Devo Repro Flashcards
What three components necessary for devo repro system
gonads, ducts, external genitals
Sex determination occurs at _____
sex differntiaiton occurs at _____ from gentic and epigentic factors
Fertilization
embryonic period into fetal period
Presence and Action of ________________, appears to actively influence sexual differentiation in a male direction
Androgens
A second factor __________________________________________ is involved in promoting regression of the paramesonephric (müllerian) ducts !
Mullerian inhibiting substance
Intermediate mesoderm is responsible for which male repro organs
Epididymis, ductus deferens, ejact duct, seminal vesicle and testes
Intermedite mesoderm is responsible for which repro systems in female?
oviduct, Uterus, Part of Vagina, ovarys
Intermediate mesoderm–> UG ridge–> _______–> epididymis/ductus deferens/ejact duct/ seminal vesicle
Mesonephric duct
Mesonephric tubles form the _____ in male
efferent ductules
Paremesonephric duct forms what in female
oviduct, uterus, part of vagina
Part of vagina, prostate glands and ducts, penis, scrotum, labia, vestibule, clitoris all from:
Endoderm –> primitive UG sinus–> definitive UG sinus
During Development the Forming Reproductive Organs Pass Through a Unique Intermediate Phase Termed the
Indifferent Stage
What forms during Indifferent Stage
Progenitors of the gonads, reproductive ducts and external genitalia form, but are morphologically indistinct with respect to sex
The Indifferent Gonad Forms within the______of the Nephrogenic Cord
Ventromedial aspect
• The gonad primordium is a morphologically distinct part of the nephrogenic cord: With appearance of gonad primordium, the ridge is renamed the
UG Ridge
During indifferent stage, the coelomic epithelium covering the medial side of the nephrogenic cord_____ while the underlying mesenchyme_____
proliferates
condenses
What cell Types Found in Forming Gonads?
• germ cells • supporting cells • interstitial cells
Gamete progenitor cells of extragonadal origin that migrate to gonad
Primordial Germ Cells (PGC)
Persistence of PGC’s outside the gonad may generate a
teratoma
The Primitive Gonad Develops Cranial & Caudal Attachments
Cranial:
Caudal:
The UG ridge stays attached to body wall ______ via mesentary
crania: becomes suspensory ligament
caudally: gubernaculum
*stays attached DORSALLY
The
“The Wolffian System” Associated with the mesonephric kidney
Mesonephric Duct (MD)
“The Mullerian System”, Lateral to MD
• Invagination of coelomic epithelium
• Formation induced by MD
• Contacts the UG Sinus
Paramesonephric Duct
External Swellings in the Caudal Region of the Embryo are the Progenitors of the
External Genitalia
External Swellings in the Caudal Region of the Embryo = Progenitors of the External Genitalia
Genital Tubercle = A midline swelling
Urethral (Urogenital) Folds = Surround the UG membrane
Labioscrotal Swellings = Lateral to the Urethral (Urogenital) Folds
Summary of Development During the Indifferent Stage
During Weeks 4 – 6(7) a sexually determined but sexually undifferentiated embryo has formed:
Pair of undiff gonads
two sets of ducts: mesonephric and paramesonephric
elevations and folds round opening of UG sinus
Differentiation of the_____ Occurs First
This Suggested that some type of ”Switch” may be involved in sexual differentiation of the gonad!
Gonad
The SRY gene on the Y chromosome [the hypothesized “switch”] directs gonad differentiation in a male direction
Encodes for a DNA binding protein the
Testicular Determining Factor (TDF
Expression of the SRY Gene Results in the Formation of
Testes [week 6-7]
Germ Cells: PGC form ______
spermatogonia
- Express Sox 9
- Form from coelomic epithelial cords
• Associate w/germ cells (seminiferous cords)
Sertoli Cells (supporting cells)
(interstitial cells) Secrete testosterone [week 8]
Leydig Cells
A fibrous layer, the _______, forms a capsule around the testis!
tunica albuginea
In the Absence of SRY Gene Expression, the Indifferent Gonad Develops into an____
_____is expressed in coelomic epithelial cells
Ovary
WNT4
What happens to Germ cells in abscence of SRY?
What about follicular/granulosa cells?
