摘要
蒙古绵羊胚胎的原肠、消化及呼吸器官,内分泌腺的原基,发生在交配后的8～30d。胚胎发育到20～21d,胚长4～6mm;到22～23d,胚长7～9mm;到24～30d,胚长10～15mm。交配后8d12h,胚胎原肠呈球形,16d14h,原肠发育成管状,分前肠、中肠及后肠。胚长4～14mm,头侧5对鳃弓逐渐退化,口膜破裂与前肠相通,上下颌及舌已形成。感官及主要内分泌腺的原基也已发生。食道呈管状,胃芽由棱形变成椭圆形。分化出三室,背系膜中有脾芽发生。胚长4～5mm 时,前中后肠呈直管状,到6～9mm,肠襻似“V”字形;胚长10～15mm 时,“V”形肠襻以背系膜为中轴,顺时针旋转180°。胚胎发育到20d,前肠腹面的内胚层发生出1个肝憩室,到22d,肝芽内细胞索交织成网,其中形成静脉导管。到交配后30d,总胆管通向降肠起端。背胰芽发生于前肠背面的内胚层,腹胰芽发生于胆囊管后方的前肠腹面,腹胰芽从前肠右侧伸向背胰芽,合并为胰腺原基。从4mm 长胚胎开始,咽底面发生喉气管沟,进而形成喉气管芽,到胚长15mm,气管芽依次分支形成肺芽原基。
The rudiments of primitive gut digestive and rispiratory organs and the endocrine glandsof Mongolian Sheep embryos develop at 8～30 days agter coitus.Mongolia Sheep embryos at the stage of 20～21 days is 4～6 mm in length,at 22～23days is 7～9 mm,at 24～30 days is 10～15mm.The embryonic gastrula is spherical form at 8 days and 12 hours after coitus,and at 16days and 14 hours is long tubular shape,which can be divided into the fore-gut,the mid-gutand the hind-gut.The 5 pairs of visceral arches of the head side have gradually degenerated when embry-onic length is 4～15mm.The oral plate ruptures to connect with the fore-gut.Maxillarybone,mandibular process and tongue are formed at this stage.Rudiments of the sense organsand the main endocrine glands developed also.The esophagus shows tubular shape.The stomach bud changed from shubbleform intooblong shape,which was diveided into three cavites.The splenic bud arised in the dorsalmesentery.The fore-gut,the mid-gut and the hind-gut showed straigth tubular shapes at 4～5mmembryonic length stage.The gut loop looks like the letter“V” at 6～9mm in length.At 10～15mm length stage,the“V”shaped gut loop revolves 180° clockwise around the dorsalmesenteric axis.At about 20 days of the development,the ventral entoderm of the fore-gut proceeds anhepatic diverticulum.At 22 days,the cell cords in the liver bud interweave into retia each oth-er,in which forms the ductus renosus.The common bile duct enters to the beginning end ofthe descending gut loop at 30 days after coitus.The dorsal pancreas develops into the dorsalentoderm of the fore-gut,and the ventral pancreas develops into the ventral enoderm behindthe cystic ducy.The ventral oancreas extends toward the dorsal pancreas from the right sideof fore-gut,and to merge into the pancreatic rudiment.Started at 4 mm embryonic length stage,the laryngeal tracheal groove appears on thepharynx floor,then to form a bud.At 15mm embryonic length,the tracheal bud bifurcatesone by one to form the lung-rudiment.
关键词
绵羊
胚胎
消化
呼吸
器官
mongolian sheep
embryo
digestion
respiration
rudiment
development
