L20 – Development of the Male and Female Reproductive System

Question 1

Tract the structures from Testis to Penis?

Answer 1

Testis > Epididymis > Ductus Vas Deferens > Ejaculatory duct > accessory sec glands > urethra > penis

Question 2

List the accessory sex glands in male and function?

Answer 2

Prostate, seminal vesicles, bulbourethral gland

Production of secretions (semen)

Question 3

Function of epididymis?

Answer 3

Reservoir for sperm (sperm maturation)

Question 4

List the structures from ovary to labia majora?

Answer 4

Ovary > uterine tube > uterus > vagina + greater and lesser vestibular glands > Labia majora and minora + clitoris

Question 5

Summarize the differentiation of germ layers in the Indifferent stage of gonad development?

Answer 5

Endoderm:
Primordial germ cells migrate from yolk sac

Mesoderm:
Gonadal ridge (part of urogenital ridge) forms from intermediate mesdoerm, contains:
a) Mesenchymal tissue
b) epithelial tissue: gonadal cords and mesodermal epithelium

Question 6

Summarize the testis** structures formed from bipotential/ indifferent stage of gonad development?

Answer 6

Primordial germ cells (endoderm)&raquo_space; spermatogonia

Gonadal ridge (mesoderm)&raquo_space;Seminiferous cords and interstitial cells

Mesodermal epithelium&raquo_space; Mesothelium

Question 7

Summarize the ovary** structures formed from bipotential/ indifferent stage of gonad development?

Answer 7

Primordial germ cells&raquo_space; oogonia

Gonadal ridge&raquo_space; Primordial follicles and intersitital cells

Mesodermal epithelium&raquo_space; mesothelium

Question 8

Summarize the mature structures in testis formed from differentiated gonads?

Answer 8

Spermatogonia&raquo_space; spermatozoa

Seminiferous cords and intersitital cells&raquo_space; Tunea albuginea, Interlobular septa, Mediastinum testis, Sertoli and Leydig cells

Mesothelium&raquo_space; visceral layer of tunica vaginalis

Question 9

Summarize the mature structures in ovaries formed from differentiated gonads?

Answer 9

Oogonia&raquo_space; ovum

Primordial follicles&raquo_space; granulosa and theca cells

Interstitial cells&raquo_space; tunica albuginea and other interstitial cells

Mesothelium&raquo_space; germinal epithelium

Question 10

Describe the formation of upper and lower genital ducts during indifferent stage?

Answer 10

Upper:
Nephrogenic cord from intermediate mesoderm (part of genital ridge)&raquo_space; Mesonephric and paramesonephric ducts

Lower:
Cloaca from endoderm&raquo_space; urogenital sinus

Question 11

Describe the differentiation of male genital ducts from indifferent stage?

Answer 11

Mesonephric ducts transform

Paramesonephric ducts degenerate

Urogenital sinus&raquo_space; distal urethra

Question 12

Describe the differentiation of female genital ducts from indifferent stage?

Answer 12

Paramesonephric ducts transform

Mesonephric ducts degenerate

Urogenital sinus&raquo_space; Uterovaginal primordium

Question 13

Describe the structures derived from the differentiated stage of genital duct development in male?

Answer 13

Mesonephric duct derive into:
• efferent ductules 
• duct of the epididymis 
• vas deferens 
• ejaculatory duct 
• Seminal glands 

Distal urethra derive into :
• Penile urethra
• Prostate
• Bulbourethral glands

Question 14

Describe the structures derived from the differentiated stage of genital duct development in female?

Answer 14

Paramesonephric duct derives:

• Uterine tubes
• Uterus
• Upper Vagina

Uterovaginal primordium derives:

• Greater vestibular glands
• Lower Vagina with hymen

Question 15

Summarize the formation of external genitalia in male?

Answer 15

Genital tubercule&raquo_space; Primordial phallus (long)&raquo_space; Glans penis and shaft of penis

Urogenital folds fuse on ventral penis&raquo_space; penile urethra

Labioscrotal swellings fuse&raquo_space; scrotum

Question 16

Summarize the formation of external genitalia in female?

Answer 16

Genital tubercule&raquo_space; Primordial phallus (short)&raquo_space; Clitoris

Urogenital folds don’t fuse&raquo_space; Vestibule and labia minora

Labioscrotal swelling&raquo_space; labial folds&raquo_space; Labia majora

Question 17

Describe the changes to the gonadal ridge and migration of primordial germ cells?

Answer 17

Gondal ridge= bulge medial to mesonephros at post. abdominal wall:
Epithelial lining invaginate into mesenchyme, forms gonadal cords

Primordial germ cells: Migrate from exit of allantois&raquo_space; gut tube&raquo_space; dorsal mesentery of hindgut&raquo_space; gonadal ridge&raquo_space; infiltrate gonadal cords

Question 18

List the primordial cells in the indifferent gonad?

