| BRAIN OF CALOTES (GARDEN LIZARD) | BRAIN OF COLUMBA (PIGEON) | BRAIN OF ORYCTOLAGUS (RABBIT) | ||
| 1. Brain of lizard is relatively small and simple in proportion to the body. | 1. Avian brain is much more developed. | 1. Mammalian brain is very large and is most advanced in the animal kingdom. | ||
| 2. Brain is protected by two meninges. They are outer thick duramater and inner thin piamater. | 2. Same as in calotes. | 2. Brain is protected three meninges. They are outer thick dura mater, inner thin pia mater and archanoid membrane in between the two meninges. | ||
| PROSEN-CEPHALON | ||||
| 3. Olfactory lobes are large diferentiated into an olfactory tract or peduncle and olfactory bulb. | 3. The o¥actory lobes are very small and greatly covered by the cerebral hemispheres. | 3. Olfactory lobes are more distinctly visible on the ventral side of the cerebral hemispheres. | ||
| 4. There is no tuber culum of olfactorium. Olfactory lobes are enclosed by olfactory ventricle. | 4. There are no tube-rculum of olfactorium and olfactory ventricle | 4. Each lobe has olfactory peduncle & olfactory bulb. The peduncle ends behind in a slightly renewed elevation the tuberculum of olfactorium. | ||
| 5. Cerebral hemispheres are oval with narrow antero posterior ends. These are medially separated by a mid-dorsal fissure. | 5. Cerebral hemispheres are very large and form about half of the brain. | 5. Cerebral hemispheres are triangular in shape and very large and form about half of the brain. | ||
| 6. Cerebral hemispheres do not cover olfactory and optic lobes but partly overlap the diencephalon. | 6. Cerebral hemispheres largely cover olfactory bbes and diencephalon. These do not overlap optic lobes. | 6. Cerebral hemispheres largely cover olfactory lobes diencephalon & optic lobes. | ||
| 7. There is no corpus callosum. | 7. There is no corpus callosum. | 7. Cerebral hemispheres are and connected with other by a horizontal transverse band-corpus callosum. | ||
| 8. Fornix is absent. | 8. Fornix is absent. | 8. Posterior end of corpus callosum bends down and extends forward as fornix. | ||
| 9. The surface of cerebral hemispheres is smooth and are not differentiated, into lobes. | 9. The surface of cerebral hemispheres is smooth and are not differentiated into lobes. | 9. Each cerebral hemisphere is differentiated into four lobes - Frontal, parietal, Temporal & Hippo campal. | ||
| 10. Cerebral cortex is not well developed. | 10. Same as in calotes. | 10. Cerebral cortex is well developed. | ||
| 11. Corpora striata are quite conspicuous. | 11. Corpora striata are very conspicuous. | 11. Corpora striata are less conspicuous | ||
| 12. Lateral ventricles are unbranched. | 12. Same as in calotes. | 12. Lateral ventricles are branched. | ||
| 13. Diencephalon is a small rounded area pressed between the cerebrum and midbrain. | 13. Diencephalon is visible on the ventral side and dorsally cov-ered by cerebral hemispheres. | 13. Diencephalon is comparatively small and -completely covered with backward extension of cerebral hemispheres. | ||
| 14. Diencephelon roof is thin and forms anterior choroid plexus. | 14. Same as in calotes. | 14. The roof of dienceph-alon is thin and highly vascular and forms the anterior choroid plexus. | ||
| 15. Epiphysial apparatus possess an anterior parietal body and posterior penial body. | 15. Epiphysial apparatus possess pineal body as. | 15. Same as in columba. | ||
| 16. Optic thalami are present but middle commissure is lacking. | 16. Opticthalamiare well developed but there is no middle commissure. | 16. Opticthalami are connected together by a thick band of grey matter called as middle commissure. | ||
| 17. Pineal eye is present. | 17. Absent. | 17. Absent. | ||
| 18. Corpus albicans is absent. | 18. Absent. | 18. Asmall, rounded body, the corpus albicans or corpus mamillare present behind pituitary body. | ||
| MESEN-CEPHALON | ||||
| 19. Two optic lobes are oval and are present dorsally to form corpora bigemina | 19. Two optic are large and present laterally to form corpora bigemina. | 19. Optic lobes are small and four in number and form as corpora quadri gemina which are covered by cerebellum. | ||
| 20. The crura cerebri at the floor of midbrain are poorly developed. | 20. Crura cerebri are well developed. | 20. Crura cerebri are highly developed. | ||
| 21. Optic lobes are hollow with optocoels. | 21. Optocoels are much reduced. | 21. Optic lobes are solid and without optocoels. | ||
| RHOMBEN-CEPHALON | ||||
| 22. Cerebellum is poorly developed and it is in the form of a flattened ridge at the anterior end of medulla oblongata. | 22. Cerebellum is comparatively more developed and divided into two lateral and a median lobe. | 22. Cerebellum is very well developed and divided into two lateral lobes and a median lobe. | ||
| 23. Cerebellum surface is smooth. | 23. Cerebellum surface is folded all over. | 23. Same as in bird. | ||
| 24. Cerebellum is not differentiated into lobes. | 24. Cerebellum is differentiated into three lobes - a median large, oval central lobe or vermis and pair of very small lateral floccular lobes. | 24. Cerebellum is differentiated into five lobes - a median large central lobe or vermis, a pair of smaller lateral lobes and a pair of still smaller floccular lobes. | ||
| 25. Pons varolii are absent. | 25. Same as in calotes. | 25. Pons varolii are present and connect the lateral parts of the cerebellum. | ||
| 26. There is no arbor vitae. | 26. Same as in calotes. | 26, White matter forms tree-like arbor vitae in grey matter can be seen in the section of cerebellum. | ||
| 27. Medulla oblongata is not overlapped by the cerebellum. | 27. Medulla oblongata is overhung by cerebellum. | 27. Same as in cloumba. | ||
| 28. It has a distinct ventral flexure. | 28. Same as in calotes. | 28. Ventral flexure is absent. | ||
| 29. Ventral fissure and ventral pyramids are absent. | 29. Same as in calotes. | 29. There is a median ventral fissure bordered by two narrow bands - the ventral pyramids. | ||
| 30. Corpora trapezo-idea are not formed. | 30. Corporatrapezoidea are lacking. | 30. A pair of oblong patches - corpora trape-zoidea are present just behind pons varolii. | ||
| 31. The roof of medulla is thin and vascular which forms the posterior choroid plexus | 31. The posterior choroid plexus is completely covered with the cerebellum. | 31. The roof of medulla is exceptionally thin and forms the posterior choroid plexus. | ||
| 32. Velum medullae anterius is not formed. | 32. Velum medullae i; absent. | 32. A thin transparent membrane - Velum medullae anterius forms the roof over the anterior part of the fourth ventricle. This connects the optic lobes with the cerebellum. | ||
| 33. Velum medullae posterius is absent. | 33. Same as in calotes | 33. A thin transparent membrane - Velum medullae posterius forms the roof over hind part of the fourth ventricle. |
