Severson: Normal and Abnormal Reproductive Development Flashcards
origin of urogenital system
intermediate mesoderm
origin of urinary system
nephrogenic ridge
origin of genital system
Gonadal/genital ridge
determined at the time of fertilizatin
genetic sex
When does phenotypic/genital sex of embryo manifest?
7th week
what leads to the development of the testes?
SRY on Y chromosome produces TDF leading to the development of the testes
what determines phenotypic malenness?
testes
what’s required for development of female phenotype?
two X chromosomes
responsible for cortical cords differentiating into seminiferous tubules
testis-determining factor
produced by fetal testes> determines maleness
testosterone
47,XXY
Klinefelter syndrome
MC abnormality of sexual differentiation d/t nondisjunction of XX homologues
Klinefelter syndrome
infertility, gynecomastia and impaired sexual maturation
Klinfelter syndrome
45, XO
Turner Syndrome
Failure of gonads to develop and infantile genitalia d/t lack of PATERNAL sex chromosome
Turner syndrome
short stature, high arched palate, webbed neck, broad and shieled like chest, wide spaces and inverted nipples, absence of sexual maturation, lymphedema of hands and feet, cardiac and renal anomalies
Turner Syndrome
46, XX
DSD- Ovotesticular disorder (true hermaphrodites)
Possess both testicular and ovarian tissue
migrate from the UMBILICAL VESICLE into the GENITAL RIDGE during early indifferent stage of sexual development
gametes
enter the GENITAL RIDGE during the latter part of the 5th week of development
primordial germ cells
Gives rise to gonads
caudal part of genital ridge
What do the developing gonads consist of?
mesothelium (coelomic), underlying mesenchyme and primordial germ cells
Migrates into the cortical cords
Primordial germ cells
M vs. F migration of germ cells into cortical cords
M> forms seminiferous tubules
F> cords break apart> form follicular cells that surround germ cells
these cells originiate in the UMBILICAL VESICLE then migrate along the dorasal mesentery of hte hindgut to the GENITAL RIDGE undergoing MITOSIS while they migrate
primordial germ cells
precursors of sertoli cells (mesothelium)
Cells of cortical cords
forms the seminiferous tubules, tubuli recti and rete testis
cortical cords
becomes the efferent ductules
mesonephric duct
what part of the mesonephric duct becomes the epidiymis
distal portion
these cells develop from MESENCHYME and synthesize androgenic hormones that are necessary for the differentiation of the male sexual duct system and external genitalia
Leydig cells
stimulates leydig cells to produce androgenic hormones
hCG
when do leydig cells reappear?
puberty
produces anti-mullerian hormone when stimulated by hCG
sertoli cells
suppresses development of paramesonephric ducts
anti-mullerian hormones
stimulates oogonia to enter PROPHASE I of meisosis and become primary oocytes
Meiosis stimulating factor
indifferent sexual duct system
mesonephric (wolffian) duct
paramesonephric (mullerian) duct
ureterovaginal primordium
caudal ends of the PARAMESONEPHRIC DUCTS fuse and terminae on the urogenital sinus between the ends of the mesonephric ducts forming the ureterovaginal primordium
AMH (from sertoli cells) causes mullerian ducts to degenerate leaving…
prostatic utricle and appendicx of the testis
Causes the mesonephric ducts to become the epididymis, ductus deferens and ejaculatory duct
Testosterone from leydig cells
develop as an outgrowth of the ductus deferens
seminal vesicles
What becomes the ejactulatory duct?
part of mesonephric duct between the duct of hte seminal vesicle and urethra
epithelial outgrowth of the PELVIC PORTION OF HTE UROGENITAL SINUS into surrounding mesenchyme
prostate gland
mesenchyme forms stroma and SM of gland
develops as an epithelial outgrowth of the SPONGY URETHRA
bulbourethral glands
origin of spongy urethra
phallic portion of urogenital sinus
What happens to sexual ducts if ovaries are present or gonads are absent?
differentiate into female phenotype
What allows for the development of the uterine tubes and uterus
absence of AMH which allows paramesonephric ducts to develop into lady parts
What forms the uterovaginal primordium?
