6.2 Embryonic development of EXTERNAL GENITALIA and GENITAL DUCT DERIVATIVES

Question 1

MESONEPHRIC DUCTS aka

Answer 1

WOLFIAN DUCTS

Question 2

PARAMESONEPHRIC DUCTS aka

Answer 2

MULLARIAN DUCTS

Question 3

when does DEVELOPMENT of EXTERNAL GENITALIA start

Answer 3

around 4 WEEKS

Question 4

DEVELOPMENT OF EXTERNAL GENITALIA landmark weeks

Answer 4

week 4
(week 7)
week 9
week 12

Question 5

DEVELOPMENT OF EXTERNAL GENITALIA
what happens at WEEK 4:

Answer 5

proliferating MESENCHYME produces a GENITAL TUBERCLE - primordium of CLITORIS or PENIS

at CAUDIAL (TAIL) end

Question 6

DEVELOPMENT OF EXTERNAL GENITALIA
what do we have at week 7

Answer 6

External Genitalia are SEXUALLY UNDIFFERENTIATED

• only takes place when testosterone produced (8 weeks)

Question 7

DEVELOPMENT OF EXTERNAL GENITALIA
what begin to appear at WEEK 9

Answer 7

DISTINGUISHING SEXUAL CHARACTERISTICS

Question 8

DEVELOPMENT OF EXTERNAL GENITALIA
what do we have at WEEK 12 and what happens

Answer 8

FULLY DIFFERENTIATED external genitalia

Question 9

which GROWTH FACTOR is found to be involved in the SINGALLING PATHWAYS in the EARLY DEVELOPMENT of EXTERNAL GENITALIA (WEEK 12)

Answer 9

FGF8

(testosterone is not the only factor involved)

Question 10

DEVELOPMENT OF EXTERNAL GENITALIA

what develop on EACH SIDE of the CLOACAL MEMBRANE

Answer 10

LABIOSCROTAL SWELLINGS and UROGENITAL FOLDS

Question 11

DEVELOPMENT OF EXTERNAL GENITALIA

GENITAL TUBERCLE soon ELONGATES to form a …

Answer 11

PRIMORDIAL PHALLUS
- PENIS / CLITORIS

Question 12

DEVELOPMENT OF EXTERNAL GENITALIA

in a FEMALE fetus the URETHRA and VAGINA OPEN into a COMMON CAVITY called ..

Answer 12

the VESTIBULE of the VAGINA

Question 13

what is MASCULINIZATION INDUCED by

Answer 13

DHT
DIHYDROTESTOSTERONE

Question 14

what is DHT (DEHYDROTESTOSTERONE) PRODUCED peripherally by..

Answer 14

5 ALPHA-REDUCTASE CONVERSION of TESTOSTERONE (produced by Leydig cells)

Question 15

TESTOSTERONE is converted to DHT by which ENZYME in order for it to work

Answer 15

5 ALPHA REDUCTASE

Question 16

in MALES
the EPITHELIUM of the URETHRA comes from the..

Answer 16

ENDODERM of the UROGENITAL SINUS (comes from cloaca)

(except for that of the distal part of the spongy urethra in males)

Question 17

GLANULAR part of the URETHRA (urethra of the GLANS) is derived from..

Answer 17

ECTODERM

Question 18

the GENITAL TUBERCLE, CONNECTIVE TISSUE and SMOOTH MUSCLE are derived from..

Answer 18

SPLANCHNIC MESENCHYME

Question 19

the Embryo has 2 PAIRS of GENITAL DUCTS:

Answer 19

MESONEPHRIC DUCTS (WOLFFIAN) - persist in males

PARAMESONEPHRIC DUCTS (MULLERIAN) - persist in females

Question 20

example of a vestigial structure that remains after DUCTS regress
remnant of paramesonephric duct:

Answer 20

APPENDIX TESTIS in the MALE

Question 21

what happens to the MESONEPHRIC DUCTS in FEMALE embryos and why

Answer 21

REGRESS
in ABSENCE of TESTOSTERONE

Question 22

what happens to the PARAMESONEPHRIC DUCTS in FEMALE embryos and why

Answer 22

DEVELOP
due to ABSENCE of AMH (ANTIMULLERIAN HORMONE)

(form most of the female genital tract)

Question 23

female sexual development does not depend on the presence of ovaries or hormones until..

Answer 23

puberty

Question 24

what do both MESONEPHRIC DUCTS and PARAMESONEPHRIC DUCTS connect to

Answer 24

UROGENITAL SINUS (developed from cloacal membrane)

Question 25

FEMALES: CRANIAL PARTS of the PARAMESONEPHRIC DUCTS remain UNFUSED and become the..

Answer 25

UTERINE TUBES (fallopian tubes)

Question 26

FEMALES: CAUDAL PARTS of the PARAMESONEPHRIC DUCTS FUSE to form the..

