组织学与胚胎学课件：Small intestine

1、,Main absorb site: small intestine,why,Small intestine Divided into three parts: duodenum jejunum ileum Function: *digestion *absorption *secreted certain hormones,Plicae circulares,*found only in the small intestine; *epithelium+lamina propria *having a core of lamina propria with capillary network

2、, a central lacteal and few smooth muscle fibers.,Intestinal villi,gland,villus,epithelium,Core of villus,Longitudinal section of small intestine,模式图,H.E. staining,Smooth muscle,Epithelium,* Simple columnar epith.,absorptive cells,goblet cell,striated border （纹状缘）,The inner surface of small intestin

3、e can be greatly enlarged by: * plicae circularesX 3. * villiX 10. * microvilliX 20.,microvilli,微绒毛表面有糖衣，糖衣内含有二肽酶、双糖酶等,小肠吸收细胞模式图,胞质：丰富的滑面内质网，参与形成乳糜微粒 甘油一脂 滑面内质网 甘油三脂 高尔基体 乳糜微粒 脂肪酸 甘油三脂合成酶 释放于细胞侧面 功能： 1.参与消化吸收 2.分泌肠激活酶，激活胰蛋白酶原形成胰蛋白酶 3.参与sIgA的释放过程,goblet cell,5.1.2 lamina propria,中央乳糜管(central lacteal

4、)：腔大,内皮间隙 宽,无基膜,通透性大，运输乳糜微粒 有孔毛细血管：水溶性物质经此入血 少量平滑肌纤维：收缩可缩短绒毛，利于吸收、淋巴和血液运行 小肠腺 淋巴组织,肠腺 1.absorptive cell 2.goblet cell 3.Paneth cell:肠腺所特有，锥形，胞质有粗大的嗜酸性颗粒，分泌防御素和溶菌酶,EM of paneth cell,4.endocrine cell： I细胞：胆囊收缩素-促胰酶素 S细胞：促胰液素 5.stem cell: 位于小肠腺下半部，较小，柱状；增殖分化，更新上皮细胞,Helpful Hint There are specific featu

5、res to look for when attempting to identify a particular portion of the small intestine:Duodenum - duodenal glands in submucosa, some Goblet CellsJejunum - large plicae with many villi, more Goblet CellsIleum - aggregates of Peyers patches, even more Goblet Cells,Lymphatic tissue,Regional difference

6、s in the small intestine,aggregated lymphatic nodule,scattered lymphacytes, solitary lymphatic nodule,Same as in duodenum,Large intestine,盲肠与结肠、直肠 无完整的环行皱襞和绒毛 上皮中杯状细胞非常丰富 大肠腺发达，直而密 外纵肌增厚形成三条结肠带,Appendix,small lumen with usually irregular outline surface epith. with few goblet cells. rare intestinal

7、glands lymphoid nodules located in the lamina propria muscularis mucosa usually incompletely very thin muscularis serosa,自学,Enteroendocrine cells,The endocrine cells contain basal secretory granules and can be divided into 2 types: * open type: cells are adjacent to the lumen of the glands. * close

8、type: cells are separated with the lumen of the glands.,7.Enteroendocrine cells,Basal granules in endocrine cells,close type,open type,Numerous granules of variable size accumulate The granules have an affinity for silver and chromium salts（铬盐）,Important endocrine cells,EC细胞:5-羟色胺（胃大部、小肠、结肠）-促进胃肠运动

9、ECL细胞:组胺（胃底）-促进胃酸分泌 G细胞:胃泌素（幽门、十二指肠） 促进胃酸分泌、粘膜细胞增殖 I 细胞:胆囊收缩素- 促胰酶素（十二指肠、空肠） 促进胰酶分泌、胆囊收缩 S细胞:促胰液素（十二指肠、空肠） 促进胰导管分泌水和HCO3-,Immunological propertiesof digestive tract,Aggregated lymphatic nodules M (microfold cells)cells： These cells are characterized by the presence of numerous basal membrane invagin

10、ations that form pits containing many lymphocytes and macrophages. Function: endocytose antigens and transport them to the underlying macrophages and lymphoid cells lymphocytes Plasma cells,Summary,Master the structure of small and large intestine, especially the structure and functions of absorptiv

11、e cell, small intestinal gland and large intestinal gland. Know the composition and functions of lymphatic tissue of digestive tract. Know gastrointestinal five kinds of endocrine cells (EC cells, ECL cells, G cells, I cells and S cells).,消化系统发生,原始消化管的形成过程,前肠咽、食管、胃、十二指肠上段、 肝、胆、胰、呼吸系统(喉以下) 中肠十二指肠中段横结

12、肠右2/3段 后肠横结肠左1/3段肛管上段,食管的发生,食管： 短延长； 单层上皮复层上皮， 管腔闭锁管腔重现,食管的形成过程,食管狭窄或闭锁,食管腔内过度增生的细胞未凋亡或凋亡不全形成食管狭窄或闭锁。 此畸形也常见于十二指肠的发生。,胃的发生,1.梭形膨大 2.背侧生长快，形成胃大弯； 3.腹侧生长缓慢，形成胃小弯； 4.背系膜生长快，形成向左的网膜囊； 5.胃大弯转向左，胃小弯转向右侧； 6.胃大弯头端膨起，形成胃底。,胃的形成过程,肠的发生（一）,1.中肠袢顶连卵黄管，分头支和尾支 2.以肠系膜动脉为中轴旋转270， 使头支位于左侧，尾支位于右侧,肠的发生（二）,中肠袢突入脐腔， 形成生

13、理性脐疝 头支先退回腹腔， 主要演化为空肠和 回肠，居腹腔中部 尾支后退回，主要 演化为结肠,肠的发生（三）,尾支出现盲肠突盲肠和阑尾的原基 盲肠初位于肝下，后降至右髂窝 脐腔闭锁,先天性脐疝,脐腔未闭锁导致脐部残留一孔与脐腔相通，腹压增高时肠管可从脐部膨出。,胚体,卵黄管异常,梅克尔憩室,脐瘘,脐窦,梅克尔憩室,卵黄管近段未退化，导致距回盲部40-50cm处的回肠壁上残留一指状盲管，为梅克尔憩室,脐粪瘘,卵黄管未闭锁，回肠与脐之间残留一瘘管，为脐粪瘘。 当腹内压增高时，粪便可通过瘘管从脐部溢出。,脐 窦,卵黄管远端部分未闭锁，脐部保留一窦状小凹，常分泌黏液,中肠袢旋转异常,中肠在退回腹腔时，如果未发生旋转、转位不全或反向转位，则为中肠袢旋转异常。 会发生消化管异位，常伴有心、肝、肺和脾的异位。,泄殖腔分隔和直肠形成,泄殖腔的分隔、分化和直肠的发生,后肠末段为泄殖腔 尿囊与后肠间形成尿直肠隔，与泄殖腔膜融合,泄殖腔的分隔、分化和直肠的发生,泄殖腔分隔：腹侧尿生殖窦泌尿生殖管道；背侧原始直肠直肠和肛管上段 泄殖腔膜分隔：腹侧尿生殖膜；背侧肛膜破裂后肛管上下