Embryology 
/organogenesis/ 
Week 4: 06. 04 – 10. 04. 2009 
Development and teratology of reproductive 
system. 
Repetition: blood and hematopoiesis.
19. Indifferent stage in development of 
reproductive system. 
20. Development of male and female gonad. 
21. An overview of development of male 
and female genital duct. 
22. Development of external genital organs. 
23. Developmental malformations of 
urogenital system.
Male or female sex is determined by spermatozoon Y 
in the moment of fertilization
SRY gene, on the short arm of the Y chromosome, 
initiates male sexual differentiation. 
• The SRY influences the undifferentiated gonad to form 
testes, which produce the hormones supporting 
development of male reproductive organs. 
• Developed testes produce testosterone (T) and anti- 
Mullerian hormone (AMH). 
• Testosterone stimulates the Wolffian ducts development 
(epididymis and deferent ducts). 
• AMH suppresses the Mullerian ducts development 
(fallopian tubes, uterus, and upper vagina).
• Indifferent stage – until the 7th week 
• Different stage 
• Development of gonads 
• Development of reproductive passages 
• Development of external genitalia
Development of gonads 
mesonephric ridge (laterally) 
Dorsal wall of body: urogenital ridge 
genital ridge (medially), consisting of 
mesenchyme and coelomic 
epithelium 
(Wolffian 
duct) gonad
Three sources of gonad development: 
1 – condensed mesenchyme of gonadal ridges (plica genitalis) 
2 – coelomic epithelium (mesodermal origin) 
3 – gonocytes (primordial cells) 
gonocytes
Primordial germ cells – gonocytes – appeare among endoderm in dorsal wall 
of yolk sac. Gonocyte migrate along dorsal mesentery of hindgut into the 
gonadal ridges and induce (!) gonad development.
Indifferent gonad development 
• Gonocytes penetrate coelomic epithelium 
and mesenchyme 
Together with gonocytes, also cells of 
coelomic epithelium penetrate mesenchyma: 
primary (primitive) sex cords 
of indifferent gonad
TESTIS 
OVARY 
INDIFFERENT 
GONAD 
primary sex cords 
= medullary cords 
secondary sex cords ONLY 
= cortical cords in ovary 
Primary proliferation 
Secondary proliferation 
♂ 
♀ 
Tunica 
albuginea
TESTIS: 
Primary sex cords  tubuli semuniferi 
contorti 
Gonocytes  spermatogonia 
Coelomic cells  Sertoli cells 
Mesenchyme  Leydig cells, interstitial 
connective tissue 
OVARY: 
Primary sex cords  degenerate in ovarian medulla 
Secondary sex cords  disintegrate into the 
follicles: 
Gonocytes  oogonia 
Coelomic cells  follicular cells 
Mesenchyme  ovarian stroma 
♂ 
♀ 
Tunica albuginea
Development of reproductive passages 
(indifferent – differentiated stage) 
• Plica urogenitalis (urogenital ridge) – 2 ducts: 
Ductus mesonephricus (Wolffi) 
Ductus paramesonephricus (Mülleri)
Indifferent stage: 
Wolffian duct ♂ 
Müllerian duct ♀
Differentiated stage of development: 
Müllerian duct: 
Oviduct 
Uterus 
Cranial part of 
vagina 
Wolffian duct: 
Ductus epididymidis 
Ductus deferens 
Ductus ejaculatorius 
Ductuli efferentes in 
epididymis and rete 
testis originate from 
mesonephric tubules 
(see mesonephros)
EPOOPHORON 
PAROOPHORON 
GARTNER‘S 
DUCT 
+ RUDIMENTARY STRUCTURES 
APPENDIX 
EPIDIDYMIDIS
Development of external genatalia 
(indifferent – differentiated stage) 
Genital tubercle 
[tuberculum genitale] 
Urethral (cloacal) folds 
[plicae genitales] 
Labio-scrotal swellings 
[tori genitales]
Accessory glands development 
Seminal vesicles – develop as diverticles of 
ductus deferens (from Wolffian duct) 
Prostate – develops as numerous diverticles 
off urethra (from pelvic part of sinus urogenitalis)
Position of gonads during development 
• Gonad develops in only short, lumbal part of 
genital (gonadal) ridge (Th6 – S2) 
• Cranial part - disappeares 
• Caudal part transforms into gubernaculum 
• Testes – descensus into the scrotum 
• Ovaries – change also their position due to 
fusion of Müllerian ducts and formation of 
broad ligament
Testis – descens into the scrotum
Ovaries – change their position due to fusion of Müllerian 
ducts and formation of broad ligament
Congenital malformations - 1 
• Genetic anomalies: 
• Gonad(s) agenesis 
• Hermafroditism (ovotestes, ovary+testis) 
+ chromosomal aberations (45X/46XX, 
45X/46XY, 47XXY/46X, etc.) 
