Comparative Comparative AnatomyAnatomy

General Body PlanGeneral Body Plan

Note Set 2Note Set 2

Chapters 2 Chapters 2 & 4 & 4

Pharynx Pharynx (fair-inks)(fair-inks) with slits with slits

Pharyngeal archesPharyngeal arches- associated with slits- associated with slits Anamniotes (lower vertebrates)- have gill slitsAnamniotes (lower vertebrates)- have gill slits Amniotes- have slits in embryo but gills Amniotes- have slits in embryo but gills nevernever form form

Endodermal pouchesEndodermal pouches- pharyngeal pouch that grows toward - pharyngeal pouch that grows toward surface of animalsurface of animal

Ectodermal grooveEctodermal groove- pharyngeal groove on outside that grows - pharyngeal groove on outside that grows toward each pouchtoward each pouch

Figure 3.1: Pharyngeal arches

(a) lateral view and (b) ventral cross

section.

EmbryoEmbryo

Figure 3.2: Embryo pharyngeal arches.Figure 3.3: Embryo development at 1 month.

In tetrapods, 1In tetrapods, 1stst pharyngeal slit pharyngeal slit becomes auditory becomes auditory tube and middle tube and middle ear cavityear cavity

Aortic arches Aortic arches housed by housed by pharyngeal archpharyngeal arch

Figure 3.4: Early pharyngeal devel.. of shark (a) early stage (b) later stage.

(a)

(b)

11stst (mandibular) arch- mandibular and maxillary portions (mandibular) arch- mandibular and maxillary portions 22ndnd (hyoid) arch (hyoid) arch Other arches are numerically namedOther arches are numerically named Most vertebrates have 6 pairs of archesMost vertebrates have 6 pairs of arches

Figure 3.5: Fate of the pharyngeal arches.

Each pharyngeal arch contains a Each pharyngeal arch contains a cartilage, artery, mesoderm cartilage, artery, mesoderm component, and cranial nerve.component, and cranial nerve.

Figure 3.6: Pharyngeal arches.

Body PlanBody Plan

HeadHead TrunkTrunk TailTail

Figure 3.7: Sagittal section of craniate embryo.

HeadHead

HeadHead CephalizationCephalization- -

development of development of sense organssense organs

Protective covering Protective covering of dermal bone (not of dermal bone (not replacement bone) replacement bone) or cartilageor cartilage

Figure 3.8.

TrunkTrunk Somites- muscle Somites- muscle

masses beside masses beside notochord; embryonic notochord; embryonic structures that turn structures that turn into boneinto bone

Coelom- body cavity Coelom- body cavity between gut and body between gut and body wall, lined by wall, lined by peritoneumperitoneum

Figure 3.9: Coelom.

Figure 3.10.

Trunk Trunk (cont.)(cont.)

Other visceral Other visceral organ cavities:organ cavities: Heart- pericardiumHeart- pericardium Lungs- pleuraLungs- pleura Abdomen- Abdomen-

peritoneumperitoneum

Figure 3.11: Pericardium cavities.

Figure 3.12: Pericardium and pleural cavities.

TailTail

From body to end of the digestive From body to end of the digestive tracttract Somites and notochordSomites and notochord InnervationsInnervations Dorsal and ventral aortaDorsal and ventral aorta Food storage, defense, locomotionFood storage, defense, locomotion

Pituitary DevelopmentPituitary Development

Stomodeal ectoderm Stomodeal ectoderm plate pushes inward and plate pushes inward and forms pocket (Rathke’s forms pocket (Rathke’s pouch) that leads to pouch) that leads to anterior lobeanterior lobe

This invagination meets This invagination meets the dienchephalon’s the dienchephalon’s infundibular process infundibular process which forms the which forms the posterior lobeposterior lobe

Figure 3.13

Figure 3.14

Characteristics of Characteristics of VertebratesVertebrates

Divided into two superclasses: Pisces Divided into two superclasses: Pisces and Tetrapodaand Tetrapoda

Demonstrate bilateral symmetryDemonstrate bilateral symmetry Distinguishing features of vertebrates:Distinguishing features of vertebrates:

Presence of notochordPresence of notochord Pharynx with slitsPharynx with slits Dorsal tubular nervous systemDorsal tubular nervous system Developed vertebraeDeveloped vertebrae Post anal tailPost anal tail

NotochordNotochord

Most primitive endoskeletal Most primitive endoskeletal structurestructure Jawless fish- n.c. long and enlargedJawless fish- n.c. long and enlarged Cartilagenous fish- n.c. surrounded by Cartilagenous fish- n.c. surrounded by

cartilagenous vertebraecartilagenous vertebrae Bony fish and amphibians- n.c. Bony fish and amphibians- n.c.

surrounded by larger vertebraesurrounded by larger vertebrae Amniotes- n.c. almost lostAmniotes- n.c. almost lost

Notochord Notochord (cont.)(cont.)

