1. DIENCEPHALON
DEVELOPMENT

2. ANATOMY OF DIENCEPHALON
• CONSISTS OF THE THIRD VENTRICLE AND THE
STRUCTURES THAT FORM ITS BOUNDARIES
• EXTENT
• INTERVENTRICULAR FORAMEN--- ANTERIORLY
TO
• THE POINT WHERE THE 3rd VENTRICLE
BECOMES CONTINUOUS WITH THE
AQUEDUCT---POSTERIORLY

3. ANATOMY OF DIENCEPHLON
• INFERIOR SURFACE
• ONLY EXPOSED AREA
• INCLUDES FROM ANTERIOR TO POSTERIOR----
• OPTIC CHIASMA &OPTIC TRACT
• INFUNDIBULUM WITH TUBER CINEREUM
• MAMMILARY BODIES

4. ANATOMY OF DIENCEPHALON
• SUPRIOR SURFACE
• FORMED BY THE ROOF OF 3rd VENTRICLE
• CONCEALED BY FORNIX---A THICK BAND OF
FIBRES----ARISES IN THE HIPPOCAMPUS---
ARCHES OVER THE THALAMUS TO JOIN THE
MAMMILARY BODIES

5. ANATOMY OF DIENCEPHALON
• MEDIAL SURFACE
• FORMED BY—
• THALAMUS AND
• HYPOTHALAMUS
• LATERAL SURFACE
• BOUNDED BY
• INTERNAL CAPSULE

6. DEVELOPMENT OF DIENCEPHALON
• DEVELOPS FROM FOREBRAIN VESICLE
• ROOF AND FLOOR PLATES REMAIN THIN
• LATERAL WALLS BECOME THICK
• WITH THE CLOSURE OF THE ROSTRAL
NEUROPORE A DIVERTICULUM------THE
OPTIC VESICLE APPEARS ON EACH SIDE OF
THE FOREBRAIN
• PART OF BRAIN CAUDAL TO OPTIC VESICLE
FORMS THE DIENCEPHALON

8. DEVELOPMENT OF DIENCEPHALON
• RETINA AND OPTIC DISK DERIVED FROM
OPTIC VESICLE AND STALK
• CAVITY OF DIENCEPHALON FORMS THE
GREATER PART OF 3rd VENTRICLE
• SMALL PART OF THE CAVITY OF THE
TELENCEPHALON ALSO CONTRIBUTES TO THE
FORMATION OF 3rd VENTRICLE

9. DEVELOPMENT OF DIENCEPHALIN
• DIENCEPHALON CONSISTS OF---
• A ROOF PLATE AND
• TWO ALAR PLATES
• ROOF SHOWS A SMALL DIVERTICULUM
IMMEDIATELY ANTERIOR TO MIDBRAIN
WHICH WILL FORM THE PINEAL BODY
• REMAINDER OF THE ROOF WILL FORM THE
CHOROID PLEXUS OF 3rd VENTRICLE

10. DEVELOPMENT OF DIENCEPHALON
• THREE SWELLINGS DEVELOP IN THE LATERAL
WALL OF 3rd VENTRICLE WHICH LATER
BECOME THE---
• 1 EPITHALAMUS
• 2 THALAMUS
• 3 HYPOTHALAMUS

12. DEVELOPMENT OF DIENCEPHALON
• THALAMUS SEPARATED FROM EPITHALAMUS BY
EPITHALAMIC SULCUS
• THALAMUS SEPARATED FROM HYPOTHALAMUS
BY HYPOTHALAMIC SULCUS
• PINEAL BODY
• INITIALLY APPEARS AS AN EPITHELIAL
THICKENING IN MIDLINE
• BY 7th WEEK BEGINS TO EVAGINATE
• BECOMES A SOLID ORGAN ON THE ROOF OF
MESENCEPHALON

14. DEVELOPMENT OF DIENCEPHALON
• THALAMUS
• ARISES AS A THICKENING OF ALAR PLATE ON THE
LATERAL WALLS OF 3rd VENTRICLE
• DEVELOPS RAPIDLY ON EACH SIDE
• BULGES INTO THE CAVITY OF 3rd VENTRICLE
REDUCING IT TO A NARROW CLEFT
• IN 70 % OF BRAINS THE THALAMI MEET AND
FUSE IN THE MIDLINE FORMING A BRIDGE OF
GRAY MATER ACROSS THE 3rd VENTRICLE---THE
INTERTHALAMIC ADHESION OR MASSA
INTERMEDIA

16. DEVELOPMENT OF DIENCEPHALON
• MEDIAL GENICULATE BODY AND
• LATERAL GENICULATE BODY
• DEVELOP AS SOLID BUDS---- THE
METATHALAMUS

17. DEVELOPMENT OF DIENCEPHALON
• HYPOTHALAMUS
• ARISES BY PROLIFERATION OF NEUROBLASTS
IN LOWER PART OF ALAR PLATE ON EACH SIDE
OF 3rd VENTRICLE VENTRAL TO
HYPOTHALAMIC SULCUS
• A NUMBER OF NUCLEI CONCERNED WITH
ENDOCRINE ACTIVITIES AND HOMEOSTASIS
DEVELOP

18. DEVELOPMENT OF DIENCEPHALON
• MAMILLARY BODIES
• A PAIR OF NUCLEI
• FORM PEA-SIZED SWELLINGS ON THE
VENTRAL SURFACE OF HYPOTHALAMUS

19. DEVELOPMENT OF DIENCEPHALON
• THIRD VENTRICLE
• DEVELOPS FROM THE---
• 1 CAVITY OF DIENCEPHALON AND
• 2 SMALL PART OF THE CAVITY OF
TELENCEPHALON

20. DEVELOPMENT OF DIENCEPHALON
• THIRD VENTRICLE [ CONTD ]
• ROOF PLATE OF DIENCEPHALON IS THIN MADE
UP OF A SINGLE LAYER OF EPENDYMA
COVERED BY VASCULAR MESENCHYME
FORMING THE CHOROID PLEXUS
• ROOF EXTENDS FROM THE
INTERVENTRICULAR FORAMEN TO
HABENULAR COMMISSURE

22. DEVELOPMENT OF DIENCEPHALON
• THIRD VENTRICLE [ CONTD ]
• ANTERIOR WALL
• FORMED BY THE LAMINA TERMINALIS
• LATERAL WALL
• FORMED BY THE THALAMI
• FLOOR
• EXTENDS FROM OPTIC RECESS ON THE SUPERIOR
SURFACE OF OPTIC CHIASMA INTO THE
INFUNDIBULAR RECESS AND THEN ABOVE
MAMILLARY BODY TO THE AQUEDUCT

23. THANK YOU