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Sectioning, Dissection and
Skeletal Elements
Sections
1-vertical sections 2-Transverse sections
V.S. of skin
1- Ascidia.2- Branchiostoma.
3- Petromyzon.4- Carchrinus.5- Chalcides.
T.S. of pharyngeal, trunk & tailregions.
1- L.S. of Ascidia.2- Branchiostoma.
3- Ammocoete larva.4- Carchrinus. 5- Oreochromis.6- Chalcides.
protochordates
vertebrates
protochordates
vertebrates
V.S. of skin
Epidermis
Single layer stratified
epidermis
epidermis
protochordates vertebrates
Epidermis consists of a single layer
Skin is covered with a thick testcontaining vascular ampullae Epidermis contains golblet cells
Ascidia Branchiostoma
test
epidermis
Goblet cell
epidermis
Stratified epidermis
Epidermis contains Club-shaped cells
Skin containsPlacoid scales
Skin is covered withhorny scales
PetromyzonCarcharinus Chalcides
Horny scalePlacoid scaleClub-shaped cell
sections
Notochord
absent Well developed Replaced by centra of vertebrae
L.S. ofAscidia
Consists ofMuscular plates
Branchiostoma
Consists ofVacuolated cells
Ammocoete larva
myotomes
ConcentricallyArranged muscle
lamellae
Carcharinus
Small muscle fibers
Skin Contains Cycloid scales
Skin is Covered withHorny scales
Oreochromis Chalcides
I-The notochord is entirely absent.
-The animal is surrounded with a thick test.
L.S. of Ascidia.
test
II- The notochord is well developed & surrouded by a fibrous sheath.
A-The notochord consists of muscular plates.
-The myosepta of one side alternate with those of the other side.
…….Sections in Branchiostoma….. (2)
myoseptum
notochord
Nerve cord
myotome
Fibrous
sheath
Muscle plates
B- The notochord consists of vacuolated cells and surrounded by a fibrous sheath.
- both myotomes and myosepta are dorso-ventrally directed.
……….Sections in ammocoete larva… (3).
Nerve cord
notochord
myotome
myoseptum
III-The large part of the notochord is replaced by centra of vertebrae.
……. Sections in Carcharinus, Oreochromis and Chalcides (A, B &C).
neural arch
nerve cord
centrum
Remnant of
notochord
Skeleton of pigeon
Skeletal system of rabbit
Cervical vertebrae
-Atlas & axis possess vertebrarterial foramens.
a-Atlas contains 2 condylar facets anteriorly &
two facets for axis posteriorly.
Vert. foramen
Facet for axis
Condylar
facet
b--Axis is characterized by
1-odontoid process anteriorly.
Odontoid process
2- postzygapophysis posteriorly.
postzygapophysis
The normal cervical vertebra is characterized by
1-anterior and posterior zygapophyses.
2-Vertebarterial foramen.
postzygapophysis
prezygapophysis
Vertebarterial
foramen
Neural spine
It is charaterized by:
1-long spine.
2-pre & postzygapophyses.
postzygapophysis
prezygapophysis
Lumbar is
characterized by:
1-long transverse
processes.
2-metapophyses.
3-Pre and
postzygapophyses.
Sacral vertebra is characterized by:
1-Broad transverse processes.
2-Pre and postzygapophyses.
Girdles
-with dorsal spine.
-with a glenoid cavity.
Dorsal spine
Glenoid
cavity
-With ilium and ischium bones.
- Contains acetabulum.
Dissection 1-Oreochromis:
2-Dissection of Chalcides
3-Dissection of rabbit
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