Embriologia – Gravidez e Gestação
Autor: Natal Skeptics | Publicado: 2011-10-27T11:23:00-07:00

<!--[if gte mso 9]>     Normal   0         21         false   false   false      PT-BR   ZH-CN   X-NONE                                                         MicrosoftInternetExplorer4                                                   <![endif]--><!--[if gte mso 9]>  <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true"
  DefSemiHidden="true" DefQFormat="false" DefPriority="99"
  LatentStyleCount="267">   <w:LsdException Locked="false" Priority="0" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Normal"/>   <w:LsdException Locked="false" Priority="9" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="heading 1"/>                                                         <w:LsdException Locked="false" Priority="10" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Title"/>      <w:LsdException Locked="false" Priority="11" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Subtitle"/>   <w:LsdException Locked="false" Priority="22" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Strong"/>   <w:LsdException Locked="false" Priority="20" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Emphasis"/>   <w:LsdException Locked="false" Priority="59" SemiHidden="false"
   UnhideWhenUsed="false" Name="Table Grid"/>      <w:LsdException Locked="false" Priority="1" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="No Spacing"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 1"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 1"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 1"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 1"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 1"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 1"/>      <w:LsdException Locked="false" Priority="34" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="List Paragraph"/>   <w:LsdException Locked="false" Priority="29" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Quote"/>   <w:LsdException Locked="false" Priority="30" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Intense Quote"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 1"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 1"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 1"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 1"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 1"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 1"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 1"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 1"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 2"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 2"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 2"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 2"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 2"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 2"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 2"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 2"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 2"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 2"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 2"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 2"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 2"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 2"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 3"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 3"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 3"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 3"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 3"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 3"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 3"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 3"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 3"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 3"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 3"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 3"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 3"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 3"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 4"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 4"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 4"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 4"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 4"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 4"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 4"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 4"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 4"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 4"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 4"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 4"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 4"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 4"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 5"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 5"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 5"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 5"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 5"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 5"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 5"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 5"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 5"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 5"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 5"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 5"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 5"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 5"/>   <w:LsdException Locked="false" Priority="60" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Shading Accent 6"/>   <w:LsdException Locked="false" Priority="61" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light List Accent 6"/>   <w:LsdException Locked="false" Priority="62" SemiHidden="false"
   UnhideWhenUsed="false" Name="Light Grid Accent 6"/>   <w:LsdException Locked="false" Priority="63" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 1 Accent 6"/>   <w:LsdException Locked="false" Priority="64" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Shading 2 Accent 6"/>   <w:LsdException Locked="false" Priority="65" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 1 Accent 6"/>   <w:LsdException Locked="false" Priority="66" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium List 2 Accent 6"/>   <w:LsdException Locked="false" Priority="67" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 1 Accent 6"/>   <w:LsdException Locked="false" Priority="68" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 2 Accent 6"/>   <w:LsdException Locked="false" Priority="69" SemiHidden="false"
   UnhideWhenUsed="false" Name="Medium Grid 3 Accent 6"/>   <w:LsdException Locked="false" Priority="70" SemiHidden="false"
   UnhideWhenUsed="false" Name="Dark List Accent 6"/>   <w:LsdException Locked="false" Priority="71" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Shading Accent 6"/>   <w:LsdException Locked="false" Priority="72" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful List Accent 6"/>   <w:LsdException Locked="false" Priority="73" SemiHidden="false"
   UnhideWhenUsed="false" Name="Colorful Grid Accent 6"/>   <w:LsdException Locked="false" Priority="19" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Subtle Emphasis"/>   <w:LsdException Locked="false" Priority="21" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis"/>   <w:LsdException Locked="false" Priority="31" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Subtle Reference"/>   <w:LsdException Locked="false" Priority="32" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Intense Reference"/>   <w:LsdException Locked="false" Priority="33" SemiHidden="false"
   UnhideWhenUsed="false" QFormat="true" Name="Book Title"/>         <![endif]--><!--[if gte mso 10]> 
 /* Style Definitions */
 table.MsoNormalTable
 {mso-style-name:"Tabela normal";
 mso-tstyle-rowband-size:0;
 mso-tstyle-colband-size:0;
 mso-style-noshow:yes;
 mso-style-priority:99;
 mso-style-qformat:yes;
 mso-style-parent:"";
 mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
 mso-para-margin-top:0cm;
 mso-para-margin-right:0cm;
 mso-para-margin-bottom:10.0pt;
 mso-para-margin-left:0cm;
 line-height:115%;
 mso-pagination:widow-orphan;
 font-size:11.0pt;
 font-family:"Calibri","sans-serif";
 mso-ascii-font-family:Calibri;
 mso-ascii-theme-font:minor-latin;
 mso-hansi-font-family:Calibri;
 mso-hansi-theme-font:minor-latin;}
 <![endif]-->  
Após o coito, as prostraglândinas encontradas no sêmen induzem às contrações vaginais levando o esperma a tuba uterina onde se encontra com o ovócito secundário (processo que leva em torno de 15 horas). Quando o esperma se encontra com o ovócito ele caminha em direção a membrana plasmática do óvulo que é protegida pela zona pelúcida e as células foliculares, onde finalmente realiza uma conexão entre uma proteína localizada no acrossomo(cabeça do esperma) chamada fertilizina, com uma proteína encontrada na membrana plasmática do ovócito chamada ZP3, despolarizando a membrana impedindo que outros espermas façam essa conexão. Esse processo faz com que o esperma injete o pronucleo masculino causando a fusão dos gametas transformando-os em zigoto dando início ao processo de clivagem (segmentação) que dura cerca de seis dias. No inicio da clivagem a célula passa por sucessivas mitoses formando blastômeros (células somáticas que por si só podem gerar qualquer outra), passando pelo estágio de mórula (16 células) até tornar-se blástula. Dessa forma, se um espermatozóide fecundar um único ovócito e durante a clivagem ocorrer uma divisão da mórula em duas culturas de células, formará dois indivíduos, clones um do outro (gêmeos univitelinos ou monozigóticos) já que os blastômeros em questão são células somáticas. Caso dois ovócitos sejam produzidos e cada um seja fecundado por um espermatozóide, ocorrerá a formação de dois indivíduos diferentes um do outro (gêmeos bivitelinos ou dizigóticos). A clivagem é controlada pela quantidade de vitelo presente no ovo, mamíferos tem pouco vitelo, pois possui gestação uterina fazendo com que os nutrientes sejam passados pela mãe.Após a clivagem, e nidação ocorre o processo de gastrulação, onde os tecidos germinativos se desenvolvem para formar cada orgão do corpo. O ectoderma originará o sistema nervoso central e periférico, cérebro, tubo neural, cavidade oral e nasal, epiderme e seus anexos (cabelo, unha pelos), glândulas sudoríparas e mamárias.O mesoderma formará os ossos, tecido conjuntivo, cartilagem, derme, coração, vasos sanguíneos, rins e notocorda (que posteriormente dará origem a coluna vertebral)O endoderma produzirá o fígado, pâncreas, tireóide, bexiga, intestino e trato respiratório.Depois disso ocorrerá a Neurulação, onde acontece a maturação do individuo e formação do SNC. Sexto dia após o inicio da clivagem -&gt; Nidação
Primeiro mês -&gt; coração começa a bater
Segundo mês -&gt; membros desenvolvem-se e já possível saber o sexo ou alguma doença
Terceiro mês-&gt; feto em miniatura (a partir daqui diminui a sensibilidade do feto, inclusive á radiação.)
Do quarto ao sexto-&gt; crescimento e maturação dos orgãos
Sétimo ao oitavo-&gt; ”vivo”