• Pseudohermafroditism – karyotype and 
gonads do not correspond to external 
genitalia 
• Gonadal hypolasia – Turner sy. (45X0), 
Klinefelter sy. (47XXY)
Congenital malformations - 2 
• Kryptorchism 
• Hydrocele testis 
• Hypospadias, epispadias 
• __________________________________ 
• Developmental defect of uterus (and vagina) 
uterus et vagina separatus, uterus bicornis, uterus septus or 
subseptus, uterus unicornis etc.
Repetition of blood 
• Composition of the blood 
• Hematocrit 
• Hemoglobin 
• Erythrocytes – shape, size, density per 1 ml 
• Reticulocytes 
• Anisocytosis 
• Poikilocytosis 
• Polycythemia (= polyglobulia)
• Granulocytes 
• Agranulocytes 
• Number of leukocytes per 1ml 
• Anemia 
• Leukocytopenia 
• Thrombocyte 
• Number of thrombocytes per 1ml 
• Hyalomere, granulomere
• Bone marrow structure 
• Erythropoiesis 
• Granulocytopoiesis 
• Megakaryocyte 
• Endomitosis 
• Differential white cell count (DWCC) !!! 
• Shift to the left or to the right
Neutrophilic granulocytes: 10-12 mm in Æ 
„band“ 
4 % in DWCC 
„segment“ 
67 % in DWCC
Basophilic granulocyte: 8 mm in Æ, only 1 % in DWCC
Eosinophilic granulocyte: up to 14 mm in Æ, 3 % in DWCC
Lymfocyte 
Monocyte 
5 % in DWCC 
20 % in DWCC
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  • 1.
    Embryology /organogenesis/ Week4: 06. 04 – 10. 04. 2009 Development and teratology of reproductive system. Repetition: blood and hematopoiesis.
  • 2.
    19. Indifferent stagein development of reproductive system. 20. Development of male and female gonad. 21. An overview of development of male and female genital duct. 22. Development of external genital organs. 23. Developmental malformations of urogenital system.
  • 3.
    Male or femalesex is determined by spermatozoon Y in the moment of fertilization
  • 4.
    SRY gene, onthe short arm of the Y chromosome, initiates male sexual differentiation. • The SRY influences the undifferentiated gonad to form testes, which produce the hormones supporting development of male reproductive organs. • Developed testes produce testosterone (T) and anti- Mullerian hormone (AMH). • Testosterone stimulates the Wolffian ducts development (epididymis and deferent ducts). • AMH suppresses the Mullerian ducts development (fallopian tubes, uterus, and upper vagina).
  • 5.
    • Indifferent stage– until the 7th week • Different stage • Development of gonads • Development of reproductive passages • Development of external genitalia
  • 6.
    Development of gonads mesonephric ridge (laterally) Dorsal wall of body: urogenital ridge genital ridge (medially), consisting of mesenchyme and coelomic epithelium (Wolffian duct) gonad
  • 7.
    Three sources ofgonad development: 1 – condensed mesenchyme of gonadal ridges (plica genitalis) 2 – coelomic epithelium (mesodermal origin) 3 – gonocytes (primordial cells) gonocytes
  • 8.
    Primordial germ cells– gonocytes – appeare among endoderm in dorsal wall of yolk sac. Gonocyte migrate along dorsal mesentery of hindgut into the gonadal ridges and induce (!) gonad development.
  • 9.
    Indifferent gonad development • Gonocytes penetrate coelomic epithelium and mesenchyme Together with gonocytes, also cells of coelomic epithelium penetrate mesenchyma: primary (primitive) sex cords of indifferent gonad
  • 10.
