鸡胚胎龄的发育与分期

The Stages and Development of Embryonic Age of the Chick

对鸡胚胎龄的形态发育与营养供应关系的研究表明,鸡在个体发生的胚胎发育中,显示了禽类系统发生的信息,从水生到陆生的形态进化分期:如胚层期是从原肠胚到三胚层的形成,胚层以渗透方式获得营养并进行厌氧呼吸。鳃型期是头侧出现四对鳃弓,心管原基开始跳动,为胚肋的血液循环,营养及气体交换建立了基础。趾蹼期是肢芽末端分化成蹼状。爪型期是以趾同蹊膜退化爪甲出现为特征,胚胎从脐肠系膜动静脉进行物质及气体交换。雏型期是雏胚开始吞噬并吸收来自浆羊膜道的营养物质,促进了雏儿消化系统、喙、翅、爪及羽毛的发育。孵化到18天,雏儿可以从气室进行气体交换。雏型期的发育为破壳后雏鸡的本能行为建立了生态学基础。

Development of the chick embryo suggests evolution of the birds. Formation of primitve gut and mesoderm is germ Layer stage, the embryos attain nutrition in the way of osmotic action. When the embryos appear4 pairs of viceral archs, they develop to the visceral arch stage, contraction of the heart duct establishes the base of embryonic circulation of blood. When terminal ends of the Irmb bud change into web—form, they are called web—toe stage. The web—membranes disappear, then appear the claws, which is called the claw—type stage. At the two stages their nutritions are provided by ompholo—mesenteric artery and vein. Because the beak and digestive duct begin the functioning, the embryos can swallow nutrition to coming from the sero—amniotic way, this is chicken type stagc.