Repro Development Flashcards
What embryological layer does the urogenital system arise?
Intermediate mesoderm
When is genetic sex determined?
At fertilization
SRY gene produces what protein? What is its importance?
Testis-determining factor and thus the development of the testes
Testis-determining factor is responsible for the cords differentiating into what?
Seminiferous tubules
What is the most common abnormality of sexual differentiation?
Klinefelt syndrome
What is the karyotype for Klinefelter syndrome?
47, XXY
Klinefelter syndrome usually arises due to what?
Non-dysjunction of the XX homologues
What are the patient characteristics in Klinefelter syndrome?
Infertility, Gynecomastia, Impaired sexual maturation (Atrophic testes, Small penis, Lack of secondary male characteristics)
What is the karyotype of Turner syndrome?
45, XO
What are the patient characteristics of turner syndrome?
Short stature, High arched palate, Webbed neck, Shield-like chest, Inverted nipples, Cardiac (bicuspid aortic valve) and renal anomalies
What is the disorder of sex development?
Ovotesticular disorder (true hermaphrodites)
The caudal part of the genital ridge gives rise to what?
The gonads
The developing gonads consist of what cells?
Mesothelium (coelomic epithelium), underlying mesenchyme, and primoridal germ cells
Describe the migration of gametes during the early indifferent stage of sexual development.
Gametes migrate from the umbilical vesicle (yolk sac) into the genital (gonadal) ridge
The primordial germ cells undergo what genetic events during migration?
Mitoses
In the male the cortical cords form what structures?
Seminiferous tubules, tubuli recti (straight tubules), and rete testis; and serve as precursors of the sustentacular cells of Sertoli
In the male and female, what cells migrate into the cortical cords?
Primordial germ cells migrate from the umbilical vesicle
What do the interstitial cells of Leydig develop from?
Mesenchyme
The sustentacular cells of Sertoli are responsible for what in regards to development?
Under the influence of hCG, Sertoli cells produce anti-mullerian hormone - suppresses the development of paramesonephric (mullerian) ducts
Oogonia undergo what genetic process?
Mitosis, to produce numerous oogonia
Leydig cells produce what?
Androgenic hormones (testosterone and androstenedione)
The cells form primordial follicles?
Follicular cells and oogonia
How do we get primary oocytes?
Oogonia, under the influence of meiosis-stimulating factor, enter prophase I of meiosis and become primary oocytes
What happens to the oocytes during ovulation?
Primary oocyte continues with meiosis, becoming a secondary oocyte in metaphase II of meiosis until fertilization
What stage are primary oocytes arrested in?
Prophase I until ovulation
What stage are secondary oocytes arrested in?
Metaphase II until fertilization
The indifferent sexual duct system consists of what two duct structures?
Mesonephric (Wolffian) ducts and paramesonephric (Mullerian) ducts
What happens to the caudal end of the paramesonephric ducts?
Fuse and terminate on the urogenital sinus between the ends of the mesonephric ducts as the uterovaginal primordium
How is the uterovaginal primordium formed?
The caudal ends of the paramesonephric ducts fuse and terminate on the urogenital sinus
In males, the anti-mullerian hormone causes what?
Paramesonephric mullerian ducts to degenerate, leaving only the the prostatic utricle
What cells produce testosterone in a male fetus?
Cells of Leydig
What effect does testosterone have on the male fetus/development?
Causes the mesonephric duct to become the epididymis, ductus deferens, and ejaculatory duct
Under the influence of testosterone, the mesonephric duct forms what?
Epididymis, ductus deferens, and ejaculatory duct
How do the seminal vesicles develop?
As an outgrowth of the ductus deferens
The part of the mesonephric duct (ductus deferens) between the duct of the seminal vesicle and urethra becomes what?
Ejaculatory duct
What does the prostate gland develop from?
Epithelial outgrowth of the pelvic portion of the urogenital sinus
Bulbourethral glands develop from what?
Epithelial outgrowth of the spongy urethra (derived from the phallic portion of the urogenital sinus)
How does the absence of anti-mullerian hormone effect development?
Allows the paramesonephric duct to develop into the uterine tubes and uterus
What forms the sinus tubercle?
The uterovaginal primordium projecting into the dorsal wall of the urogenital sinus
The uterine tubes develop from what?
Cephalic, un-fused portion of the paramesonephric duct
What does the uterus develop from?
The caudal, fused portion of the paramesonephric duct
How is the vagina developed?
Upper 1/3 from the paramesonephric duct; lower 2/3 from urogenital sinus
The bulbourethral glands in the male are homologous to what female structures?
Greater vestibular glands
The greater vestibular glands in the female are homologous to what male structure?
Bulbourethral glands
What happens to the mesonephric ducts in a female?