    TESTIS OVARY INDIFFERENT GONAD primary sex cords = medullary cords secondary sex cords ONLY = cortical cords in ovary Primary proliferation Secondary proliferation ♂ ♀ Tunica albuginea
  • 11.
    TESTIS: Primary sexcords  tubuli semuniferi contorti Gonocytes  spermatogonia Coelomic cells  Sertoli cells Mesenchyme  Leydig cells, interstitial connective tissue OVARY: Primary sex cords  degenerate in ovarian medulla Secondary sex cords  disintegrate into the follicles: Gonocytes  oogonia Coelomic cells  follicular cells Mesenchyme  ovarian stroma ♂ ♀ Tunica albuginea
  • 13.
    Development of reproductivepassages (indifferent – differentiated stage) • Plica urogenitalis (urogenital ridge) – 2 ducts: Ductus mesonephricus (Wolffi) Ductus paramesonephricus (Mülleri)
  • 15.
    Indifferent stage: Wolffianduct ♂ Müllerian duct ♀
  • 16.
    Differentiated stage ofdevelopment: Müllerian duct: Oviduct Uterus Cranial part of vagina Wolffian duct: Ductus epididymidis Ductus deferens Ductus ejaculatorius Ductuli efferentes in epididymis and rete testis originate from mesonephric tubules (see mesonephros)
  • 17.
    EPOOPHORON PAROOPHORON GARTNER‘S DUCT + RUDIMENTARY STRUCTURES APPENDIX EPIDIDYMIDIS
  • 21.
    Development of externalgenatalia (indifferent – differentiated stage) Genital tubercle [tuberculum genitale] Urethral (cloacal) folds [plicae genitales] Labio-scrotal swellings [tori genitales]
  • 25.
    Accessory glands development Seminal vesicles – develop as diverticles of ductus deferens (from Wolffian duct) Prostate – develops as numerous diverticles off urethra (from pelvic part of sinus urogenitalis)
  • 26.
    Position of gonadsduring development • Gonad develops in only short, lumbal part of genital (gonadal) ridge (Th6 – S2) • Cranial part - disappeares • Caudal part transforms into gubernaculum • Testes – descensus into the scrotum • Ovaries – change also their position due to fusion of Müllerian ducts and formation of broad ligament
  • 27.
    Testis – descensinto the scrotum
  • 29.
    Ovaries – changetheir position due to fusion of Müllerian ducts and formation of broad ligament
  • 30.
    Congenital malformations -1 • Genetic anomalies: • Gonad(s) agenesis • Hermafroditism (ovotestes, ovary+testis) + chromosomal aberations (45X/46XX, 45X/46XY, 47XXY/46X, etc.) • Pseudohermafroditism – karyotype and gonads do not correspond to external genitalia • Gonadal hypolasia – Turner sy. (45X0), Klinefelter sy. (47XXY)
  • 31.
    Congenital malformations -2 • Kryptorchism • Hydrocele testis • Hypospadias, epispadias • __________________________________ • Developmental defect of uterus (and vagina) uterus et vagina separatus, uterus bicornis, uterus septus or subseptus, uterus unicornis etc.
  • 40.
    Repetition of blood • Composition of the blood • Hematocrit • Hemoglobin • Erythrocytes – shape, size, density per 1 ml • Reticulocytes • Anisocytosis • Poikilocytosis • Polycythemia (= polyglobulia)
  • 41.
    • Granulocytes •Agranulocytes • Number of leukocytes per 1ml • Anemia • Leukocytopenia • Thrombocyte • Number of thrombocytes per 1ml • Hyalomere, granulomere
  • 42.
    • Bone marrowstructure • Erythropoiesis • Granulocytopoiesis • Megakaryocyte • Endomitosis • Differential white cell count (DWCC) !!! • Shift to the left or to the right
  • 43.
    Neutrophilic granulocytes: 10-12mm in Æ „band“ 4 % in DWCC „segment“ 67 % in DWCC
  • 44.
    Basophilic granulocyte: 8mm in Æ, only 1 % in DWCC
  • 45.
    Eosinophilic granulocyte: upto 14 mm in Æ, 3 % in DWCC
  • 46.
    Lymfocyte Monocyte 5% in DWCC 20 % in DWCC