[医学保健]泌尿生殖系统发生

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1、精品PPT课件浏览免费下载后可以编辑修改。http://www.docin.com/jn-lxhhttp://www.doc88.com/lianer2012http://www.baidu.com/http://www.google.com/http://www.sogou.com/医学精品课件最权威的课件资料，免费在线阅读分享，下载后可以编辑修改。泌尿生殖系统发生（Dvelopmentoftheurogenitalsystem）原基：生肾节生殖腺嵴（内）演变：生肾索尿生殖嵴中肾嵴（外）Intermediatemesodermnephrot

2、omeUrogentialridgeGenitalridgeMesonephricridgeNephrogeniccord一．Developmentofurinarysystem泌尿系统的发生（一）developmentofkidneysandureter肾和输尿管的发生：经前肾→中肾→后肾，顺次从颈→尾发生。Duringembryonicdevelopment,threesetsofnephricstructuredevelopincraniocaudalsuccessionfromtheintermediatemesoderm.These

3、calledthecervicalnephrotomes,themesonephroi,andthemetanephroiordefinitivekidneys.1．前肾（pronephros）：4周初部位：eachoffivetosevenpairedcervicalsegmentsofintermediatemesoderm颈部第5-7体节外侧生肾节内。构成：前肾小管pronephrictubule和前肾管pronephricduct。结局：无泌尿功能，4周末退化，前肾管向尾侧延伸成中肾管。Thecervicalnephrotomesar

4、etransientandnonfunctional.Earlyinthefourthweek,eachoffivetosevenpairedcervicalsegmentsofintermediatemesodermgivesrisetoasmall,hollowballofepitheliumcalledanephricvesicleornephrotome(fig10-2A).Manyauthorsrefertotheseriesofcervicalnephrotomesoneachsideasapronephrosbecausethe

5、yresemblethefuncionalembryonicpronephroiofsomelowervertebrates.Inhumans,however,theseunitsdonotdifferentiateintotheprimitivebutfunctionalexcretorystructuresofatruepronephros,butinsteadceasedevelopingatthenephrotomeastageandthereforeseemtobenonfunctionalandvestigial.Theydisa

6、ppearbyday24or252、中肾(mesonephros)：4周末部位：第14—2对体节外侧的中肾嵴内。构成：mesonephrictubule中肾小管，约80对。mesonephricduct中肾管（wolffianduct）—fromthoracicregiontocloacaandthengrowtoandfusewiththeventrolateralwallsofthecloacaonday26(原前肾管，尾端通入泄殖腔)。结局：有短暂功能活动，中肾小管大部分退化，中肾管及尾侧中肾小管演变为男性排精管道。Thelateral

7、tipofeachmesonephrictubulefuseswiththemesonephricduct,thusopeningapassagefromtheexcretoryunitstothecloaca.Themesonephricexcretoryunitsarefunctionalbetweenabout6and10weeksandproducesmallamountsandthenregress.Asdiscussedlater,themesonephricductsalsoregressinthefemale.Inthemal

8、ehoweverthemesonephricductsplusafewmodifiedmesonephrictubulespersistandformimporta