Development of urogenital system Flashcards
Intermediate Mesoderm
Following intermediate mesoderm as it becomes ____
ovaries and testes as well and organs that associate with them
Intermediate Mesoderm
Following intermediate mesoderm as it becomes ovaries and testes as well and organs that associate with them
→ While nephrogenic regions are located within intermediate mesoderm, its surface differentiates into ___
genital ridge
Migration of Germ Cells
Primordial germ cells , which become the spermatozoa and oocytes, originate in the ___ but migrate to the yolk sac.
epiblast
Migration of Germ Cells
During the 4th week, they migrate along the ____ to reach the genital ridge in the 6th week.
allantois
Germ Cells Enter Intermediate Mesoderm
Primordial germ cells take up residence in mesoderm just deep to the genital ridge, region will become ____
medulla of gonads
Germ Cells Enter Intermediate Mesoderm
Epithelium lining intraembryonic coelom invades mesoderm to form ____
While occurring, nearby ducts approach developing gonads through their developing____
- primitive sex cords
- mesentery
Mesonephric and Paramesonephric Ducts
___ drains urine from mesonephric kidney prior to its regression
→ then becomes ducts and organs associated with testis
→ developing under the influence of testosterone
Mesonephric (Wolffian) duct
Mesonephric and Paramesonephric Ducts
Mesonephric (Wolffian) duct drains urine from___ prior to its regression
→ then becomes ducts and organs associated with testis
→ developing under the influence of testosterone
mesonephric kidney
Mesonephric and Paramesonephric Ducts
Mesonephric (Wolffian) duct drains urine from___ prior to its regression
→ then becomes ducts and organs associated with testis
→ developing under the influence of ___
testosterone
Mesonephric and Paramesonephric Ducts
____ involutes into intermediate mesoderm
→ open-ended and becoming ducts and organs associated with ovary
Paramesonephric (Müellarian) duct
Mesonephric and Paramesonephric Ducts
Paramesonephric (Müellarian) duct involutes into intermediate mesoderm
→ open-ended and becoming ____ (2)
ducts and organs associated with ovary
Mesonephric and Paramesonephric Ducts
In females, paramesonephric ducts remain open to ____ near the gonad
→ fusing into common body prior to entering posterior aspect of urogenital sinus
intraembryonic coelom (eventual peritoneal cavity)
Mesonephric and Paramesonephric Ducts
In males, mesonephric ducts closely associate with ____
→ entering urogenital sinus separately on each side
gonads
Early Development of the Testes
If embryo is genetically male (XY), Y chromosome will transcribe (1)______ and create (2)____
- the SRY gene
- testis-determining factor (TDF)
Early Development of the Testes
If embryo is genetically male (XY), Y chromosome will transcribe (1)______ and create (2)____
- the SRY gene
- testis-determining factor (TDF)
Early Development of the Testes
TDF induces proliferation of primitive sex cords, which invade developing testis to create ______
→ eventually forming rete testis and seminiferous tubules, which connect to nearby mesonephric ducts
medullary cords
Early Development of the Testes
TDF induces____, which invade developing testis to create medullary cords
→ eventually forming rete testis and seminiferous tubules, which connect to nearby mesonephric ducts
proliferation of primitive sex cords
Early Development of the Testes
TDF induces proliferation of primitive sex cords, which invade developing testis to create medullary cords
→ eventually forming ___ and ____, which connect to nearby mesonephric ducts
rete testis and seminiferous tubules
Early Development of the Testes
Thick epithelium on surface forms _____, which later creates septae that invade testis
tunica albuginea
Early Development of the Testes
→ identify
Early Development of the Testes
Factors transcribed downstream of TDF stimulate ____ and ___
formation of Sertoli (from medullary cord) and Leydig (from intermediate mesoderm) cells
Early Development of the Testes
Factors transcribed downstream of TDF stimulate ____ and ___
formation of Sertoli (from medullary cord) and Leydig (from intermediate mesoderm) cells
Early Development of the Testes
Factors transcribed downstream of TDF stimulate formation of
- Sertoli from ____
- Leydig cells from ___
- medullary cord
- intermediate mesoderm
Early Development of the Testes
Starting in the 8th week, Leydig cells produce____
testosterone
Early Development of the Testes
Starting in the 8th week, Leydig cells produce testosterone
→ Testosterone will induce further development of ____
mesonephric ducts
Early Development of the Testes
Starting in the 8th week, Leydig cells produce testosterone
