROGEN: Urogenital sinus => Greater vestibular glands (of Bartholin) & Urethral and paraurethral glands (of Skene); DIHYDROTESTOSTERONE: Urogenital sinus => Bulbourethral glands (of Cowper) & Prostate gland
What is the fate of the Urogenital folds in the presence of estrogen versus dihydrotestosterone?
ESTROGEN: Urogenital folds => Labia minoria; DIHYDROTESTOSTERONE: Urogenital folds => Ventral shaft of penis (penile urethra)
What is the fate of the Labioscrotal swelling in the presence of estrogen versus dihydrotestosterone?
ESTROGEN: Labioscrotal swelling => Labia majora; DIHYDROTESTOSTERONE: Labioscrotal swelling => Scrotum
What are 4 key parts of undifferentiated genitals? What determines their differentiation into female versus male genitals?
(1) Genital tubercle (2) Urogenital sinus (3) Urogenital folds (4) Labioscrotal swelling; Dihydrotestosterone (male) versus Estrogen (female)
What are 2 types of congenital penile abnormalities?
(1) Hypospadias (2) Epispadias
What is hypospadias? Where is it located? What causes it?
Abnormal opening of penile urethra on inferior (ventral) side of penis due to failure of urethral folds to close; Think: “Hypo is below”
What is epispadias? Where is it located? What causes it?
Abnormal opening of penile urethra on superior (dorsal) side of penis due to faulty positioning of genital tubercle; Think: “when you have Epispadias, you hit your Eye when you pEE”
Of hypospadias and epispadias, which is more common?
Hypospadias is more common than epispadias
What is of medical concern for hypospadias?
Fix hypospadias to prevent UTIs
What condition is associated with epispadias?
Exostrophy of the bladder is associated with Epispadias
What 2 structures are related to the descent of the testes and ovaries?
(1) gubernaculum (2) processus vaginalis
What is the gubernaculum?
Gubernaculum (band of fibrous tissue)
What is the processus vaginalis?
Processus vaginalis (evagination of peritoneum)
Briefly describe the gubernaculum remnant in males versus females.
MALE REMNANT: Anchors testes within scrotum; FEMALE REMNANT: Ovarian ligament + Round ligament of uterus
Briefly describe the processus vaginalis in males versus females.
MALE REMNANT: Forms tunica vaginalis; FEMALE REMNANT: Obliterated