In mammals, In mammals, between between successive successive centrum are centrum are disksdisks

Within disks, Within disks, the notochord the notochord is mostly is mostly replaced with replaced with pulpy nucleuspulpy nucleus

Figure 3.15: Vertebrae.

Figure 3.16: MRI scan of notochord.

More Vertebrate More Vertebrate FeaturesFeatures

Dorsal Nervous SystemDorsal Nervous System CNS- brain and spinal cordCNS- brain and spinal cord Anamniotes- 10 pairs of cranial nervesAnamniotes- 10 pairs of cranial nerves Amniotes- 12 pairs of cranial nervesAmniotes- 12 pairs of cranial nerves

Vertebrae columnVertebrae column BackboneBackboness

Post-anal tailPost-anal tail

Figure 3.17: Vertebral column.

Anatomical DirectionsAnatomical Directions

Figure 3.18.

Figure 3.19.

Cranial NervesCranial Nerves OlfactoryOlfactory OpticOptic OculomotorOculomotor TrochlearTrochlear TrigeminalTrigeminal AbducensAbducens FacialFacial VestibulocochleVestibulocochle

arar GlossopharyngeGlossopharynge

alal VagusVagusAmniotes onlyAmniotes only:: Spinal Spinal

AccessoryAccessory HypoglossalHypoglossal

Figure 3.20

Literature CitedLiterature CitedFigure 3.1- http://www.nature.com/nrg/journal/v2/n11/images/nrg1101-858a-Figure 3.1- http://www.nature.com/nrg/journal/v2/n11/images/nrg1101-858a-

i1.gifi1.gifFigure 3.2- http://www.ratbehavior.org/images/EmbryoPharyngealArches.jpgFigure 3.2- http://www.ratbehavior.org/images/EmbryoPharyngealArches.jpgFigure 3.3- http://islam.org.hk/It_is_the_Truth/somites.htmFigure 3.3- http://islam.org.hk/It_is_the_Truth/somites.htmFigure 3.4, 3.7, 3.8, 3.10, & 3.18- Kent, George C. and Robert K. Carr. 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.Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.Figure 3.5- http://pharyngula.org/images/arch_fates.gif Figure 3.5- http://pharyngula.org/images/arch_fates.gif Figure 3.6- http://connection.lww.com/Products/sadler/imagebank.asp Figure 3.6- http://connection.lww.com/Products/sadler/imagebank.asp Figure 3.9- Figure 3.9-

http://www.sci.nu.ac.th/biology/elearning/picture5/7_coelomate.jpghttp://www.sci.nu.ac.th/biology/elearning/picture5/7_coelomate.jpgFigure 3.11- http://mywebpages.comcast.net/wnor/thoraxlesson4.htmFigure 3.11- http://mywebpages.comcast.net/wnor/thoraxlesson4.htmFigure 3.12- http://faculty.southwest.tn.edu/rburkett/A&P%20bodyFigure 3.12- http://faculty.southwest.tn.edu/rburkett/A&P%20body

%20cavities.htm%20cavities.htmFigure 3.13- Figure 3.13-

http://people.musc.edu/~wilburd/Head%20and%20Neck%20I/sld012.htmhttp://people.musc.edu/~wilburd/Head%20and%20Neck%20I/sld012.htmFigure 3.14- http://www.cushings-help.com/rathke.htmFigure 3.14- http://www.cushings-help.com/rathke.htmFigure 3.15- http://cal.vet.upenn.edu/saortho/chapter_62/62mast.htm Figure 3.15- http://cal.vet.upenn.edu/saortho/chapter_62/62mast.htm Figure 3.16- http://www.telepathology.com/cases/forum/case17g.jpgFigure 3.16- http://www.telepathology.com/cases/forum/case17g.jpgFigure 3.17- http://anthro.palomar.edu/primate/footnote.htmFigure 3.17- http://anthro.palomar.edu/primate/footnote.htmFigure 3.19- http://encyclopedia.thefreedictionary.com/Terms%20forFigure 3.19- http://encyclopedia.thefreedictionary.com/Terms%20for

%20anatomical%20location %20anatomical%20location Figure 3.20- Figure 3.20-

http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.html html