→ Testosterone will induce further development of mesonephric ducts
→ testis-determining factor (TDF) also upregulates activity of __
antiMüllerian hormone (AMH)
Early Development of the Testes
Starting in the 8th week, Leydig cells produce testosterone
→ Testosterone will induce further development of mesonephric ducts
→ testis-determining factor (TDF) also upregulates activity of antiMüllerian hormone (AMH)
→ causing ___
active regression of paramesonephric ducts
Early Development of the Testes
Factors transcribed downstream of TDF stimulate ____ and ___
formation of Sertoli (from medullary cord) and Leydig (from intermediate mesoderm) cells
Mesonephric Ducts
Mesonephric ducts is connected to rete testis
→ becoming _____ (5)
- efferent ductules
- epididymis
- ductus deferens
- seminal vesicles
- ejaculatory ducts
Mesonephric Ducts
Small and variable ____ are also remnants of paramesonephric ducts
testicular appendages (appendix testis) or epididymal appendages
Mesonephric Ducts
Small and variable testicular appendages (appendix testis) or epididymal appendages are also ____
remnants of paramesonephric ducts
Male Reproductive Glands
____ and ____ develop from endoderm of urogenital sinus below urinary bladder
Prostate and bulbourethral glands
Male Reproductive Glands
Prostate and bulbourethral glands develop from_____ below urinary bladder
endoderm of urogenital sinus
Male Reproductive Glands
Prostate and bulbourethral glands develop from endoderm of urogenital sinus below ___
urinary bladder
Male Reproductive Glands
Mesonephric ducts gives rise to seminal vesicles, which combine with ductus deferens to create ejaculatory duct
→ site where ejaculatory ducts empty into urogenital sinus is ____
small remnant of paramesonephric ducts, prostatic utricle
Male Reproductive Glands
Mesonephric ducts gives rise to seminal vesicles, which combine with ductus deferens to create ___
→ site where ejaculatory ducts empty into urogenital sinus is small remnant of paramesonephric ducts, prostatic utricle
ejaculatory duct
Male Reproductive Glands
Mesonephric ducts gives rise to seminal vesicles, which combine with ductus deferens to create ejaculatory duct
→ site where ejaculatory ducts empty into ___ is small remnant of paramesonephric ducts, prostatic utricle
urogenital sinus
Early Development of Ovaries
Changes to gonads and ducts dictated by signals received (or not) from gonads themselves
If embryo is genetically female (XX), primitive sex cords will regress
→ epithelium on ovary will proliferate to produce ____
cortical cords
Early Development of Ovaries
Changes to gonads and ducts dictated by signals received (or not) from gonads themselves
If embryo is genetically female (XX), primitive sex cords will regress
→ epithelium on ovary will proliferate to produce cortical cords
→ become ______ that surround and support oocytes
follicular cells
Early Development of Ovaries
cluster of follicular cells and oocyte called____
primordial follicle
Early Development of Ovaries
High levels of ___ stimulate paramesonephric ducts to develop further
→ mesonephric ducts will regress
estrogens
Early Development of Ovaries
High levels of estrogens stimulate ____ to develop further
→ mesonephric ducts will regress
paramesonephric ducts
Further Development of Paramesonephric Ducts
Near ovary paramesonephric ducts become ____
oviducts (Fallopian tubes)
Further Development of Paramesonephric Ducts
Near ovary paramesonephric ducts become oviducts (Fallopian tubes)
→ and their fused body will become ___ (3)
uterus, cervix, and superior part of vagina
Further Development of Paramesonephric Ducts
→ identify
Further Development of Paramesonephric Ducts
Small remnants of mesonephric ducts may be found alongside female reproductive organs
→ these are ___ (3)
epoophoron, paroophoron, and Gartner’s **duct cysts**
Development of the Vagina
The urogenital sinus thickens to form ____ where it meets the fused paramesonephric ducts.
sinovaginal bulbs
Development of the Vagina
____ thickens to form sinovaginal bulbs where it meets the fused paramesonephric ducts.
The urogenital sinus
Development of the Vagina
The urogenital sinus thickens to form ____ where it meets the fused paramesonephric ducts.
sinovaginal bulbs
Development of the Vagina
The urogenital sinus thickens to form sinovaginal bulbs where it meets ____
the fused paramesonephric ducts.
Development of the Vagina
The urogenital sinus thickens to form sinovaginal bulbs where it meets the fused paramesonephric ducts.
→ Together, they form ___ that connects the uterus to the vestibule
a solid structure, the vaginal plate
Development of the Vagina
The urogenital sinus thickens to form sinovaginal bulbs where it meets the fused paramesonephric ducts.
