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Histogenesis 151 Course 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 Histogenesis, organogenesis fetal period 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 cartilage lipoblast fat fibroblast osteoblast myoblast bone muscle hemocytoblast endothelium blood cells connective tissue, ligaments, tendons 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, teeth cross-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 stage induction – primordial germ cells/ testes, ovary induction – 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 Epiblast ectoderm • nervous systeme • senses • skin mesoderm urogenital sytem mesenchyme connectives circulatory s. hematopoesis, immune s. endocrine s. endoderm digestive s. respiratory s Ectoderm and its differentiation 1.neuroectoderm (neural tube a neural crest) 2. surface ectoderm 1.neuroectoderm 2. surface ectoderm neuroectoderm: NT, neural crest placodes surface ectoderm: epidermis Neural tube – region of the future brain (segmentation- neuromers- brain vesicles) induction neuroectoderm / surface ectoderm placodes - 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 thyroid autonomic 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 differentiation axial, paraxial, intermediate, lateral Mesoderm – mesenchyme – embryonic connective tissue Somite differentiation sclerotome, dermatome, myotome epiteloid arrangement of somite sclerotome – 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, 20ED Material: paraxial mesoderm Segmentation: Notch, WNT, segmentation genes Retinoic acid, FGF8, cranio-caudal gradient S Intermediate mesoderm – derivates urogenital sytem in cervical, and thoracal region – segmented in nephrotomes abdominal – 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 coelom transversal 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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