Embriologia: - Fertilização - Clivagem - Formação do blastocisto - Gastrulação

Transcrição

1 Embriologia: - Fertilização - Clivagem - Formação do blastocisto - Gastrulação Formação das três camadas germinativas Padrões de gastrulação em diferentes organismos Aspectos conservados x não conservados: molecular e morfológico - Neurulação Primária e secundária Sinais moleculares na indução e padronização (estabelecimento de assimetrias) Assimetria antero-posterior Assimetria dorso-ventral e funcionalidade -Somitogênese e derivados mesodermais Tipos de mesoderma Somitos: considerações morfológicas, interações celulares e (controle temporal) -Formação dos membros Tecidos envolvidos Sinais moleculares Estabelecimento de assimetrias

2 A phylogeny of chordate evolution. (a) A phylogenetic tree depicting the likely relationships between chordates and other animals, timing of genome amplifications (solid circles), and origin of novel characteristics. Phyla are in capitals; Porifera includes sponges; Cnidaria includes jellyfish and hydra; Echinodermata includes sea stars and sea urchins and Hemichordata includes marine acorn worms. (b) Genome size (Mb) and (c) estimated gene number of sequenced animal genomes are represented by bars. Cañestro et al. Genome Biology :208 doi: /gb

3 Formação do Blasocisto Massa celular interna ou embrioblasto Epiblasto Hipoblasto 7 dias Capilar Massa celular externa ou trofoblasto Capilar Trofoblasto sincicial glândula

4 A Linha Primitiva Nó primitivo Poço primitivo Sulco primitivo Linha Primitiva

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6 Gastrulação: Ectoderma Mesoderma Endoderma Larsen, Human Embriology, 6 th Ed.

7 Comprometimento de Territórios lineage tracing

8 Mudanças Morfológicas Gastrulação no Embrião Humano

9 Mudanças Morfológicas : Extensão convergente

10 Mudanças Teciduais : Transição Epitélio- Mesenquimal Antin lab

11 Chordados

12 Phylum Chordata Vertebrates, sea squirts or tunicates, lancelets such as Amphioxus. Name: "Chord" means "string", referring to the nerve cord and/or notochord. Chief characteristics: Chordates have the following features at some point in their life (although in some cases, these features may be present only in the embryo): Bilateral symmetry. Gill slits. These slits are a series of openings that connect the inside of the throat to the outside of the "neck". Dorsal nerve cord (sometimes called a spinal cord). The nerve cord runs down the "back", connecting the brain with the muscles and other organs. Notochord. A stiff cartilaginous rod which supports the nerve cord. Post-anal tail. This is an extension of the body past the anal opening. Blood that circulates forward in a main ventral vessel and backward in a dorsal vessel. Branchiostoma, a non-vertebrate chordate. Length 3-5 cm. Chief characteristics: Lancelets resemble a small, colorless anchovy fillet, without obvious eyes or lateral fins. Worm-like. Has segmented axial muscles, gill slits, a dorsal hollow nerve cord, a notochord, and a postanal tail. There is nothing resembling a vertebral column. No solid skeleton.

13 O Endoderma e seus derivados Tubo Digestivo Primitivo Sistema Digestório Sistema Respiratório

14 O Mesoderma e seus derivados Notocorda Paraxial Somitomeros Somitos Esclerotomo Dermomiótomo Dermátomo Intermediario: Sist. Urogenital Placa lateral Somatopleura Esplancnopleura Miótomo

15 O Ectoderma e seus derivados Neuroectoderma Placa Neural Sistema Nervoso Central Crista Neural Sistema Nervoso Periférico Músculos Ossos da Face e Pescoço Melanócitos... Ectoderma não Neural Epiderme

16 Notocorda Larsen, Human Embriology, 6 th Ed.

17 Mesoderma

18 Neurulação Ectoderma não neural: epiderme Ectoderma Neural: Sistema Nervoso

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20 Neurulação e Somitogênese

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23 Mus musculus

24 Gastrulação Gallus gallus

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30 Gastrulação Xenopus laevis

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34 Gastrulação em Xenopus laevis

35 Epibolia em Xenopus laevis

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37 Gastrulação: Aspectos Moleculares

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40 Transplante de organizador de Spemann: Teoria da Indução Neural

41 Transplante de nódulo de Hensen:

42 Busca de fatores secretados pelo organizados de Speman: Biblioteca de cdnas: testes funcionais usando embriões selvagens ou ventralizados Fatores encontrados: Chordin, Nogin e Follistatin. Antagonistas de BMPs NH3 COOH

43 BMP2/4 Chordin BMP e Chordin são expressos em lados opostos BMP: inibe o destino neural Chordin: inibe a atividade de BMP

44 Gastrulação em Drosophila

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46 Desenvolvimento do Sistema Nervoso Central (Ectoderma) Atlas of Drosophila Development, Volker Hartenstein 1993 Cold Spring Harbor Press

47 D Dpp DE Sog NE MES V

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49 The Coiled Spring - E. Bier

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51 Ethan Bier s Coiled Spring

52 Conservação

53 FIGURE 3. Regional specificity of organizer induction. Transplantations were carried out using newt neurulae (left) as donors. Neural plate was removed at various A P levels (left) and the underlying archenteron roof was transplanted into the blastocoel of a host gastrula (not shown). The resulting animals (right) showed inductions whose character varied as a function of the A P level of the transplanted mesoderm or mesendoderm. (a) Balancers induced by anterior mesendoderm. (b) Head with eyes and forebrain induced by prechordal plate. (c) Posterior head structures (hindbrain, otic vesicle) induced by chordamesoderm. (d) Trunk tail structure induced by posterior chordamesoderm. Modified from Ref. 14.

54 FIGURE 1. Two-inhibitor model for antero posterior neural induction. (a) Nieuwkoop two-signal model. During gastrulation ectoderm is neuralized by an activator released from presumptive prechordal plate mesoderm, conferring anterior character. As gastrulation proceeds, chordamesoderm comes to underlie activated neuroectoderm and releases a transformer in an A P graded fashion, conferring increasingly posterior neural character (hindbrain, spinal cord). (b) Two-inhibitor model. BMP and WNT signals in the ectoderm prevent neuralization. Anterior endoderm (not shown) and prechordal plate release WNT and BMP inhibitors, inducing anterior neuroectoderm. More posteriorly in chordamesoderm, WNT inhibitors are progressively less expressed creating an A P WNT signalling gradient, which posteriorizes and patterns neuroectoderm. Eivers 2009