histogenesis 151 course 5: cells and tissue development
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Histogenesis
151Course 5: Cells and tissue
development
Course 5: Development• 137 Case report: Thalidomide• 138 Basic morphogenetic processes• 139 Regeneration and reparation• 140 Female reproductive system• 142 Gametogenesis and fertilization• 144 Genetic determination of the sex• 145 Signalization in development• 146 Blastogenesis, notogenesis• 149 Notogenesis, neurulation• 150 Embryonic period• 151 Histogenesis• 152 Human reproductive genetics• 153 Developmental toxicology• 154 Ageing
• 141 Female reproductive system• 143 Male reproductive system• 147 Extraembryonic organs• 148 Early embryonic development, chick
Aim
• histogenesis – the origin and development of specialised tissues and organs – the derivates of:
• ectoderm• mesoderm• endoderm
blastogenesis
embryonic period
fetal period
Histogenesis, organogenesis
Ontogenesis
• mechanisms operate…at different levels
• cells - differentiation• cell populations - morphogenesis - structure development• cell populations set - morphogenetic system – realizes
structure and function programme in organ or part of the body – basic morphogenetic processes
1. Cell level – differentiation – mesenchymal cell
mesenchymal cell
chondroblast lipoblast fibroblast osteoblast myoblast
cartilage fat
connective tissue, ligaments, tendons
bone muscle
endothelium blood cells
hemocytoblast
Cell level – differentiation – neuroepithelim
2. Cell populations level
• development of structures/ organs - morphogenesis• 1. induction – one cell population induces the change of the
fate in another cell population • epithelial-mesenchymal interactions examples: limbs, lens, nephrons, teethcross-talk• 2. cell-signalling, signalising cell x target cell (must be
sensitive to this signal) paracrine interactions, contact interactions
• induction neuroectoderm / surface ectoderm – lens placode
Induction in gonad – indifferent stageinduction – primordial germ cells/ testes, ovaryinduction – coelomic epithelium / mesenchyme
3. Morphogenetic systems level= group of cell populations relize the developmental
programme
• basic morphogenetic processes - 4 processes play out at the cell population level to essentially create the final organism
• proliferation
• migration
• asociation
• programmed cell death - apoptosis
Morphogenetic system level neural tube differentiation in CNS development
Histogenesis
• EPIBLAST is the maternal of 3 germ layers• ectoderm and endoderm are epithelia• Expression CAM +• mesoderm is connective tissue – primary
mesenchyme• No Expression CAM -
Origin of 3 germ layers
Germ layers derivates
• nervous systeme• senses connectives• skin circulatory s. hematopoesis, immune s. endocrine s.
Epiblast
ectoderm mesoderm endoderm
urogenital sytem
mesenchyme digestive s.respiratory s
Ectoderm and its differentiation1.neuroectoderm (neural tube a neural crest)
2. surface ectoderm
1.neuroectoderm
2. surface ectoderm
neuroectoderm:NT, neural crest placodessurface ectoderm:epidermis
Neural tube – region of the future brain (segmentation- neuromers- brain vesicles)
induction neuroectoderm / surface ectodermplacodes - otic placodes and lens placodes
Neuroectoderm - neural crest – definitive derivates
connectives, cartilage, bone, dermis of the head
cranial nerves ganglia
odontoblasts, Schwann cells melanocytes, C-cells of thyroidautonomic ganglia
adrenal medulla
Ectoderm derivates mediate the contact between body and outer environment
• CNS• PNS• sensory epithelium of the ear, nose, eye• epidermis and its derivates – hairs, nails• glands of the skin, mammary gland• hypophysis• enamel
Endoderm and its differentiation yolk sac roof and wall,
primitive gut
Endoderm-lined cavity and its position during cephalo-caudal folding
sagittal midline section
Endoderm and its derivates
• gastrointestinal tract – epithelium• respiratory sytem – epithelium• parenchyme of the liver, pancreas, thyroid• reticular stroma of tonsils and thymus• epithelium of salivary glands • epithelium of urinary bladder, urethra• epitel of middle ear and Eustachian tube
Mesoderm and its early differentiationaxial, paraxial, intermediate, lateral
Mesoderm – mesenchyme – embryonic connective tissue
Somite differentiationsclerotome, dermatome, myotome
epiteloid arrangement of somitesclerotome – connectives coating spinal cord
dorsolateral cells migrate to the limb bud - muscles
Dorsomedial cells – myotome –trunk muscles
dorsally - dermatom – beneath ectoderm – dermis in the skin
Somites, 42 – 44 pairs . 1.pair in occipital region, 20EDMaterial: paraxial mesodermSegmentation: Notch, WNT, segmentation genesRetinoic acid, FGF8, cranio-caudal gradient
S
Intermediate mesoderm – derivatesurogenital sytem
in cervical, and thoracal region – segmented in nephrotomesabdominal – nefrogenic blastema
Excretory units of kidney and gonad primordium
Lateral mesoderm – splanchnic/ splanchnopleura and somatic/ somatopleura
splanchnopleura – wall of gut (CT, muscle)somatopleura – serous membrane – inner
lining of coelomtransversal section
3week 4week
Mesoderm and its derivates
• connectives (connective tissue proper, cartilage, bone)
• blood• mesothel and endothel– the only epithelia• kidneys• gonads
• mesothel – simple squamous epithel of the visceral peritoneum /splanchnopleura in peritoneal cavity
Tissues family tree
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