1. 3th Week-Gastrulation Primitive Node and Streak (16 DAY)
Ectoderm
Mesoderm
Endoderm
Prochordal plate,Notochord,Primitive Node
Neuroctoderm

2. EMBRYONIC PERIOD ORGANOGENESIS
SOHRABI
17/آوريل/23

4. Neurolation,Ectoderm Central Nervous System Peripheral Nervous System
Neuroepithelium(Eyes.Ears,Nose)
Epidermis,Hair,Nail
Glands(Mammary G.Sweat G.Hypophysis)
Enamel
Derivities of NCC

5. Neurolation,Ectodermm
Derivities of NCC:
Ganglions(Cranial,Spinal,Autonome)
Medula of Adrenal G.
Melanocytes
Odontoblasts
Smooth muscles in vessels of face and forebrain
Meninges of forebrain
Glial cells,Schwan cells
C cells of thyroid G.
Connective tissue(Dermis) of face and neck
Heart(trunco conus cuhsion)

6. Neurulation
4/23/2017

9. The Events of Neurulation
Neural ectoderm thickens
Neural folds form producing Neural Groove
Neural folds contact
Cells rearrange forming Neural Tube with overlying Ectoderm
While the neural tube is forming, other embryonic tissues are undergoing changes too as the embryo itself is elongating. The following gives an idea of some of these changes and, more importantly, sets the stage for some of the developmental processes (e.g., limb formation) that we will cover in future lectures. . Note that as the neural tube is forming, many other events are occuring as well. The somites are forming and the embryo is elongating and flexing.

10. Cell Lineages At Neurula Stage
In the previous lecture on gastrulation, the role of the node (Hensen's Node) in organizing the overall body plan was discussed briefly. Historically, this special region of tissue has been shown to establish the vertebrate body plan in everything from frogs to zebra fish to mice (Nieto, Cell 98: ).  Experimentally this organizing ability is shown by the ability of transplanted nodal tissue to induce a second embryonic axis as revealed in the next diagram.

16. Hensen’s Node Induces Neural Axis
this special region of tissue has been shown to establish the vertebrate body plan in everything from frogs to zebra fish to mice
the node is an embryonic organizer in mammals
the mammalian node is not a classic organizer because it can't act alone to induce the embryonic axis but requires other anterior germ tissues to be fully effective
Thus progressive cellular interactions are more important rather than a single inductive event
In the previous lecture on gastrulation, the role of the node (Hensen's Node) in organizing the overall body plan was discussed briefly. Historically, this special region of tissue has been shown to establish the vertebrate body plan in everything from frogs to zebra fish to mice (Nieto, Cell 98: ).  Experimentally this organizing ability is shown by the ability of transplanted nodal tissue to induce a second embryonic axis as revealed in the next diagram.

18. 3th,4thWeek-Neurolation
Neural Folds(20 DAY)
Neural Groove(20 DAY)
Neural Crest,BMP4
Neural Tube(27 day)
Cranial and Caudal Neuropores(25 day,27 day)
Brain Vesicles,Spinal Cord
Otic Placodes(28 day)
Otic Vesicles
Lens Placodes

19. 3th Week-Neurolation Neural Plate(19 DAY)
Neuroctoderm(Forebrain,Midbrain), FGF Chordin,Noggin,Folistatin BMP4
Neuroctoderm(Hindbrain), FGF,WNT-3a
Ectoderm,Epiderm,BMP4
Ventral Mesoderm(Intermediate and Latral),BMP4
Dorsal Mesoderm(Paraxial),Chordin,Noggin ,Folistatin

23. 4th week,Mesoderm Paraxial Mesoderm(17 DAY) Latral Plate: (19 DAY)
Intermediate M.(20 DAY)
Latral M. : (21 DAY)
Somatic or Parietal M.
Splanchnic or Visceral M.

29. 4th week,Intermediate M. Latral M.
Nephrotome
Nephrogenic Cord
Urogenital System(kidneys,gonads, urinary bladder)+Spleen,Cortex of Adrenal G.
Somatic M. +Ectoderm Latral and Ventral Wall
Splanchnic M. + Endoderm Digestive tube

36. 4th ,5th week,Paraxial M.
WNT,Notch Cyclic genes Forming Gens(FGF8-, RA+)
Somitomers
Somites: (20 DAY to 35 DAY)
4 ,postcranial
8,neck
12 thoracic
5,lumbar
5,sacral
8-10,coxygeal

37. 4th week,Paraxial M. Somite:Cartilage,Bone,Muscle,C. T. of Derm
Sclerotome,Noggin,SHH PAX1
Myotome,WNT PAX3
MYF5
WNT+BMP4,FGF MYOD
Dermatome,WNT PAX3
NT-3

41. 3th Week Blood & Blood Vessels
VEGF
Splanchnic M.(Yolk Sac)+ Intermediate M.(AGM)(Liver,Bone Marrow)
(HOXB FLK1)
Hemangioblasts, Blood Islets:
Hematopoietic Stem Cells(Blood)
Angioblasts, VEGF(Endothelium)
Vasculogenesis, VEGF,PDGF,TGFb
Angiogenesis, VEGF
Arteris,Veins, Lymphatics

42. 3th Week Blood & Blood Vessels
Arteris,Veins, Lymphatics:
Notochord,SHH VEGF(Notch) Ephrin b2(EPH) Artery,Vein
Notochord,SHH VEGF(Notch) Eephrin b4(EPH) Vein
PROX Lymphatics

