Development of the diencephalon and the telencephalon. Development of the commissural pathways and the fornix

what do the diencephalon develop from?

the prosencephalon

what do the diencephalon consist of?

a roof plate and two alar plates

what do the roof plate of the diencephalon consist of?

single layer of ependymal cells covered by vascular mesenchyme

what will the layers of the roof plate of diencephalon give rise to?

choroid plexus of the 3rd ventricle

what will the most caudal part of the roof plate of diencephalon develop into?

pineal body

what will the alar plates of the diencephalon form?

lateral walls of the diencephalon

what divides the alar plates of diencephalon into a dorsal and ventral region?

hypothalamic sulcus

what will the dorsal region of the alar plate of the diencephalon give rise to?

thalamus

what will the ventra region of the alar plate of the diencephalon give rise to?

hypothalamus

what will the different parts of the hypothalamus give rise to?

different hypothalamic nuclei, incl. mammilary body

what do the anterior lobe of the pituitary gland develop from?

rathke’s pouch

what do the posterior lobe of the pituitary gland develop from?

infundibulum

what gives rise to the pituitary stalk. what do the pituitary stalk connect?

infundibulum

post. lobe of pituitary lobe to the hypothalamus

what do the telencephalon develop from?

prosencephalon

what do the prosencephalon consist of?

two lateral outpocketings and one median portion

what will the two lateral outpocketings of prosencephalon become?

cerebral hemispheres

what will the median portion of prosencephalon be?

lamina terminalis

when do the lateral outpocketings of the prosencephalon begin to extend?

in week 5

what happens in the regions where the cerebral hemispheres come in contact with the underlying diencephalon?

a single layer of ependymal cells form, covered by vascular mesenchyme

where do the hippocampus form?

form as a thickening of the hemispheres above the choroidal fissure

how are the gyri formed?

during final part of fetal life, the surface of the hemispheres grow so rapidly that the surface invaginates, forming the gyri

what do the cortex of the hemispheres develop from?

pallium

what is the pallium?

a layer of grey and white matter which covers the hemispheres

what are the different types of pallium?

paleopallium, archipallium and neopallium

sort the types of pallium by their phylogenic ages, starting with the eldest

paleopallium, archipallium and neopallium

how much of the cortex is neopallium?

90%

where can the paleopallium be found in humans?

floor of the hemispheres and comprises the rhinecephalon, a structure consisting of the olfactory bulb and surrounding structues

where is the archipallium located in humans?

medial surface of the hemispheres and comprises the hippocampus, indusium griseum and the fornix

which rapidly growing region forms while the hemispheres grow?

ganglion hill (striatal anlage)

what do the ganglion hill give rise to?

corpus striatum

describe the formation of the internal capsule

axons passing to and from cortex break through the corpus striatum

what do the internal capsule separate the striatum into?

caudate nucleus and lentiform nucleus

what do the lentiform nucleus consist of?

putamen and globus pallidus

describe the formation of the commissures

fibers grow between the hemispheres at the end of 3rd month

what are the commissures?

bundles of nerve fibers connecting the hemispheres

what is the first commissure to develop? what does it connect?

anterior commissure

connecting brain areas related to olfaction of one hemisphere to the other

what is the second commissure to develop? what does is connect?

hippocampal commissure / fornix

connect hippocampus of on hemisphere to the mamillary body and hypothalamus of the other

when do the corpus callosum appear? what does it connect?

by week 10

connects most of the cortexes of the two hemispheres with each other

what are some commissures that develop outside of the lamina terminalis?

posterior- and habenular-commissure as well as the optic chiasm