→ Together, they form a solid structure, the vaginal plate that connects ____ to ___
the uterus to the vestibule
Development of the Vagina
The vaginal plate hollows out to create ___ (3)
the vagina, vaginal fornix, and hymen.
Early Development of the External Genitalia
External genitalia develop from____ as it wraps around body to create pelvis
somatic layer of lateral plate mesoderm
Early Development of the External Genitalia
External genitalia develop from somatic layer of lateral plate mesoderm as it wraps around body to create pelvis
Cloaca is covered by ___ and is surrounded by cloacal fold on each side
cloacal membrane
Early Development of the External Genitalia
External genitalia develop from somatic layer of lateral plate mesoderm as it wraps around body to create pelvis
Cloaca is covered by cloacal membrane and is surrounded by ____ on each side
cloacal fold
Early Development of the External Genitalia
As _____ separates urogenital sinus from rectum, cloacal folds are re-named anal and urethral folds; the latter surround urogenital membrane
urorectal septum
Early Development of the External Genitalia
As urorectal septum separates urogenital sinus from rectum
→ cloacal folds are re-named ___ and ___
anal and urethral folds
Early Development of the External Genitalia
As urorectal septum separates urogenital sinus from rectum
→ urethral folds surround ____
urogenital membrane
Early Development of the External Genitalia
(1)_____ develop laterally to urethral folds and (2)___ develops anteriorly
- Labioscrotal swellings
- genital tubercle
Early Development of the External Genitalia
Labioscrotal swellings develop laterally to ___ and genital tubercle develops anteriorly
urethral folds
Development of the Female External Genitalia
Both male and female external genitalia develop from the same starting structures but diverge as they are exposed to different _____ (2)
levels of estrogens or DHT
Development of the Female External Genitalia
in females, urethral folds remain separate and form____ on either side of vestibule
labia minora
Development of the Female External Genitalia
in females, urethral folds remain separate and form labia minora on either side of __
vestibule
Development of the Female External Genitalia
in females, urethral folds remain separate and form labia minora on either side of vestibule
→ urogenital membrane ruptures to allow ___ and ___ to reach vestibule
urethral and vaginal openings
Development of the Female External Genitalia
- Labioscrotal swellings remain separate, making ___ and ___
- genital tubercle becoming ____
- labia majora and part of mons pubis
- glans of clitoris
Development of the Male External Genitalia
In men, urethral folds zip together on midline and surround urethra
→ site of fusion is (1)_____; this effectively extends urethra toward (2)____, which is derived from genital tubercle
- penile raphe
- glans of penis
Development of the Male External Genitalia
Labioscrotal swellings become (1)___ as they enlarge, fuse, and receive descending testes
→ site of fusion along midline of scrotum is (2)___
- scrotum
- scrotal raphe
Development of the Male External Genitalia
Labioscrotal swellings become scrotum as they enlarge, fuse, and receive ___
→ site of fusion along midline of scrotum is scrotal raphe
descending testes
Development of the Male Urethra
___, from endoderm-lined urogenital sinus, does not empty to outside until an invagination of ectoderm covering glans of penis meets it and unites two tubes
Spongy (penile) urethra
Development of the Male Urethra
Spongy (penile) urethra, from ____, does not empty to outside until an invagination of ectoderm covering glans of penis meets it and unites two tubes
endoderm-lined urogenital sinus
Development of the Male Urethra
At same time ectoderm around periphery of glans burrows inward creating ____ and separating it from head of penis
prepuce (foreskin)
Development of the Male Urethra
At same time ectoderm around ____ burrows inward creating prepuce (foreskin) and separating it from head of penis
periphery of glans
Descent of the gonads
- gubernaculum testis
- proper ligament of the ovary + round ligament of the uterus
What are the 2 phases of descent of the testis?
- transabdominal phase
- inguinoscrotal phase
What happen during transabdominal phase of Descent of the testis?
- transabdominal phase: from the 7th embryonic week to the 3rd fetal month – the testes descend to the deep inguinal ring (regulated by the AMH) and stay there until the 7th fetal month
What happen during inguinoscrotal phase of descent of testes?
- transabdominal phase: from the 7th embryonic week to the 3rd fetal month – the testes descend to the deep inguinal ring (regulated by the AMH) and stay there until the 7th fetal month
The formation of female external genitalia is regulated by estrogens and the lack of ___ (have in male but not female)
dihydrotestosterone.
External genitalia – sexual dimorphism
- genital tubercle will become ___
- genital folds will become __
- glans penis ; glans clitoridis ♀
- corpus spongiosum and corpora cavernosa penis ♂ ; corpora cavernosa clitoridis and vestibular bulbs ♀
