牙 的 发 育

第二章牙的发育 Chapter 2 Development of Teeth Designed and produced by Dr. Wang Li 1

概述 牙及其支持组织是从上下颌突和额鼻突的外胚层及外胚间叶细胞发育而来 牙齿发育是一长期 复杂的生物学过程 牙齿发育是一个连续的过程, 包括牙胚的发生 牙体组织形成和牙齿的萌出 Designed and produced by Dr. Wang Li 2

第一节牙胚的发生和分化 Designed and produced by Dr. Wang Li 3

牙胚的发生和分化 原发性上皮带 : Primary epithelial band 胚胎第 5 周 Designed and produced by Dr. Wang Li 4

牙胚的发生和分化 原发性上皮带 : Primary epithelial band 胚胎第 5 周 Designed and produced by Dr. Wang Li 5

牙胚的发生和分化 原发性上皮带 : Primary epithelial band Designed and produced by Dr. Wang Li 6

牙胚的发生和分化 胚胎第 7 周 前庭板 Vestibular lamina ( 唇颊侧 ) 前庭沟 Vestibular groove 原发性上皮带 Primary epithelial band 牙板 Dental lamina ( 舌腭侧 ) 牙胚 Tooth germ Designed and produced by Dr. Wang Li 7

牙胚的发生和分化 Vestibular lamina & Dental Lamina Vestibular lamina Dental Lamina Designed and produced by Dr. Wang Li 8

牙胚的发生和分化 Vestibular lamina & Dental Lamina Designed and produced by Dr. Wang Li 9

牙胚的发生和分化 未来的上颌 发育中的舌 未来的下颌 Designed and produced by Dr. Wang Li 10

牙胚的发生和分化 Designed and produced by Dr. Wang Li 11

牙胚的发生和分化 Designed and produced by Dr. Wang Li 12

牙胚的发生和分化 牙板上皮 外胚间充质细胞 Designed and produced by Dr. Wang Li 13

牙胚的发生和分化 牙胚的组成 : 成釉器 Enamel organ 牙乳头 Dental papilla 牙囊 Dental sac 口腔外胚层 外胚间叶 外胚间叶 牙釉质牙髓 牙本质 牙骨质 牙周膜 固有牙槽骨 Designed and produced by Dr. Wang Li 14

成釉器的发育 : 成釉器的发育是一个 连续的过程, 可分为 三个时期 Bud stage 蕾状期 帽状期 钟状期 Cap stage Designed and produced by Dr. Wang Li Bell stage 15

蕾状期 (bud stage) 胚胎第八周 牙板上皮增生, 形成上皮芽, 形如花蕾 上皮细胞类似基底细胞, 未出现分化 上皮下方及周围外胚间充质细胞增生 牙弓每个象限内, 最先发生的成釉器有 4 个 乳牙胚第 10 周发生, 恒牙胚第 4 个月形成 Designed and produced by Dr. Wang Li 16

蕾状期 (bud stage) Designed and produced by Dr. Wang Li 17

蕾状期 (bud stage) 上颌突 发育中的舌 Designed and produced by Dr. Wang Li 18

蕾状期 (bud stage) Designed and produced by Dr. Wang Li 19

蕾状期 (bud stage) 牙蕾 Designed and produced by Dr. Wang Li 20

蕾状期 (bud stage) Designed and produced by Dr. Wang Li 21

蕾状期 (bud stage) 舌 发育中的下颌骨 Designed and produced by Dr. Wang Li 22

蕾状期 (bud stage) Designed and produced by Dr. Wang Li 23

蕾状期 (bud stage) Designed and produced by Dr. Wang Li 24

帽状期 (cap stage) 增殖期 胚胎第 9-10 周 Designed and produced by Dr. Wang Li 25

帽状期 (cap stage) Designed and produced by Dr. Wang Li 26

帽状期 (cap stage) 成釉器上皮细胞分化为三层 : 外釉上皮层 (outer enamel epithelium) 星网状层 (stellate reticulum) 内釉上皮层 (inner enamel epithelium) 外胚间充质分化形成 : 牙乳头 (dental papilla) 牙囊 (dental sac) Designed and produced by Dr. Wang Li 27

帽状期 (cap stage) 前庭板 牙板 唇 舌 牙胚 发育中的下颌骨 Designed and produced by Dr. Wang Li Meckle 软骨 28

帽状期 (cap stage) 前庭板 牙囊 牙板 牙乳头 Designed and produced by Dr. Wang Li 29

帽状期 (cap stage) 星网状细胞 外釉上皮层 内釉上皮层 Designed and produced by Dr. Wang Li 牙乳头 30

帽状期 (cap stage) Designed and produced by Dr. Wang Li 31

帽状期 (cap stage) Designed and produced by Dr. Wang Li 32

帽状期 (cap stage) Designed and produced by Dr. Wang Li 33

帽状期 (cap stage) Designed and produced by Dr. Wang Li 34

钟状期 (bell stage) 组织分化和形态分化期 胚胎第 11-12 周成釉器进入成熟期凹面的形状已确定 Designed and produced by Dr. Wang Li 35

钟状期 (bell stage) 细胞分化为四层 : 外釉上皮 (outer enamel epithelium) 内釉上皮 (inner enamel epithelium) 早期成釉细胞 星网状层 (stellate reticulum) 中间层 (stratum intermedium) Designed and produced by Dr. Wang Li 36

钟状期 (bell stage) 颈环 Designed and produced by Dr. Wang Li 37

钟状期 (bell stage) 外釉上皮 单层立方状细胞 借牙板与口腔上皮相连 胞浆少, 含有游离核糖体 少量粗面内质网及线粒体 连接复合体 钟状晚期形成皱褶间充质细胞进入, 内含毛细血管 Designed and produced by Dr. Wang Li 38