paramesonephric ducts pass cuadally in pelvic region approach each other and fuse
produced from the uterovaginal primordium projecting into the dorsal wall of the urogenital sinus
sinus tubercle
develops from cephalic, unfused portion of paramesonephric ducts
uterine (fallopian) tubes
develops from the caudal FUSED portion of paramesonephric ducts
uterus
origin of upper 1/3 of vagina
paramesonephric ducts (uterovaginal primordium)
origin of lower 2/3 of vagina
vaginal plate derived from the urogenital sinus
Why do mesonephric ducts regress in a female?
lack of testosterone
gartner’s duct
part of mesonephric duct vound outside uterus and vagina that didn’t regress
Third MC cause of primary amenorrhea
Paramesonephric duct agenesis d/t genetic mutation
Complete/partial absence of uterine tubes/uterus/cervix/vagina
Normal development of secondary sex characteristics
Intact ovaries and ovulation
normal ovarian cycle w/out mentral cycle
paramesonephric duct agenesis
double uterus/double vagina
paramesonephric ducts fail to fuse and each develops as a separate uterus
double uterus and single vaggina
only distal end of paramesonephric ducts fuse
bicornate uterus
defective fusion of paramesonephric ducts
uterine septum
incomplete resorption of tissue in the developing uterus
unicornuate uterus
only ONE paramesonephric duct develops
failure of uterovaginal primordium to form and to induce formation of the sinus tubercle
absence of uterus/vagina
extends from the caudal pole of the testes to the labioscrotal fold
gubernaculum
What influences the descent of hte testes through the deep inguinal ring through the inguinal canal and into the scrotum
androgens
becomes the tunia vaginalis
process vaginalis
gubernaculum in the female becomes:
ligament of the ovary
round ligament of the tuerus
Cryptochordisim
undescended testes
higher rate in premature males
> sterility and higher incidence of cancer if in abdominal cavity
Ectopic testis
d/t migration of testes to some other site b/c of abnormal location of gubernaculum
Congenital inguinal herina
peritoneal canal fails to close (persistent vaginal process)
Accumulation of fluid in remains of process vaginalis
hydrocele
Becomes the phallus
genital tubercle at cranial end of cloacal membrane
Where are the labioscrotal swellings and urogenital folds located?
on each side of cloacal membrane
Divides cloacal membrane into a dorsal anal membrane and a ventral urogenital membrane
Urorectal septum
STimulates phallus to enlarge and elongate to form the penis
testosterone
urogenital folds fuse to form the…
spongy urethra
forms the penile raphe…
line of fusion of the surface ectoderm on the ventral surface
grows in from the glans and connects w/ the spongy urethra
ectodermal cord
origin of copora cavernosa penis and corpus spongiosum penis
mesenchyme of phallus
What forms the scrotum?
labioscrotal swellings–line of fusion is the scrotal raphe
reduced masculine development of genitalia d/t genetic defect leading to an inadequate amt of TESTOSTERONE or MULLERIAN INHIBITING SUBSTANCE
male pseudohermaphrodite (DSD) 46, XY
Urethra opens on the VENTRAL surface of the penis rather than at the end of the glans d/t failure in fusion of hte UROGENITAL FOLDS or the ECTODERMAL CORD to join the spongy urethra
Hypospadias (DSD)
*often d/t inadquate androgen production
Urethra opens on the DORSAL surface of the penis
Epispadias
What is epispadias associated with?
exstrophy of the bladder
Becomes hte clitoris
phallus
form the labia majora
urogenital folds
space between the urogenital volds
vestibule of hte vagina
forms the labia majora
labioscrotal swellings fuse posteriorly to form the posterior labial comissure and anteirorly to form the anterior labial commissure and mons pubis
female internal organs but external genitalia is masculine d/t CAH of the fetal suprarenal gland producing excessive androgenic hormones and masculinization of the external genitalia
female pseudohermaphrodite
46,XX
Normal female external phenotype but has internal testes d/t POINT mutation in the sequence that codes for an androgen receptor
Androgen insensitivity syndrome
46, XY