间脑-大脑的发生

1、眼的发生眼的发生 a | The neural plate is the starting point for the development of the vertebrate eye cup. b | The neural plate folds upwards and inwards. c | The optic grooves evaginate. d | The lips of the neural folds approach each other and the optic vesicles bulge outwards. e | After the lips have seal

2、ed the neural tube is pinched off. At this stage the forebrain grows upwards and the optic vesicles continue to balloon outwards: they contact the surface ectoderm and induce the lens placode. f | The optic vesicle now invaginates, so that the future retina is apposed to the future retinal pigment e

3、pithelium (RPE), and the ventricular space that was between them disappears. Developing retinal ganglion cells send axons out across the retinal surface. The surface ectoderm at the lens placode begins to form the lens pit. This section is midline in the right eye, through the choroid fissure, so on

4、ly the upper region of the retina and the RPE are visible. g | The eye cup grows circumferentially, eventually sealing over the choroidal fissure and enclosing the axons of the optic nerve (as well as the hyaloid/retinal vessels; not shown). The ectodermal tissue continues to differentiate and event

5、ually forms the lens.In the embryo, as in the adult, the roof of the diencephalon is very thin comprised only of ependyma plus adjacent pia called the tela choroidea. When blood vessels invade the tela choroidea, the choroid plexus of the 3rd ventricle, fourth ventricle, and lateral ventricles devel

6、op. The thin medial wall of the ventricle is the choroid fissure; its most rostral point is at the interventricular foramen. In the adult the choroid fissure is C- shaped and continuous in the medial walls of the parietal and temporal lobes. Early in development, the diencephalon develops 2 pairs of

7、 prominent swellings in the walls of the 3rd ventricle. The swellings represent only the alar plate; there is no basal plate. The largest mass is the thalamus dorsally, separated by the hypothalamus and hypothalamic sulcus. Where the roof plate thickens along the medial wall of the thalamus are the

8、smaller swellings of the epithalamus comprised of the a) midline pineal gland, b) paired habenular nuclei, and c) paired stria medullaries.The corpus striatum is comprised of two structures a) caudate-putamen and b) globus pallidus. In the adult the caudate and putamen are partially separated by fib

9、ers of the anterior limb of the internal capsule. The posterior limb of the internal capsule separates the globus pallidus from the diencephalon (thalamus).Early in the development of the cerebral vesicles. The caudate-putamen develops from neuroblasts of the floor of the developing telencephalic ve

10、sicle called the striatal ridge while the globus pallidus originates from neuroblasts in the wall of the 3rd ventricle of the diencephalon. Pallidal neuroblasts eventually migrate laterally to join the caudate-putamen. Both parts of the corpus striatum originate near the foramen of Monro. At first,

11、during the caudal expansion of the telencephalic vesicles, the hemispheres are separate from the diencephalon (except at the foramen of Monro). Later, when the hemispheres begin their complex bending, the medial aspects of the growing hemispheres approach the diencephalon and their apposing surfaces

12、 fuse. After the fusion, corticofugal fibers (internal capsule) heading to and from the cerebral cortex incompletely divides the caudate nucleus from the putamen. The globus pallidus remains in the inner wall of the diencephalon. Later, then putamen merges with the globus pallidus forming the lentic

13、ular nucleus. As the hemisphere grows backward, the body of the caudate nucleus portion of the striatal ridge in the floor of the lateral ventricle follows the wall of the developing lateral ventricle downward into the roof of the inferior horn of the lateral ventricle where it forms the tail of the

14、 caudate nucleus. Adenohypohysis:Pars distalis - the largest section Pars tuberalis - a collar of tissue that usually surrounds the infundibular stalk Pars intermedia - a narrow band that is usually separated from the pars distalis by a hypophyseal cleft Neurohypohysis:Pars nervosa - the bulk of the

