间脑-大脑的发生

1、眼的发生眼的发生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 develop. The thin

2、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 prominent sw

3、ellings 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 smaller swell

4、ings 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 fibers of the an

5、terior 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 vesicle called

6、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, during the ca

7、udal 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 fuse. After

8、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 lenticular nucleus.

9、 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 caudate nucl

10、eus. 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 posterior pi

11、tuitary 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 superior aspe

12、ct 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 gyri and sulci

13、 of adult brain are recognized. (1) First to appear is paleocortex (palleopallium)(2) Next is archicortex (archipallium)(3) Latest to appear is neocortex (neopallium) - Inside-out development of the cortex - the first cells to migrate to cortical plate from VZ that form subplate - As these different

14、iate into neurons become layer VI in the 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

15、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。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 pre

16、plate (PP) and the intermediate and subplate 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, intermedia

17、te zone; M & MZ, marginal zone; S & 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

18、it contains the rudiments of the commissural 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

19、the lamina ventrally, the anterior commissure 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., t

20、he 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. The lamina terminalis represents the membrane formed at the point of closure of the anterior neuropore. The stria medullaris and tela choroidea form the roof of the 3rd ventricle. Development of Corpus call