Answer 26

UTEROVAGINAL PRIMORDIUM - uterus, upper 3rd of vagina and broad ligament

Question 27

FEMALES: which end of the PARAMESONEPHRIC DUCTS FUSE and what does it form

Answer 27

CAUDAL - UTEROVAGINAL PRIMORDIUM

Question 28

FEMALES what will the UTEROVAGINAL PRIMORDIUM become

Answer 28

Uterus, Upper 3rd of VAGINA, BROAD LIGAMENT

Question 29

FEMALES important GENE for regulating PARANEPHRIC DUCTS

Answer 29

HOX genes

Question 30

FEMALES the ENDOMETRIAL STROMA and MYOMETRIUM (connective tissue and muscle) are derived from..

Answer 30

SPLANCHNIC MESENCHYME

Question 31

EPITHELIUM of the VAGINA develops from the..

Answer 31

ENDODERM of the UROGENITAL SINUS

Question 32

FIBROMUSCULAR WALL of VAGINA develops from the..

Answer 32

UTEROVAGINAL PRIMORDIUM

Question 33

DEVELOPMENT OF VAGINA when UTEROVAGINAL PRIMORDIUM meets the UROGENITAL SINUS this area is called the..

Answer 33

SINUS TUBERCLE

Question 34

DEVELOPMENT OF VAGINA formation of SINUS TUBERCLE INDUCES the formation of..

Answer 34

SINOVAGINAL BULBS paired endodermal outgrowths which extend from the UROGENITAL SINUS to the CAUDAL END of the UTEROVAGINAL PRIMORDIUM

Question 35

DEVELOPMENT OF VAGINA SINOVAGINAL BULBS FUSE to form a..

Answer 35

VAGINAL PLATE

Question 36

DEVELOPMENT OF VAGINA how does the VAGINAL PLATE form the LUMEN of the VAGINA

Answer 36

CENTRAL WALLS of vaginal plate BREAK DOWN

Question 37

DEVELOPMENT OF VAGINA the PERIPHERAL CELLS of the VAGINAL PLATE form the

Answer 37

VAGINAL EPITHELIUM

Question 38

DEVELOPMENT OF VAGINA later in foetal life the LUMEN of the VAGINA is SEPARATED from the cavity of the UROGENITAL SINUS by a MEMBRANE: and how is it formed

Answer 38

HYMEN - formed by INVAGINATION of the POSTERIOR WALL of the UROGENTIAL SINUS (ruptures during Perinatal period - first 28 days after birth - and remains as a thin mucous membrane just within the vaginal orifice)

Question 38

DEVELOPMENT OF VAGINA later in foetal life the LUMEN of the VAGINA is SEPARATED from the cavity of the UROGENITAL SINUS by a MEMBRANE: and how is it formed

Answer 38

HYMEN - formed by INVAGINATION of the POSTERIOR WALL of the UROGENTIAL SINUS (ruptures during Perinatal period - first 28 days after birth - and remains as a thin mucous membrane just within the vaginal orifice)

Question 39

DEVELOPMENT OF MALE DUCTS when do TESTES start to produce TESTOSTERONE

Answer 39

WEEK 8-12

Question 40

DEVELOPMENT OF MALE DUCTS when do TESTES start to form AMH (paramesonephric ducts disappear by epithelial-mesenchymal transformation)

Answer 40

WEEK 6-7

Question 41

DEVELOPMENT OF MALE DUCTS as MESONEPHROS (kidney development) DEGENERATES, some tubules PERSIST as..

Answer 41

EFFERENT DUCTULES opening into the MESONEPHRIC DUCT

Question 42

DEVELOPMENT OF MALE DUCTS MESONEPHRIC DUCTS become

Answer 42

DUCT of EPIDIDYMIS or distal to epididymis, acquires a thick investment of SMOOTH MUSCLE and becomes the DUCTUS DEFERENS or EJACULATORY DUCT (from mesonephric duct between the duct of seminal vesicle and the urethra)

Question 43

DEVELOPMENT OF MALE DUCTS LATERAL OUTGROWTHS of the CAUDAL END of the MESONEPHRIC DUCT become..

Answer 43

SEMINAL VESICLES

Question 44

MALES SECRETIONS of SEMINAL VESICLES contribute how much of the volume of EJACULATE

Answer 44

50-80%

Question 45

MALES multiple ENDODERMAL OUTGROWTHS arise from the Prostatic part of the URETHRA and GROW INTO the SURROUNDING MESENCHYME to FORM..

Answer 45

PROSTATE GLAND

Question 46

what do the EFFERENT DUCTS of testes come from

Answer 46

MESONEPHRIC TUBULES

Question 47

What does RETE TESTES come from

Answer 47

Sex Cords

Question 48

what do the CLITORIS and PENIS originate from

Answer 48

GENITAL TUBERCLE (elongates into primordial phallus)