43. Capillary Hemangioma
Infants
10%
Focal.Diffuse
IGF2
VEGF?

46. 3th Week Blood & Blood Vessels
VEGF
Splanchnic M.(Yolk Sac)+ Intermediate M.(AGM)(Liver,Bone Marrow)
(HOXB FLK1)
Hemangioblasts, Blood Islets:
Hematopoietic Stem Cells(Blood)
Angioblasts, VEGF(Endothelium)
Vasculogenesis, VEGF,PDGF,TGFb
Angiogenesis, VEGF
Arteris,Veins, Lymphatics

47. 3th Week Blood & Blood Vessels
Arteris,Veins, Lymphatics:
Notochord,SHH VEGF(Notch) Ephrin b2(EPH) Artery,Vein
Notochord,SHH VEGF(Notch) Eephrin b4(EPH) Vein
PROX Lymphatics

48. Capillary Hemangioma
Infants
10%
Focal.Diffuse
IGF2
VEGF?

53. As the neural tube is forming, the somites are forming
Embryo consists of all primary germ layers
Development continues to form tissues & organs
As the neural tube is forming,
the somites are forming
& the embryo is elongating & flexing

54. 4th Week, Endoderm Brain Vesicle growth
Craniocaudal Folding (Cranial folding, Caudal Folding)
Foregut
Hindgut
Midgut+Vitelline duct
Buccopharyngeal rupture(4th week)
Cloacal rupture(7th week)

55. 4th Week, Endoderm Somites formation Latral Folding
Latral and Ventral Wall
Vitelline Duct(2nd Month in chorion cavity,3rd Month,Close)
Cloaca

56. 4th Week, Endoderm Endoderm Epithelium: Primary gut Vitteline duct
Allantois
Auditory duct,Tympanic cavity,Respiratory duct, urinary bladder,urethra,Thyroid,Parathyroid,Liver and Pancreas paranchyma,Thymus and Tonsils stroma

62. Folding of the germinal disk (4th week)

65. Stage 7
Approx. 19th day: Dorsal view
0.4 mm
Characteristic signs: Mesoblast immigration Notochordal process Neural plate Genesis of the blood vessel system and formation of blood

66. Stage 8
Approx. 23th day mm
Characteristic signs: Pear shaped embryo Axial process Neurenteric canal

67. Characteristic signs: Embryo with somites (1-3 somites) Pharyngeal membrane Neural groove Caudal eminence Intraembryonic coelom Cardiac primordium, septum transversum Placode and auditory pit
Stage 9
Approx. 25th day mm

68. 2 - 3.5 mm Approx. 28th day Stage 10a, 10b
Characteristic signs: Lateral folding Closure of the neural groove into a neural tube The 2 first pharyngeal arches appear Ophthalmic vesicle Rupture of the pharyngeal membrane somites
Stage 10a, 10b
Approx. 28th day mm

69. Characteristic signs: Closure of the rostral neuropore Nasal placode Ophthalmic vesicle Auditory pit 13 – 20 somites
Stage 11
Approx. 29th day mm

70. Stage 12
Approx. 30th day
3 - 5 mm
Characteristic signs: Closure of the caudal neuropore Third pharyngeal arch Buds of the upper extremities Cervical sinus 21–29 somites

71. Characteristic signs: Buds of the lower extremities Lens placode Auditory pit Fourth pharyngeal arch More than 30 somites
Stage 13
Approx. 32th day
4 - 6 mm

72. Characteristic signs: Opthalmic vesicle Genesis of the endolymphatic canal Augmented cephalo-cervical flexure Cerebellar primordium Visible ocular primordium Sixth pharyngeal arch
Stage 14
Approx. 33th day
5 - 7 mm

73. Stage 15
Approx. 36th day
7 - 9 mm
Characteristic signs: Lens vesicle covered with the ectoderm Auditory primordium Genesis of the hand plate

74. Characteristic signs: Deep, ventrally lying nasal pit Pigmentation of the eye Genesis of the foot plate Physiologic umbilical hernia
Stage 16
Approx. 39th day mm

75. Stage 17
Approx. 41rst day mm
Characteristic signs: External acoustic meatus The circumference of the head increases The trunk lengthens Fusion of the 6 auricular hillocks Atrophy of the embryonic tail Formation of the interdigital zones

76. Characteristic signs: Toe primordium Nasal primordium The elbow joint forms Gonadal gender can be determined in male embryos
Stage 18
Approx. 44th day mm

77. Characteristic signs: Lengthening and straightening of the torso Appearance of the external acoustic meatus Genesis of the hip and knee joints Atrophied embryonic tail Rupture of the cloacal membrane
Stage 19
Approx. 46th day mm

78. Characteristic signs: Arms in pronation Separated fingers Gonadal gender determinable in female embryos
Stage 20
Approx. 49th day mm

79. Stage 21
Approx. 51rst day mm
Characteristic signs: Subcutaneous vessel network of the head spreads out Hands and feet come closer and touch each other

80. Characteristic signs: Development of the eyelids and the external ear canal Tragus and antitragus Nasal septum
Stage 22
Approx. 53rd day mm

81. Characteristic signs: Angle between the head and trunk amounts to 30° The head makes 50% of the embryo's size The head is rounded, the extremities lengthened and stand out from the body Chin Nasal pit Development of the external genital primordium
Stage 23
Approx. 56th day mm

84. THE END