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