Answer 18

Mesothelium, gonadal cords, mesenchyme = mesoderm origin

Primordial germ cells = endoderm origin

Question 19

Describe the formation of testis from indifferent gonad? (5)

Answer 19

1) Gonadal cords infiltrated with primordial germ cells&raquo_space; elongate/ enlarge into seminiferous cords

2) Distal gonadal cord (no germ cell) forms straight tubules
» Rete testis: connect seminiferous cords with efferent ductules/mesonephric tubules&raquo_space; connect with Mesonephric duct (Wolffian duct)

3) Mesenchymal cells&raquo_space; Myoepithelial cells, Leydig, interstitial cells
4) Epithelial cells of gonadal cord = Sertoli cells
5) Mesothelium&raquo_space; tunica vaginalis, Tunica albuginea, Septa

Question 20

Describe the formation of ovary from indifferent gonad? (5)

Answer 20

1) Gonadal cords infiltrated with primordial germ cells form follicles: oogonium + follicular cells (from gonadal cord epithelium)
2) Distal gonadal cords degenrate into Rete ovarii, no connection with mesonephros
3) Epithelium of gonadal ridge&raquo_space; tunica albuginea, germinal epithelium

Question 21

Compare the differentiation of mesonephric duct and paramesonephric duct in male and female?

Answer 21

Male:

• Testosterone from leydig cells transforms mesonephric duct
• Anti-Mullerian hormone from Sertoli cells degenerates Paramesonephric ducts

Female:

• No testosterone = Mesonephric duct degeneration
• No anti-Mullerian hormone = paramesonephric duct transform

Question 22

What structure separates cloaca into 2 canals?

Answer 22

Urorectal septum splits cloaca into

• Urogenital sinus (anterior)
• Rectum (posterior)

Question 23

List the structures transformed from mesonephric duct in male?

Answer 23

Testosterone: 
convert mesonephric duct into
-epididymis, 
-Ductus (vas) Deferens 
-seminal vesicle

Question 24

List the structures transformed from paramesonephric duct in female?

Answer 24

Lack of Anti-Mullerian hormone:
Paramesonephric duct form:

• Fallopian tube
• Uterus and Upper vagina (fused paramesonephric duct)

Question 25

List the sex organ structures derived from urogenital sinus in male?

Answer 25

Prostate gland (development controlled by dihydrotestosterone (DHT)) Bulbourethral glands Penile urethra

Question 26

List the sex organ structures derived from urogenital sinus in female?

Answer 26

 Urethral and paraurethral glands  Greater vestibular glands (of Bartholin) Lower vagina + hymen

Question 27

Describe the development of uterus and vagina?

Answer 27

1) Paramesonephric ducts fuse + Uterine septum degenerate >> uterine tube 2) Sinus tubercule (from urogenital sinus) enlarge into sinovaginal bulbs >> fuse with uterine tube 3) Sinovaginal bulbs lumen degenerate >> become patent with space >> forms middle and lower vagina + hymen

Question 28

List 3 developmental anomalies of uterus?

Answer 28

- Double uterus: failure of paramesonephric ducts to fuse - Uterus divided into 2: failure of uterine septum to degenerate - Dysmorphic/ absent half of uterus: failure on one paramesonephric duct to differentiate

Question 29

Embryonic origin of phallus?

Answer 29

Genital tubercle: Produced by proliferating mesenchyme at the cranial end of cloacal membrane

Question 30

Describe the formation of precursors of external genitalia?

Answer 30

Superior to cloacal membrane = genital tubercule Lateral to cloacal membrane = 2 urogenital folds More lateral: 2 Labioscrotal swellings

Question 31

Which week of development sees distinguishing sexual characteristics?

Answer 31

9th week External genitalia are not fully differentiated until the 12th week.

Question 32

Describe the formation of external male genitalia?

Answer 32

1) Genital tubercule rapidly elongates into primordial phallus >> glans and shaft of penis 2) Urogenital folds pulled along with genital tubercule >> fuse at underside of penis (perineal raphe) 3) Labioscrotal swelling = forms exterior wall and scrotum 4) Surface ectoderm invaginates > ectodermal cord > fuse with spongy urethra + create Navicular fossa and prepuce

Question 33

Embryonic defect causing hypospadia?

Answer 33

ectopic location of the urethral meatus Incomplete fusion of the urethral groove: - incomplete development of the prepuce - ventral skin deficiency/penile curvature

Question 34

Describe the formation of external genitalia in female?

Answer 34

1) Genital tubercule curves ventrally > clitoris 2) Urogenital folds do not fuse > labia minora 3) Labioscrotal fold do not fuse >> Labia majora

Question 35

Describe the relocation of the testis during development?

Answer 35

End of 2nd month: - Gonads and mesonephros anchored to posterior abdominal wall - Gubernaculum (fibromuscular cord) connect gonads to labioscrotal swelling - Upper inguinal canal degenerates - Testis dragged down/ out of abdominal cavity into scrotum below inguinal canal, behind Vaginal process 7 month: - Upper vaginal process fuse, close off scrotum from Abd. cavity

Question 36

Embryonic defect in ectopic testis or Cryptochidism?

Answer 36

Cyptochidism = retention of testis in abdominal cavity Failure of correct migration into scrotum

Question 37

Embyronic defect causing Hydrocele formation in testes?

Answer 37

Hydrocele = fluid secreting cyst between parietal and visceral layer of tunica vaginalis Failure of vaginal process to fuse properly >> congenital indirect inguinal herniation (intestine loop pushed into scrotum)

Question 38

Describe the relocation of the ovaries during development?

Answer 38

7th week: - Gubernaculum attached to ovary, no shortening due to lack of Testosterone - Gubernaculum persists as ligament: i) cranial part - round ligament of OVARY, connect ovary to uterus ii) Caudal part - round ligament of UTERUS, connect uterus to labia majora