Comparative Anatomy: P. Reyes, S. Campos, M. Rebanal, C.VJ. Gamil
Introduction to Comparative Anatomy
Studies the descriptive and functional morphology of vertebrates
● Descriptive - structure of vertebrates
● Functional - significance of the structure
Morphology - homologous and may be analogous to other animals/ structural evolution
Anatomy - description/use of structures, functions
In terms of structure, these are caudal fins, in terms of description, these are two kinds of caudal
fins
Significance of Comparative Anatomy
● To comprehend the structural basis of biology
● To probe the ancient past and study evolution
● To develop appreciation of vertebrates
● Lore,
● Lorem
Phylum Chordata
,Comparative Anatomy: P. Reyes, S. Campos, M. Rebanal, C.VJ. Gamil
- Two conventional classifications: vertebrates and invertebrates
- Group of small marine animals: protochordates (animals that exhibit
characteristics of vertebrate and invertebrates
- Closely related to echinodermata except they have notochords
5 distinct characteristics/structures (The Big 5)
- Are fundamental in the architecture of vertebrates
- No vertebrate will proceed without passing through the five characteristics in emcryonic
development
- Protochordates and chordates have been grouped in a single taxon
1. Postanal Tail
2. Dorsal hollow nerve cord (Spinal Cord)
3. Notochord
4. Pharynx
5. Endostyle
Notochord
- Rod of living cells ventral to
the central nervous system
and dorsal to the alimentary
canal
- Long tube cylinder of cartilage
- Provides skeletal support to
the length of the chordate
- In most vertebrates, it is more
complex, jointed skeleton
develops (vertebral column),
and the adult only retains
remnants of the embryonic
notochord (exists as disks in
between vertebral units)
a. Fate during development:
i. Head region - incorporated into the skull floor
ii. Trunk and tail - surrounded by cartilaginous or bony vertebrae
b. Fate in adulthood:
i. Protochordates - chief axial skeleton surrounded by notochord sheath (left
image)
, Comparative Anatomy: P. Reyes, S. Campos, M. Rebanal, C.VJ. Gamil
ii. Agnathans (jawless fishes) - similar to protochordates with addition of
lateral neural cartilages
iii. Fishes and amphibians - persist the length of the trunk and tail within
centrum
iv. Reptiles, birds and mammals - disappears and becomes pulpy nucleus in
mammal vertebrae
Figure 1 shows transverse section of the vertebral column. Figure 2 shows notocord of a lamprey
Vertebrae
- Provides more rigid support for the body compared
to the notochord
- Consists of:
a. Centrum: site where notochord is deposited
during early development
b. Neural arch: forms over the spinal cord
c. Various processes (spinous and transverse
processes)
Nerve Cord
- Develops from a plate of ectoderm that
rolls into a tube dorsal to the notochord
- Formed by invagination (cells undergo
different morphogenetic movement
during gastrulation)
- Nerve cord develops into the CNS
(brain and spinal cord)
Introduction to Comparative Anatomy
Studies the descriptive and functional morphology of vertebrates
● Descriptive - structure of vertebrates
● Functional - significance of the structure
Morphology - homologous and may be analogous to other animals/ structural evolution
Anatomy - description/use of structures, functions
In terms of structure, these are caudal fins, in terms of description, these are two kinds of caudal
fins
Significance of Comparative Anatomy
● To comprehend the structural basis of biology
● To probe the ancient past and study evolution
● To develop appreciation of vertebrates
● Lore,
● Lorem
Phylum Chordata
,Comparative Anatomy: P. Reyes, S. Campos, M. Rebanal, C.VJ. Gamil
- Two conventional classifications: vertebrates and invertebrates
- Group of small marine animals: protochordates (animals that exhibit
characteristics of vertebrate and invertebrates
- Closely related to echinodermata except they have notochords
5 distinct characteristics/structures (The Big 5)
- Are fundamental in the architecture of vertebrates
- No vertebrate will proceed without passing through the five characteristics in emcryonic
development
- Protochordates and chordates have been grouped in a single taxon
1. Postanal Tail
2. Dorsal hollow nerve cord (Spinal Cord)
3. Notochord
4. Pharynx
5. Endostyle
Notochord
- Rod of living cells ventral to
the central nervous system
and dorsal to the alimentary
canal
- Long tube cylinder of cartilage
- Provides skeletal support to
the length of the chordate
- In most vertebrates, it is more
complex, jointed skeleton
develops (vertebral column),
and the adult only retains
remnants of the embryonic
notochord (exists as disks in
between vertebral units)
a. Fate during development:
i. Head region - incorporated into the skull floor
ii. Trunk and tail - surrounded by cartilaginous or bony vertebrae
b. Fate in adulthood:
i. Protochordates - chief axial skeleton surrounded by notochord sheath (left
image)
, Comparative Anatomy: P. Reyes, S. Campos, M. Rebanal, C.VJ. Gamil
ii. Agnathans (jawless fishes) - similar to protochordates with addition of
lateral neural cartilages
iii. Fishes and amphibians - persist the length of the trunk and tail within
centrum
iv. Reptiles, birds and mammals - disappears and becomes pulpy nucleus in
mammal vertebrae
Figure 1 shows transverse section of the vertebral column. Figure 2 shows notocord of a lamprey
Vertebrae
- Provides more rigid support for the body compared
to the notochord
- Consists of:
a. Centrum: site where notochord is deposited
during early development
b. Neural arch: forms over the spinal cord
c. Various processes (spinous and transverse
processes)
Nerve Cord
- Develops from a plate of ectoderm that
rolls into a tube dorsal to the notochord
- Formed by invagination (cells undergo
different morphogenetic movement
during gastrulation)
- Nerve cord develops into the CNS
(brain and spinal cord)