15、 posterior pituitary Median emminence - the upper section of the neurohypophysis above the pars tuberalis Infundibular stalk - the stem that connects the pars nervosa to the base of the brain 脑垂体的发生脑垂体的发生外形的发生皮质的发生髓质的发生Posteriolateral growth of the cerebral hemispheres encloses the diencephalon and

16、superior aspect of the brain stem Early in the development e.g., 12 weeks of the cerebral hemispheres, the surface is smooth without sulci. The various lobes of the brain are present. By about 7 months rapid growth of the hemispheres results in the development of gyri and sulci. At birth, the main g

17、yri and sulci of adult brain are recognized. (1) First to appear is paleocortex (palleopallium)(2) Next is archicortex (archipallium)(3) Latest to appear is neocortex (neopallium) na | Schematic diagram of a section through the developing rodent forebrain. b,c | Illustrations of the different stages

18、 of neocortical development. The dorsal forebrain gives rise to the cerebral cortex. The lateral ganglionic eminence (LGE) and medial ganglionic eminence (MGE) of the ventral forebrain generate the neurons of the basal ganglia and the cortical interneurons; the latter follow tangential migratory rou

19、tes to the cortex (a; arrows). In the dorsal forebrain (a; boxed area), neuronal migration begins when the first cohort of postmitotic neurons moves out of the ventricular zone (VZ) to form the preplate (PP) (b). Subsequent cohorts of neurons (pyramidal cells) migrate, aided by radial glia, through

20、the intermediate zone (IZ) to split the PP into the outer marginal zone (MZ) and inner subplate (SP) (c). CP, cortical plate. - Inside-out development of the cortex - the first cells to migrate to cortical plate from VZ that form subplate - As these differentiate into neurons become layer VI in the

21、cortical plate. - this process repeats again and again until all layers of the cortex the sublate neurons disappear 较早分化的较大神经元先迁移并形成最内层，依次顺序向外；而较晚分化的较小神经元则通较早分化的较大神经元先迁移并形成最内层，依次顺序向外；而较晚分化的较小神经元则通过已形成的层次迁移并形成其外侧新的层次；过已形成的层次迁移并形成其外侧新的层次；故不论皮质的什么区域，其最内层总是最早分故不论皮质的什么区域，其最内层总是最早分化，而最外层则最后分化。化，而最外层则最后分化。

22、A | The Boulder Committees original summary diagram of neocortical development. B | Our revised version. Comparison of these two illustrations summarizes our redefinition of the sequence of events and the formation of transient compartments, including the preplate (PP) and the intermediate and subpl

23、ate zones (IZ and SP). The panels in part B correspond to the following approximate ages (for the lateral part of the dorsal telencephalon): a: embryonic day (E) 30; b: E31E32; c: E45; d: E55; e: gestational week 14. CP, cortical plate; I & IZ, intermediate zone; M & MZ, marginal zone; S &am

24、p; SVZ, subventricular zone; (SG), subpial granular layer (part of the MZ); V & VZ, ventricular zone. Part A reproduced, with permission, from ref. 4 (1970) Wiley The lamina terminalis is the most rostral structure of the early telencephalon. By 10 weeks it contains the rudiments of the commissu

25、ral bundles i.e., corpus callosum, commissure of the fornix, optic chiasm and anterior commissure. The midline lamina terminalis provides the only location where nerves interconnect the two cerebral hemispheres. Crossing fibers of the optic chiasm develop in the lamina ventrally, the anterior commis

26、sure connects olfactory bulbs and temporal lobes, the commissure of the fornix joins the hippocampal formations, and most dorsally is the corpus callosum which connects non-olfactory cortical areas. Other crossing fibers do not connect the hemispheres e.g., the posterior commissure connects preoptic areas and the habenular commissure connects habenular nuclei.Just behind the lamina terminalis is the interventricular foramina (of Monro), which connects the 3rd ventricle with the lateral ventricles of the developing hemispheres. T