Regress due to lack of testosterone (but may be found outside the uterus and vagina as Gartner’s duct)
Gartner’s ducts are found in a phenotypically normal female. These ducts are remnants of what?
The mesonephric duct
The paramesonephric duct gives rise to what structures?
Uterine tubes, uterus, cervix, and upper 1/3 of vagina
What are signs and symptoms of paramesonephric duct agenesis?
Complete/partial absence of uterine tubes, uterus, cervix and vagina; normal secondary sex characteristics, ovaries are intact and ovulation usually occurs without menstrual cycle (primary amenorrhea)
How could a double uterus or double vagina form?
Paramesonephric duct fails to fuse and each develops into a separate uterus
How does a uterine septum form?
Incomplete resorption of tissue in developing uterus
Absence of uterus and vagina is due to what development defect?
Failure of uterovaginal primoridum to form, and to induce formation of the sinus tubercle
The trans-abdominal descent refers to what?
Testes descends to the deep inguinal ring due to differential growth
What is responsible for the movement through the inguinal canal and into the scrotum?
Testosterone
What is the trans-inguinal descent?
Movement of the testes through the inguinal canal and into the scrotum
The gubernaculum of the testes connects what two structures?
The caudal pole of the testes to the labioscrotal fold
The process vaginalis forms what in the male?
Tunica vaginalis
In the female, the gubernaculum develops into what?
Ligament of the ovary and the round ligament of the uterus
What is cryptorchidism?
Undescended testes
Cryptorchidism results in what? And can increase risk of what?
Results in sterility and a higher incidence of cancer if present in the abdominal cavity
How does an ectopic testis develop?
Because of an abdominal location of the gubernaculum, other than the labioscrotal fold
How does a congenital inguinal hernia develop?
Results when peritoneal canal fails to close (persistent vaginal process)
What structure forms the efferent ductules?
The mesonephric ductules
The genital tubercle develops into what?
The phallus
What does the phallus develop from?
From the genital tubercle
The urorectal septum divdies the cloacal membrane into what?
Dorsal anal membrane and ventral urogenital membrane
What divides the cloacal membrane into a dorsal epithelial plug and a ventral urogenital membrane?
Urorectal septum
What enzyme converts testosterone to dihydrotestosterone?
5alpha-reductase
How does the phallus become the penis?
Masculinization due to dihydrotestosterone effects on the phallus
Urogenital folds (urethral folds) fuse to form what?
Spongy urethra
What forms the spongy urethra?
Urogenital folds (or urethral folds) fusing
What is the penile raphe?
Linfe of fusion of the surface ectoderm on the ventral surface of the penis
The corpora cavernosa penis develops from what?
Mesenchyme of phallus
Corpus spongiosum penis develops from what?
Mesenchyme of phallus
What forms the scrotum?
Labioscrotal swellings
Male pseudohermaphrodite has what genotype?
46, XY DSD
Male pseudohermaphrodite may be due to what?
Inadequate amount of testosterone or Mullerian inhibiting substance
What is hypospadias?
Male urethra opens on the ventral (perineal) surface of the penis
Hypospadias is due to failure of what?
Failure in fusion of the urogenital folds; or failure of epithelial cord to join with the spongy urethra
What is epispadias?
Male urethra opens on the dorsal surface of the penis
Epispadias is associated with what other abnormality?
Exstrophy of the bladder
In a female, the phallus becomes what?
Clitoris
Feminization of the external genitalia in a female fetus is a result of what?
Estrogens produced by the placenta and maternal ovaries and lack of testosterone
In the female, the urogenital folds become what?
The labia minora
What are the labia minor formed from?
Urogenital folds (they do not fuse)
What form the labia majora?
Labioscrotal swellings
Congenital adrenal hyperplasia can result in female pseudohermaphrodite, what is the genotype?
46, XX
In female pseudohermaphrodites, what is the “sex” of the internal organs?
Typcially female
What happens to a 46,XX individual with congenital adrenal hyperplasia?
Fetal adrenal glands produce excessive androgenic hormones, resulting in masculinization of the external genitalia; internal organs remain female typically
Androgen insensitivity syndrome appears in individuals with what genotype?
46, XY
In androgen insensitivity syndrome, what is defective?
Androgen receptors due to point mutation
What is the phenotype of an individual with androgen insensitivity syndrome?
Normal female external phenotype, but possess internal testes
The genital ridge forms what homologous derivatives?
Male: testis; female: ovary
The indifferent structure, the sex cords, produce what homologous derivatives?
Male: seminiferous tubules; female: follicular cells
The genital tubercle produces what homologous derivatives?
Male: penis; female: clitoris
The urogenital folds produce what homologous structures?
Male: floor of penile urethra; female: labia minora
The genital swellings produce what homologous structures?
Male: scrotum; female: labia majora
