Comparative Anatomy General Body Plan

1
Comparative AnatomyGeneral Body Plan
Note Set 2 Chapters 2 4
2
Pharynx (fair-inks) with slits

• Figure 3.1 Pharyngeal arches
• 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

3
Embryo
Figure 3.2 Embryo pharyngeal arches.
Figure 3.3 Embryo development at 1 month.
4
(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.
5
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

6
Figure 3.6 Pharyngeal arches.

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

7
Body Plan

• Head
• Trunk
• Tail

Figure 3.7 Sagittal section of craniate embryo.
8
Head

• Head
• Cephalization- development of sense organs
• Protective covering of dermal bone (not
  replacement bone) or cartilage

Figure 3.8.
9
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.
10
Trunk (cont.)

• Other visceral organ cavities
• Heart- pericardium
• Lungs- pleura
• Abdomen- peritoneum

Figure 3.12 Pericardium and pleural cavities.
Figure 3.11 Pericardium cavities.
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Tail

• From body to end of the digestive tract
• Somites and notochord
• Innervations
• Dorsal and ventral aorta
• Food storage, defense, locomotion

12
Pituitary Development
Figure 3.13

• Stomodeal ectoderm plate pushes inward and forms
  pocket (Rathkes pouch) that leads to anterior
  lobe
• This invagination meets the dienchephalons
  infundibular process which forms the posterior
  lobe

Figure 3.14
13
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

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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

15
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.
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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.
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Anatomical Directions
Figure 3.18.
Figure 3.19.
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Cranial Nerves

• Olfactory
• Optic
• Oculomotor
• Trochlear
• Trigeminal
• Abducens
• Facial
• Vestibulocochlear
• Glossopharyngeal
• Vagus
• Amniotes only
• Spinal Accessory
• Hypoglossal

Figure 3.20
19
Literature Cited

• Figure 3.1- http//www.nature.com/nrg/journal/v2/n
  11/images/nrg1101-858a-i1.gif
• Figure 3.2- http//www.ratbehavior.org/images/Embr
  yoPharyngealArches.jpg
• Figure 3.3- http//islam.org.hk/It_is_the_Truth/so
  mites.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_fate
  s.gif
• Figure 3.6- http//connection.lww.com/Products/sad
  ler/imagebank.asp
• Figure 3.9- http//www.sci.nu.ac.th/biology/elearn
  ing/picture5/7_coelomate.jpg
• Figure 3.11- http//mywebpages.comcast.net/wnor/th
  oraxlesson4.htm
• Figure 3.12- http//faculty.southwest.tn.edu/rburk
  ett/AP20body20cavities.htm
• Figure 3.13- http//people.musc.edu/wilburd/Head
  20and20Neck20I/sld012.htm
• Figure 3.14- http//www.cushings-help.com/rathke.h
  tm
• Figure 3.15- http//cal.vet.upenn.edu/saortho/chap
  ter_62/62mast.htm
• Figure 3.16- http//www.telepathology.com/cases/fo
  rum/case17g.jpg
• Figure 3.17- http//anthro.palomar.edu/primate/foo
  tnote.htm
• Figure 3.19- http//encyclopedia.thefreedictionary
  .com/Terms20for20anatomical20location
• Figure 3.20- http//www.besthealth.com/besthealth/
  bodyguide/reftext/html/nerv_sys_fin.html