钟状期 (bell stage) 牙囊 星网状层 Designed and produced by Dr. Wang Li 外釉上皮 39

钟状期 (bell stage) 内釉上皮 单层细胞与牙乳头相邻, 半桥粒连接到基板 从牙颈部到牙尖, 细胞分化程度各异 矮柱或立方状, 核大居中, 高尔基复合体近中间层细胞, 线粒体分布在其它部分 成釉细胞 (ameloblast) 高柱状, 高 40μm 直径 4-5 μm, 与中间层以桥粒相连 Designed and produced by Dr. Wang Li 40

钟状期 (bell stage) 内釉上皮 分泌开始前, 细胞器重新定位 核远离基底膜 高尔基复合体增大, 向基底膜端移动, 位于核侧面和细胞体的中心 粗面内质网数量明显增加 线粒体近中间层一端 终棒 terminal web Designed and produced by Dr. Wang Li 41

钟状期 (bell stage) 中间层细胞 牙乳头 星网状层 内釉上皮 Designed and produced by Dr. Wang Li 42

钟状期 (bell stage) 颈环 cervical loop 内釉上皮与外釉上皮连接处 在上皮根鞘的发生中起很重要的作用 Designed and produced by Dr. Wang Li 43

钟状期 (bell stage) 外釉上皮 星网状层 牙乳头 牙囊 内釉上皮 颈环 Designed and produced by Dr. Wang Li 44

钟状期 (bell stage) 星网状层 stellate reticulum 外釉上皮和中间层之间 细胞为星形, 有长的突起细胞器数量稀少 合成氨基葡萄糖分泌的细胞之间 细胞间充满富有蛋白的黏液样液体, 对内釉上皮有营养和缓冲作用, 保护成釉器 釉质形成时, 该层细胞萎缩 内 外釉细胞间距缩短, 便于输送营养 Designed and produced by Dr. Wang Li 45

钟状期 (bell stage) 牙囊 星网状层 牙乳头 中间层细胞 外釉上皮 Designed and produced by Dr. Wang Li 内釉上皮 46

钟状期 (bell stage) 中间层 stratum intermedium 内釉上皮与星网状层之间 2-3 层扁平的细胞, 核卵圆或扁平 钟状早期, 胞核居中, 细胞器数量不多 钟状晚期, 细胞间隙增大充满微绒毛, 细胞器数量增多, 酸性粘多糖及糖原沉积 具有较高的碱性磷酸酶活性, 与釉质形成有关 Designed and produced by Dr. Wang Li 47

钟状期 (bell stage) 牙囊 星网状层 中间层细胞 外釉上皮 牙乳头 Designed and produced by Dr. Wang Li 内釉上皮 48

钟状晚期 (late bell stage) 牙本质 成牙本质细胞 Designed and produced by Dr. Wang Li 49

钟状晚期 (late bell stage) 牙本质 成牙本质细胞 Designed and produced by Dr. Wang Li 50

钟状期 (bell stage) 磨牙成釉器 Designed and produced by Dr. Wang Li 51

成釉器的发育 成釉器发育过程中的暂时性结构 : 釉结 (enamel knot) 釉索 (enamel cord) 釉龛 (enamel niche) Designed and produced by Dr. Wang Li 52

釉结 (enamel knot) 作用 : 可能是调节细胞分化和牙形态发生的信号中心 Designed and produced by Dr. Wang Li 53

釉索 (enamel cord) 作用 : 可能参与决定牙尖的早期位置 Designed and produced by Dr. Wang Li 54

釉龛 (enamal niche) Designed and produced by Dr. Wang Li 55

二 牙乳头 牙乳头的细胞为未分化的间充质细胞 钟状期, 在内釉上皮的诱导下牙乳头外层细胞分化出高柱状的成牙本质细胞 在切缘和牙尖部为柱状, 在牙颈部为立方状 牙乳头在牙齿发育中起重要的作用 Designed and produced by Dr. Wang Li 56

牙乳头 牙乳头在牙发育中的作用 : 决定牙形状 Designed and produced by Dr. Wang Li 57

三 牙囊 在成釉器的外周, 外胚间充质组织呈环状排列, 更多的胶原纤维充满在牙囊成纤维细胞之间, 并环绕着成釉器和牙乳头的底部 牙囊中含有丰富的血管, 以保证组织形成所需要的营养 Designed and produced by Dr. Wang Li 58

恒牙牙胚的发育 乳牙牙胚形成后, 在其舌侧, 从牙板游离端下缘出现新的牙蕾, 形成相应的恒牙牙胚 Designed and produced by Dr. Wang Li 59

恒牙牙胚的发育 在乳磨牙牙胚形成之后, 牙板的远中端继续向远中生长, 第一恒磨牙的成釉器从牙板后方的游离端向远中生长而形成 牙板向远中增生延长, 与上下颌弓的长度相协调, 对下颌升支的发育和上颌结节处恒牙胚的发生起重要作用 Designed and produced by Dr. Wang Li 60

恒牙牙胚的发育 第一恒磨牙牙胚是在胚胎第 4 个月形成 第二恒磨牙牙胚是在出生后一年形成 第三恒磨牙牙胚是在 4 5 岁时形成 牙胚的活动期从胚胎发育的第 6 周开始, 持续到出生后第 4 年, 整个活动期约 5 年的时间 Designed and produced by Dr. Wang Li 61

四 牙板的结局 Designed and produced by Dr. Wang Li 62

牙板的结局 Designed and produced by Dr. Wang Li 63

牙板的结局 Serre s 上皮剩余 Designed and produced by Dr. Wang Li 64