Comparative Anatomy
General Body Plan
Note Set 2
Chapters 2 & 4
Pharynx (fair-inks) with slits
Figure 3.1: Pharyngeal arches
(a) lateral view and
(b) ventral cross section.

Pharyngeal arches- associated with slits




Anamniotes (lower vertebrates)- have gill slits
Amniotes- have slits in embryo but gills never form
Endodermal pouches- pharyngeal pouch that grows toward
surface of animal
Ectodermal groove- pharyngeal groove on outside that
grows toward each pouch
Embryo
Figure 3.2: Embryo pharyngeal arches.
Figure 3.3: Embryo development at 1 month.
(a)


In tetrapods, 1st
pharyngeal slit
becomes auditory tube
and middle ear cavity
Aortic arches housed
by pharyngeal arch
(b)
Figure 3.4: Early pharyngeal devel.. of shark
(a) early stage (b) later stage.
Figure 3.5: Fate of
the pharyngeal
arches.




1st (mandibular) arch- mandibular and maxillary
portions
2nd (hyoid) arch
Other arches are numerically named
Most vertebrates have 6 pairs of arches
Figure 3.6: Pharyngeal arches.

Each pharyngeal arch contains a cartilage, artery,
mesoderm component, and cranial nerve.
Body Plan



Head
Trunk
Tail
Figure 3.7: Sagittal section of craniate embryo.
Head

Head


Cephalizationdevelopment of sense
organs
Protective covering of
dermal bone (not
replacement bone) or
cartilage
Figure 3.8.
Trunk


Somites- muscle masses
beside notochord;
embryonic structures
that turn into bone
Coelom- body cavity
between gut and body
wall, lined by peritoneum
Figure 3.10.
Figure 3.9:
Coelom.
Trunk (cont.)

Other visceral organ
cavities:



Heart- pericardium
Lungs- pleura
Abdomen- peritoneum
Figure 3.12: Pericardium and pleural cavities.
Figure 3.11:
Pericardium
cavities.
Tail

From body to end of the digestive tract
Somites and notochord
 Innervations
 Dorsal and ventral aorta
 Food storage, defense, locomotion

Pituitary Development
Figure 3.13


Stomodeal ectoderm plate
pushes inward and forms
pocket (Rathke’s pouch) that
leads to anterior lobe
This invagination meets the
dienchephalon’s infundibular
process which forms the
posterior lobe
Figure 3.14
Characteristics of Vertebrates



Divided into two superclasses: Pisces and
Tetrapoda
Demonstrate bilateral symmetry
Distinguishing features of vertebrates:
Presence of notochord
 Pharynx with slits
 Dorsal tubular nervous system
 Developed vertebrae
 Post anal tail

Notochord

Most primitive endoskeletal structure
Jawless fish- n.c. long and enlarged
 Cartilagenous fish- n.c. surrounded by cartilagenous
vertebrae
 Bony fish and amphibians- n.c. surrounded by larger
vertebrae
 Amniotes- n.c. almost lost

Notochord (cont.)


In mammals,
between successive
centrum are disks
Within disks, the
notochord is mostly
replaced with pulpy
nucleus
Figure 3.15: Vertebrae.
Figure 3.16: MRI
scan of notochord.
More Vertebrate Features

Dorsal Nervous System
CNS- brain and spinal cord
 Anamniotes- 10 pairs of cranial nerves
 Amniotes- 12 pairs of cranial nerves


Vertebrae column


Backbones
Post-anal tail
Figure 3.17: Vertebral column.
Anatomical Directions
Figure 3.18.
Figure 3.19.
Cranial Nerves
Olfactory
 Optic
 Oculomotor
 Trochlear
 Trigeminal
 Abducens
 Facial
 Vestibulocochlear
 Glossopharyngeal
 Vagus
Amniotes only:
 Spinal Accessory
 Hypoglossal

Figure 3.20
Literature Cited
Figure 3.1- http://www.nature.com/nrg/journal/v2/n11/images/nrg1101-858a-i1.gif
Figure 3.2- http://www.ratbehavior.org/images/EmbryoPharyngealArches.jpg
Figure 3.3- http://islam.org.hk/It_is_the_Truth/somites.htm
Figure 3.4, 3.7, 3.8, 3.10, & 3.18- Kent, George C. and Robert K. Carr. Comparative
Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
Figure 3.5- http://pharyngula.org/images/arch_fates.gif
Figure 3.6- http://connection.lww.com/Products/sadler/imagebank.asp
Figure 3.9- http://www.sci.nu.ac.th/biology/elearning/picture5/7_coelomate.jpg
Figure 3.11- http://mywebpages.comcast.net/wnor/thoraxlesson4.htm
Figure 3.12- http://faculty.southwest.tn.edu/rburkett/A&P%20body%20cavities.htm
Figure 3.13- http://people.musc.edu/~wilburd/Head%20and%20Neck%20I/sld012.htm
Figure 3.14- http://www.cushings-help.com/rathke.htm
Figure 3.15- http://cal.vet.upenn.edu/saortho/chapter_62/62mast.htm
Figure 3.16- http://www.telepathology.com/cases/forum/case17g.jpg
Figure 3.17- http://anthro.palomar.edu/primate/footnote.htm
Figure 3.19http://encyclopedia.thefreedictionary.com/Terms%20for%20anatomical%20location
Figure 3.20http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.html