Germ Cells: PGC become oogonia
Follicle/Granulosa Cells (supporting cells) Associate w/oogonia forming **primordial follicles **
Testes and Ovaries Undergo Positional Changes During Development: Testis Descend into the Scrotum [usually before birth]
Failure of descent =_______
Ovaries Descend into the Pelvis
Cryptorchidism
In the Presence of _________ (male embryo), the Growth and Differentiation of the Mesonephric Ducts are Supported
Testosterone
In the Male, there is a continuous duct system from
Seminiferous Tubules to the Urethra
In the Male, Androgens also Induce and Support Primordia of the
Male Accessory Sex Glands
The Prostate Gland may have a Dual Origin
- Both primordia begin as buds
- Most Glands - form from buds of the____ lining of the pelvic part of UG sinus
- Central Zone Glands – form from buds from the_____
most glands: endoderm
central: mesoderm
Budding of prostate gland is induced by
UG sinus Mesenchyme
Presence of ______ in Male Embryos Stimulates the Regression of the Paramesonephric Ducts
Mullerian inhibiting substance
Part of the prostatic utricle is derived from the
Paramesonephric Duct
In the Female Embryo, Absence of _____ Allows the Growth and Differentiation of the Paramesonephric Ducts
MIS
In the Absence of ________ (Female Embryo) the Development of the Mesonephric Ducts is Not Supported : atrophy
remanants can be seen in broad ligament
testosterone
- The_____ 1/3 Paramesonephric Fuses, and becomes the Uterus & part of the Vagina
- The____ 2/3 Paramesonephric remains unfused, and becomes the Oviduct
Caudal
Cranial
The Paramesonephric Ducts & pelvic part of UG Sinus interact with each other to form the
Vagina
Abnormal Development of the Paramesonephric Duct
Uterine anomalies are Common but may not be Clinically Significant
They Range from Total Absence to Complete Duplication of Uterus & Vagina
During the Indifferent Stage, the Interior of the Definitive UG Sinus is Remodeled
What do we get for females?
part of vaginal and vestibule from Interior of definitive UG sinus
During the Indifferent Stage, the Interior of the Definitive UG Sinus is Remodeled ; what male structures do we get?
Distal Prostatic & Membranous Urethra
Phallic Portion
Penile Urethra
In the Presence of __________, the Genital Tubercle and Urethral Folds Elongate
DHT
Presence of DHT and its effects on Genital tubercle and urethtral folds;
- Further elongation of phallus
- Cloacal membrane rupture and urethral plate formation
- Urethral Folds pulled forward forming a urethral groove lined with endoderm
- Urethral folds fuse ventrally during month 3
- The glans is from distal end of genital tubercle
- Perineal area elongates; labioscrotal folds fuse ventrally to form scrotum and eventually receive the testes
The Lining of the Penile Urethra is derived from the
The Portion of the Penile Urethra within the Glans is formed by an
Endoderm of the Phallic Part of the UG Sinus
Ingrowth of Ectoderm
Normal Development of the Male Reproductive Ducts and External Genitalia Depends on:
- Presence of __________________
- Conversion of testosterone to dihydrotestosterone by ____________ in the accessory glands and external genitalia
Androgens secreatd by testis
5-Alpha reductase
Abnormal Formation of the Male Urethra
Urethral opening proximal to tip of glans:
Urethra open dorsally:
Hypospadias
Epispadias
In the Absence of _________, the Primordia of the External Genitalia Develop in a Female Direction
DHT
No DHT get female external genitals
The Genital Tubercle forms the____
- The Urethral Folds form the _____
- The Labioscrotal Swellings form the ____
The Genital Tubercle forms the Clitoris
- The Urethral Folds form the Labia Minora
- The Labioscrotal Swellings form the Labia Majora
sex differentiation also occurs in the brain in centers controlling release of gonadotrophic hormones leading to____ release in females and pulsatile but _____release in males
cyclic (females)
non-cyclic (males)
Undifferentiated gonads, ducts and external genitalia form initially during the
indifferent stage [week 4 - 6].
• Expression of the SRY gene directs gonads to
form testes
Androgens produced by testes support development of ______; MIS inhibits the development of the _______; primordia of the external genitalia develop in a male direction. Mesonephric duct forms the male duct system (except urethra).
mesonephric duct
paramesonephric duct
Absence of SRY gene expression allows gonads to become.
ovaries
• Absence of androgens allows ______ to atrophy & allows external genitalia primordia to develop in a female direction (supported by estrogen); absence of____ allows paramesonephirc ducts to develop. Paramesonephric ducts form female duct system (except caudal vagina)
mesonephric duct
MIS
Gonad with andorgen =
Gonad no androgen =
testis–>secreate andodrgen
ovary–> no androgen
Meonephric duct in presence of adnrogen forms:
Efferent Ductules Epididymis
Vas Deferens & Seminal Vesicle
Paramesonephric duct in ABSENCE of MIF and Androgen: forms
Oviduct Uterus
Upper Vagina
external genitalial starts as: genital tubercle, urethral folds, labrioscrotal folds:
Prescence of Androgens DHT:
Penis, scrotum, prostate
external genitalial starts as: genital tubercle, urethral folds, labrioscrotal folds:
Absence of Androgens or DHT
form: clitoris, labia minus, majus and lower vagina
