5 ROOF PLATE & EPIPHYSIS Roof plate Choroid plexus of 3rd ventricle Most caudal part of roof plate develops into epiphysis/ pineal body
6 Pineal bodyAppears as epithelial thickening in the midline, but by 7th week it begins to evaginateEventually it becomes a solid organ on the roof of mesencephalonFunction: Respond to light and darkness & affect the endocrine and behavioral rhythmsIn adults calcium is frequently deposited in the epiphysis and then serve as land marks on radiographs of skull.
8 ALAR PLATES Forms lateral wall of diencephalon A groove hypothalamic sulcus divides it into:ThalamusHypothalamus
9 THALAMUSThalamus gradually projects into the lumen of diencephalon due to proliferation of cellsFrequently the expansion is so great that two thalami fuse in mid line forming massa Intermedia or Interthalamic connexus
10 HYPOTHALMUS Forms the lower portions of alar plate Differentiate into number of nuclear masses that regulate visceral functionsMammillary body forms a distinct protuberance on the ventral surface of hypothalamus on each side of midline
12 Hypophysis/Pituitary Gland-Ectodermal Develops from two sources:An ectodermal outpocketing of the stomodeum---- Rathke’s pouchDownward extension of diencephalon---- the infundibulum
13 Cont…At 3 weeks Rathke’s pouch appear as evagination that grows dorsally towards infundibulum.By the end of 2nd month it loses its connection with the oral cavityComes to lie in close contact with infundibulum
15 Cont…Cells in the anterior wall rapidly proliferate and form the ---- anterior lobe/ adenohypophsis.A small extension of the lobe is pars tuberalis that surrounds the infundibulumThe posterior wall of pouch forms the --- pars IntermediaInfundibulum give rise to stalk & pars nervosa----posterior lobe/Neurohypophysis
17 HYPOPHYSEAL DEFECTS CRANIOPHARYNGIOMAS Remnant of Rathke’s pouch
18 Cerebral HemispheresArise by 5th week as bilateral evaginations of lateral wall of forebrainInterventricular foramen
19 CEREBRAL HEMISPHERESMiddle of 2nd month the basal part/floor of hemispheres begins to grow & bulges into lumen of lateral ventricle & into floor of foramen of MonroIn T.S this rapidly growing region has striated appearance therefore called Corpus striatumC.H become C-shapedChoroid plexus develop in the region where wall of hemisphere is attached to roof of diencephalon
20 CORPUS STRIATUMAs the cerebral cortex differentiates the axons passing to & from the cortex (Internal capsule) break the nuclear masses into:dorsomedial portion caudate nucleusventrolateral portion the lentiform nucleusMedial wall of C.H fuse with lateral wall of diencephalon
21 CHOROID FISSUREThe Lateral ventricle become C-shaped due to growth & curvature of C.HThe caudal end of each C.H turns ventrally & then rostrally, forming the temporal lobe & in so doing it carries the ventricle (forming temporal horn) & Choroid fissure with it.
22 CHOROID PLEXUSChoroid plexus protrude in the lateral ventricle along the choroid fissureThe thin medial wall of the C.H is invaginated along the choroid fissure by vascular pia matter to form choroid plexus of temporal horn
24 Growth of cerebral hemispheres C.H grow in anterior, posterior & inferior directions resulting in formation of frontal, occipital & temporal lobes.As growth in the region of corpus striatum slows the region b/w frontal & temporal lobes depressed & is called insulaThis region is later overgrown by other lobes Which completely covers it at birth.