C8545 Developmental Biology Lesson 3 Early Development of Amphibians and Amniotes Jan Hejátko Laboratory of Molecular Plant Physiology, Department of Functional Genomics and Proteomics, and Functional Genomics and Proteomics of Plants CEITEC Masaryk University, Brno, Czech Republic hejatko@sci.muni.cz, www.ceitec.eu Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation  gastrulation of amphibians (video)  Neurulation  neurulation in Xenopus (video)  Oogenesis in amniotes - chicken  Gastrulation in amniotes – chicken  early and late gastrulation in chicken (video) Outline of Lesson 3 Early Development of Amphibians and Amniotes  Gastrulation in amniotes – chicken  early and late gastrulation in chicken (video)  Formation of extraembryonic tissues in amniotes – chicken Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians Huynh and Johnston., Curr Biol (2004) Kartáčové chromozómy Oogenesis in Xenopus vs. oogenesis in Drosophila Zárodečný váček Vitellogenin in the bloodstream Animal pole Vegetal pole Huynh and Johnston., Curr Biol (2004) Sperm entry in the animal hemisphere determines the future dorsoanterior position Internal Transcribed Spacer (ITS) 5’ External Transcribed Sequence (ETS) 3’ ETS Nuceloli located (approx. 1500) Outside the nucleoli 20K vs. 400 copies in oocytes and somatic cells, respectively Cytosol Nucleus Hormonální stimulace hormony hypofýzy (gonádotropin) Zárodečný váček Intracellular perceived progesterone signal induces oocyte maturation. Progesteron Folicle disassembles, release to oviduct • sperm cell nucleus • centrosome Sperm cell entry Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis formation in amphibians • Completion of meiosis II • Syngamy Prospective ventral pole Prospective dorsal pole Male centrosome Zóna střihu Šedý srpek Motor molecules located along the microtubules Zbytnělá cementová žláza (adhezivní orgán) 16-64 cells: morula Complete cell divisions (including cytokinesis) First 12 rounds of cell divisions at high peace (every 15 min. each) Morus nigra (mulberry) 212 (approx. 4000) cells 128 cells: blastula Dělící rýha Important molecular events precede further development at the midblastula transition (MBT) • Induction of transcription • Acquiring potential of cell motility • Slowing down the cell division cycle Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video) Budoucí předledvina Somite Notochord Leading edge mesoderm Vedoucí okraj mezodermu Fate map of midblastula, as defined by transplantation experiments The invagination during gastrulation starts here Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation in amphibians Blastopor (prvoústa) Budoucí nervová trubice Dorzální IMZ(Spémanův organizátor) Involuting marginal zone Involující marginální zóna (IMZ) Non-involuting marginal zone Neinvolující marginální zóna (NIMZ) Limit of involution Hranice involuce Entry of sperm cell Dorzální okraj (prvoúst) Oblast epibolie (radiální interkalace) Dorzální okraj prvoúst Ventrální okraj prvoúst Žloutková zátka deep marginal cells move anteriorly Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation in amphibians  gastrulation of amphibians (video) Radiální interkalace Mediolaterální interkalace Dorsal IMZ (Spemann organizer) Dorzální IMZ (Spémanův organizátor) Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation  gastrulation of amphibians (video)  Neurulation Neurální brázdička (rýha) Tvořící se neurální val Neurální ploténka Change of the cell shape due to microfilament action Buňky neurální lišty Fůzované neurální valy Místa ohybu Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation  gastrulation of amphibians (video)  Neurulation  neurulation in Xenopus (video) Mezentérium (v dospělosti peritoneum) Ledviny Aorta Somit Struna hřbetní (chorda) Neurální trubice Genitální lišta Epidermis Prvostřevo Coelom Somatopleura Somatic mesoderm Splanchnopleura Splanchnic mesoderm Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation in amphibians  gastrulation of amphibians (video)  Neurulation  neurulation in Xenopus (video)  Oogenesis in amniotes - chicken Infundibulum (nálevka) Magnum Isthmus (úžina) Děloha Vejcovod Vaječník Zárodečný terčík Outline of Lesson 3 Early Development of Amphibians and Amniotes  Oogenesis in amphibians  Blastula formation and dorsoventral axis fomation in amphibians  cleavage of Xenopus zygote (video)  Gastrulation  gastrulation of amphibians (video)  Neurulation  neurulation in Xenopus (video)  Oogenesis in amniotes – chicken  Blastula formation in amniotes - chicken Migrující buňky hypoblastu Rýhovací dutina Žloutek Posteriorní marginální zóna Area opaca Area pellucida Primární hypoblast Sekundární hypoblast Egg laying: 60,000 cells, about 1 mm in diameter Migrující buňky hypoblastu Rýhovací dutina Žloutek Posteriorní marginální zóna Area opaca Area pellucida Primární hypoblast Sekundární hypoblast Köllerův srpek There is a role of graviotropism in the anteroposterior axis formation in birds (endoblast) Blastoderm (blastodisc) Zárodečný terčík Does hypoblast determine the anteroposterior axis of epiblast? Köllerův srpek Outline of Lesson 3 Early Development of Amphibians and Amniotes  Gastrulation in amniotes – chicken Hensenův uzel Area opaca Primitvní proužek Area pellucida Somatický mezoderm Splanchnický mezoderm Střední mezoderm Somity Nervová trubice Outline of Lesson 3 Early Development of Amphibians and Amniotes  Gastrulation in amniotes – chicken  early and late gastrulation in chicken (video) Outline of Lesson 3 Early Development of Amphibians and Amniotes  Gastrulation in amniotes – chicken  early and late gastrulation in chicken (video)  Formation of extraembryonic tissues in amniotes - chicken Extraembryonální coelom Somatopleura Splanchnopleura Endoderm Žloutek Origin of extraembryonic tissue Hlavový ohyb amnionu Ocasní ohyb amnionu Extraembryonální coelom Somatopleura Splanchnopelura Endoderm Žloutek Embryo Střevo Amniová dutina Amnion Alantois Seróza (chorion) Extraembryonální endoderm Future yolk sac Budoucí žloutkový váček Amniová dutina Chorioamniová dutina Vychlýpením zadního střeva vzniká budoucí alantois (splanchnic) uric acid accumulation Chorioalantoidní membrána Alantois Seróza (chorion) Key Concepts  First source of asymmetry originates from the oogenesis both in Drosophila and Xenopus.  In Xenopus, another important source of asymmetry leading to breaking of the virtual radial symmetry of the egg and dorsoventral axis specification is the sperm entry that induces cytoplasm rotation.  These processes result into Speman organizer differentiation and allow specification of the cell fate during blastula formation.  Gastrulation allows further delimitation of the developmental fate.  Amniotes developed terrestrial adaptations that are of extraembryonic origin.