Comparative Anatomy General Body Plan Note Set 2 Chapters 2 & 4

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

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

Aortic arches housed by pharyngeal arch 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.

1st (mandibular) arch- mandibular and maxillary portions 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 Cephalization- development 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 3.19- http://encyclopedia.thefreedictionary.com/Terms%20for%20anatomical%20location Figure 3.20- http://www.besthealth.com/besthealth/bodyguide/reftext/html/nerv_sys_fin.html