Comparative Anatomy Sensory and Endocrine Organs Note Set 14 Chapter 15 & 17

Sense Organs Monitor external & internal environment Somatic or visceral receptors Specific or general

Special Somatic Receptors Neuromasts In skin of fish and amphibians Monitors mech, elect, and chem stimuli Ampullae of Lorenzini in shark snout Figure 16.1: Ampullae of Lorenzini in shark.

Special Somatic Receptors (cont.) Neuromasts Pit organs along shark gill region Lateral line canal Linear series Derived from ectodermal placodes Figure 16.2: External openings of neuromast organs in Squalus. Figure 16.3: Neuromast organ and lateral line canal in a fish.

Special Somatic Receptors Membranous Labyrinth Vertebrates have pair of fluid filled membranous labyrinths Filled with endolymph Surrounded by perilymph Figure 16.5: Membranous labyrinths of human. Figure 16.4: Left membranous labyrinth of craniates; semicircular canals (1, 2, & 3), sacculus (s) and utriculus (u).

Special Somatic Receptors (cont.) Membranous Labyrinth Semicircular canals, utriculus, and sacculus Inside canals: Otoliths Sensory hairs- perceive motion Angular motion detected by semicircular canals Linear motion detected by utriculus and sacculus Figure 16.6: Vestibular apparatus.

Figure 16.7: Human anatomy of the ear. Figure 16.8: Anlagen of amniote inner ear (otocyst). Embryonic head (a) and cross section of head (b).

Special Somatic Receptors (cont.) Membranous Labyrinth Lagena Out pocketing of sacculus wall Gives rise to cochlea in mammals Organ of Corti Figure 16.9: Cochlea and organ of corti in mammal.

Special Somatic Receptors (cont.) Membranous Labyrinth Weberian ossicles Fish transmit sound waves Modified transverse process Sinus impar (some fish) Assists in transport of sound (a) (b) Figure 16.10: (a) weberian ossicles (b) weberian apparatus for transmitting swim bladder vibrations to ear.

Special Somatic Receptors (cont.) Membranous Labyrinth Middle Ear of Tetrapods Canal from evagination of 1st pharyngeal pouch Eustachian tube Communication btwn pharynx and middle ear Figure 16.11: Position of eustachian tube.

Special Somatic Receptors (cont.) Membranous Labyrinth Middle Ear of Tetrapods Bones: Malleus, incus, and stapes Derived from 1st and 2nd visceral arches Stapes is columella in reptiles and birds Figure 16.12: Middle ear bones.

Special Somatic Receptors (cont.) Membranous Labyrinth Middle Ear of Tetrapods Figure 16.13: Development of the middle ear bones.

Special Somatic Receptors (cont.) Membranous Labyrinth Outer Ear of Tetrapods Pinnae Ear drum set back into skull Crocs, birds, and mammals Tympanic membrane on outside Frogs External auditory meatus Canal leading to tympanic membrane

Special Somatic Receptors Infrared Receptors Pits that open to surface Btwn epidermal scales Loreal pits Pit vipers Btwn nostril and eye thermosensitive Labial pits Pythons Other thermosensitive pits Appear similar to neuromasts

Special Somatic Receptors Light Receptors Photoreceptors Lateral eyes Median eye (3rd or pineal eye) On top of head Has lens and cornea Do not form retinal images Ex: lamprey, ganoid fish, larval anurans, lizards Figure 16.14: Parietal eye. Figure 16.15: Parapineal organ of iguana.

Special Somatic Receptors (cont.) Light Receptors Median eye (3rd or pineal eye) (cont.) Part of epiphyseal complex Anterior parapineal is often photosensitive Lamprey- both pineal and parapineal are photosensitive Lizard- parapineal becomes 3rd eye Frontal organs 3rd eye in larval frogs Photosensitive Figure 16.16: Epiphyseal complex of lamprey and embryonic and adult lizard.

Special Chemoreceptors Olfactory Organs Ectodermal placodes Sink into head Internal naris- opening inside Lungfish and tetrapods External naris- opening outside Fish Higher vertebrates possess both types Figure 16.17: Internal and external naris shown and vomeronasal organ.

