Developmental Biology 第八章胚后生长及衰老 Post-embryonic Growth and Aging
Developmental Biology 第八章 胚后生长及衰老 Post-embryonic Growth and Aging
Developmental Biology 组织、器官、个体的生长 动物生长的主要特点 胚胎发育早期生长不明显或缓慢; 生长主要发生在个体的维形建立之后; 不同组织器官的生长速度不同
Developmental Biology 动物生长的 主要特点 ➢ 胚胎发育早期生长不明显或缓慢； ➢ 生长主要发生在个体的雏形建立之后； ➢ 不同组织器官的生长速度不同。 一、组织、器官、个体的生长
Developmental Biology 生长的策略 e.g, many Axon of neuron e.g. bone, tissues cartilage Cell Cell Growth by Fig 14.1 The three main strategies multiplication enlargement accretion for growth in vertebrates. The most common mechanism is cell proliferation -growth followed by division. A second o strategy is cell enlargement, in which cells increase their size without dividing a third strategy is to increase size by accretionary growth, such as matrix secretion 号‖◎ 损伤或刺激可诱导细胞增殖或生长: matrIx ↓ 如将大鼠肝脏切除2/3,剩余部分增殖 ○|使肝脏恢复原来的大小;切除肾的 部分,剩余部分主要通过细胞增大而 增大。 在正在生长的组织中,生长速度决 定于细胞的增殖和凋亡的速度
Developmental Biology 生长的策略 Axon of neuron e.g., bone, cartilage e.g., many tissues 损伤或刺激可诱导细胞增殖或生长： 如将大鼠肝脏切除2/3,剩余部分增殖 使肝脏恢复原来的大小；切除肾的一 部分，剩余部分主要通过细胞增大而 增大。 在正在生长的组织中，生长速度决 定于细胞的增殖和凋亡的速度
Developmental Biology 细胞增殖受内外因素的控制 Fig. 14.2 The eukaryotic cell cycle After mitosis(M), the daughter cells can either enter a resting phase(Go), in which they effectively withdraw from the cell Resting cycle, or proceed through Gt to the phase of DNA synthesis(S). This is followed by DIVISIOn G2, and then by mitosis. Cell growth occurs throughout G1, S, and G2. The decision to enter Go or to proceed through G1 IGrowth may be controlled by both intracellular factors status and extracellular signals, such as growth factors. Cells such as neurons cephas and skeletal muscle cells, which do not divide after differentiation are permanently in Go During cleavage of fertilized eg there are virtually no G-phase
Developmental Biology 细胞增殖受内外因素的控制 During cleavage of fertilized eggs, there are virtually no G-phase
Developmental Biology 果蝇胚胎早期发育中细胞的分裂特点 果蝇受精卵含母体磷酸化 蛋白 string,使1-13次卵 8 9 11 裂只发生细胞核的分裂, 15 无G期。其后,母体 string 蛋白消失,合子 string基 因按时空特异性表达,其 Fig14.3 Domains of mitosis in the表达受 gap、pair- ruled 等 Drosophila blastoderm. Mitotic domains基因产物的控制,只有表 that divide at the same time are indicated 达 string的细胞才能进入 有丝分裂。由于有丝分裂 by the various colors. The numbers ind-不同步,不同组织有不同 cate the order in which various regions 数量的细胞。 undergo mitosis at the 14th cycle. After Edgar, B.A., et al 1994
Developmental Biology 果蝇受精卵含母体磷酸化 蛋白string，使1－13次卵 裂只发生细胞核的分裂， 无G期。其后,母体string 蛋白消失，合子string基 因按时空特异性表达，其 表达受gap、pair-ruled等 基因产物的控制，只有表 达string的细胞才能进入 有丝分裂。由于有丝分裂 不同步，不同组织有不同 数量的细胞。 果蝇胚胎早期发育中细胞的分裂特点
Developmental Biology 人的生长速率因发育阶段而异 Average growth after birth Male and female comparative growth rates Height Change (cm)180 in height 10 (cm/year) Girls 24681012141618 89101112131415161718 Age(years) Age (years) Fig. 14.4 Normal human growth comparative growth rates of boys and Left panel: an average growth curve girls. There is a growth spurt at puberty for a human male after birth. Right panel: in both sexes, which occurs earlier in girls
Developmental Biology 人的生长速率因发育阶段而异
Developmental Biology 人躯体的不同部分有不同的生长速率 adult Weeks of development Age in years Fig 14.5 Different parts of the human body grow at relatively large but, with time, other parts of the body grow much different rates At 9 weeks of development, the head is more than the head. After Gray, H: 1995
Developmental Biology 人躯体的不同部分有不同的生长速率
Developmental Biology 营养对生长的影响 胚胎在子宫中发育期间营养不良,一般会产 生较小、但各部分比例正常的个体。 出生后营养不良可影响某些器官的正常生长。 如断奶后营养不良的大鼠骨架生长正常,但 肝和肾会很小。 出生时个体较小的婴儿,长大后易患心血管 疾病和非胰岛素依赖性糖尿病
Developmental Biology 营养对生长的影响 ➢胚胎在子宫中发育期间营养不良，一般会产 生较小、但各部分比例正常的个体。 ➢出生后营养不良可影响某些器官的正常生长。 如断奶后营养不良的大鼠骨架生长正常，但 肝和肾会很小。 ➢出生时个体较小的婴儿，长大后易患心血管 疾病和非胰岛素依赖性糖尿病
Developmental Biology 生长受激素的调控 Hypothalamus Fig 14.6 Growth hormone production is under the control of the hy pothal- Growth hormone releasing hormone <7 Somatostatin amic hormones. Growth hormone is made in the pituitary gland and is secreted 计f Growth hormone- releasing hormone from the hypothalamus promotes growth hormone synthesis, while somatostatin Pituitary inhibits it. growth hormone controls its Growth hormone own release by negative feedback signals to the hypothalamus. Growth hormone causes the synthesis of the insulin-like growth factor IGF-1 and this promotes the production of growth hormone IGF-1 synthesis 缺失IGF-2基因的小鼠出生时的重量 仅为正常鼠的60%,表明IGF2是早 期胚胎生长所必需的。IGF-1主要在 出生后起作用 Cell multiplication
Developmental Biology 生长受激素的调控 缺失IGF-2基因的小鼠出生时的重量 仅为正常鼠的60%，表明IGF-2是早 期胚胎生长所必需的。IGF-1主要在 出生后起作用
Developmental binlnov 不同的器官具有不同的内在生长程序 Length 9 Humerus Humerus H Ulna C-Humerus Wrist Scapula 0 357911131517 Phalanx I Time after initial formation(days) Radius Fig. 14.7 Comparative growth of the Humerus cartilaginous elements in the embryonic chick wing. When first laid down, the cartilaginous elements of the humerus carpus uIna and wrist are the same size, but the Metacarpus Ulna humerus and ulna then grow much more Figure 9-22 Formation of the skeleton in the mammalian forelimb than the wrist element
Developmental Biology 不同的器官具有不同的内在生长程序