...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >The developing renal, reproductive, and respiratory systems of the African elephant suggest an aquatic ancestry
【24h】

The developing renal, reproductive, and respiratory systems of the African elephant suggest an aquatic ancestry

机译：非洲象不断发展的肾脏，生殖和呼吸系统表明其水生祖先

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The early embryology of the elephant has never been studied before. We have obtained a rare series of African elephant (Londonta africana) embryos and fetuses ranging in weight from 0.04 to 18.5 g estimated gestational ages 58-166 days (duration of gestation is approximately equals 660 days). Nephrostomesi, a feature of aquatic vertebrates, were found in the mesonephric kidneys at all stages of development whereas they have never been recorded in the mesonephric kidneys of other viviparous mammals. The trunk was well developed even in the earliest retus. The testes were intra-abdominal, and there was no evideuce of a gubernaculum, pampiniform plexus, processus vaginalis, or a scrotum, confirming that the elephant, like the dugong, is one of the few primary testicond mammals. The palaeontological evidence suggests that the elephant's ancestors were aquatic, and recent immunological and molecular evidence shows an extremely close affinity between present-day elephants and the aquatic Sirenia (dugong and manatees). The evidence from our embryological study of the elephant also suggests that it evolved from an aquatic mammal.
机译：大象的早期胚胎学从未被研究过。我们获得了一系列稀有的非洲象（Londonta africana）胚胎和胎儿，其体重在0.04至18.5 g之间，估计的胎龄为58-166天（妊娠持续时间大约等于660天）。在水生脊椎动物的所有发育阶段都发现了水生脊椎动物的肾功能，而在其他胎生哺乳动物的中肾中从未发现过肾功能。即使在最早的时候，躯干也发育良好。睾丸是腹腔内的，没有任何蛛网膜，绒毛状丛，阴道突或阴囊的证据，这证明象儒艮一样，大象是少数受试的哺乳动物之一。古生物学证据表明，大象的祖先是水生的，最近的免疫学和分子证据表明，当今的大象与水生的海妖属（杜鹃和海牛）之间有着极为密切的亲和力。我们对大象进行胚胎学研究的证据也表明，大象是从水生哺乳动物进化而来的。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号