Special Chemoreceptors (con’t) Olfactory Organs Vomeronasal organ (Jacobson’s Organ) Olfactory mechanisms isolated form nasal Snakes and lizards Insert forked tongue into organ (a) (b) Figure 16.18: Snake collecting scent molecules (a) that are then delivered to the vomeronasal organ by the tongue (b).

Special Chemoreceptors Organs of Taste Taste buds Similar to neuromasts In oral cavity and pharynx Figure 16.19: Anatomy of the taste bud.

Endocrine Organs Ductless organs Secrete hormones Derived from the 3 germ layers Figure 16.20: Embryonic germ layers.

Pituitary Gland Figure 16.21: Phylogeny of the vertebrate pituitary.

Pituitary Gland (Hypophysis) Derived from ectoderm Two divisions Neurohypophysis (post. pit.) Adenohypophysis (ant. pit.) Figure 16.22: Anterior and posterior pituitary.

Pituitary Gland (cont.) Neurohypophysis Infundibulum of diencephalon Stores hormones Adenohypophysis Cells evaginate away from stomadeum Secretes hormones Rathke’s pouch Figure 16.23: Embryogenesis of the amniote pituitary.

Caudal Neurohemal Organ Endocrine gland unique to some fish Urophysis Neurosensory organ Occurs at tip of tail off of spinal cord

Pineal Derived from ectoderm Produces melatonin Gonadal regulator Photoperiodism Figure 16.24: Location of the pineal gland in the human brain.

Adrenal Gland Adrenal Medulla Adrenal Cortex Derived form ectoderm From neurocrest cells Adrenal Cortex Derived from mesoderm Figure 16.25: Cross section of Rt adrenal gland (top) and anatomical position of the adrenal glands.

Gonads Derived from mesoderm Within kidney tissue in some rayfin fish Corpuscles of Stannius

Endodermal Origin Pancreatic Islets of Langerhans Thyroid gland Foramen Cecum- reminant of thyroid evagination Bursa of Fabricius Outpocket of cloaca Thymus in nature Figure 16.27: Mammalian thyroid development.

Pharyngeal Pouches Derived from endoderm Fish Amphibians Pouches 2, 3, 4, 5 (dorsal)- thymus Pouch 5 (ventral)- ultimobranchial bodies Amphibians Pouches 3, 4, 5 (dorsal)- thymus Figure 16.28: Contributions of the embryonic pharyngeal pouches to development of endocrine glands.

Pharyngeal Pouches (cont.) Mammals Pouches 3 & 4 (dorsal)- thymus Pouches 3 & 4 (ventral)- parathyroids No ultimobranchial bodies Figure 16.29: Contributions of the embryonic pharyngeal pouches to development of endocrine glands.

Literature Cited Figure 16.1- http://people.eku.edu/ritchisong/342notes11.html Figure 16.2, 16.4, 16.8, 16.10 (b), 16.15, 16.16 & 16.17- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001. Figure 16.3- http://fig.cox.miami.edu/~cmallery/150/neuro/senses.htm#illusions Figure 16.5- http://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/Earf04/Ear.f04.html Figure 16.6- http://faculty.etsu.edu/currie/study/hearing.htm Figure 16.7- http://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/Earf04/Ear.f04.html Figure 16.9- http://faculty.etsu.edu/currie/study/hearing.htm Figure 16.10 (a) http://www.voiceproblem.org/anatomy/learning.asp Figure 16.11- http://www.familydoctor.co.uk/htdocs/deafness/deafness_specimen.html Figure 16.12- http://137.222.110.150/calnet/Aud/page2.htm Figure 16.13- http://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/Earf04/Ear.f04.html Figure 16.14- http://www.anapsid.org/parietal.html

Literature Cited Figure 16.18- http://www.massasauga.ca/stewardship_guide/section_2/pg16.htm Figure 16.19- http://www.csus.edu/indiv/l/loom/oct19%20f05.htm Figure 16.20- http://www.bme.gatech.edu/vcl/Tissue_Engineering/Background/2_cell_types.htm Figure 16.21, 16.23, 16.27, 16.28 & 16.29- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002. Figure 16.22- http://www.abcbodybuilding.com/magazine03/endocrineinsanity1.htm Figure 16.24- http://webs.uvigo.es/endocrinologia/marco_izquierda.html Figure 16.25- http://www.bartleby.com/61/imagepages/A4adregl.html