EXTERNAL ANA ANAT TOMY OF THE FROG FROG Jeremy G. Vicencio Departme Depa rtment nt of Biol Biology ogy (UP (UPM-CA M-CAS) S) 1st Semester, A.Y. 2010-2011
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Why do we study frogs? 1. They They sho show w both both pri primi miti tive ve and adv advanced anced vertebrate structures 2. The positi position on of their their int interna ernall orga organs ns is is simi similar lar to that of humans 3. They They are are smal smalll and and rea readil dily y av availab ailable le
Ext Externa ernall Ana Anatomy omy of the the Frog Frog
Ext Externa ernall Ana Anatomy omy of the the Frog Frog Part
Description/Function
External nares
Located near the snout or tip of the head, leads to the olfactory organs within
(Dorsal) Upper eyelid
Immovable
(Ventral) Lower eyelid
Can close over the entire eye
Nict Nictit itat atin ing g mem membr bran ane e
Mova Movabl ble e tr transl ansluc ucen entt lo lower wer eye eyeli lid, d, prot protec ects ts the the ey eye whe when n the frog is underwater and serves to moisten the eye when it is on land
Browspot
Located at the top of the head between the eyes which has the diameter of about a pin, a remnant of a median, light-sensitive eye that characterized primitive groups of fishes and amphibians
Tympa ympani nicc memb membrrane ane
Disc Disc-s -sha hape ped d area area pos posterio eriorr to to each each eye, eye, ear eardrum drum//out outer ear
Ext Externa ernall Ana Anatomy omy of the the Frog Frog Part
Description/Function
Cloa Cloaca call aper apertu turre
Comb Combin ined ed orif orific ice e of the the dige digest stiv ive e and and urog urogen enit ital al trac tracts ts at the the posterior end of the trunk just dorsal to the junction of the hind legs
Forelimbs
Emerge from the chest region behind the head, extends into three distinct regions: brachium (upper arm), antebrachium (forearm), manus (hand)
Manus
Comprised of the carpus (wrist), metacarpus (palm), and four digits or fingers
Hindlimbs
Emerge from the waist region and can be partitioned into: thigh (upper leg), shank/crus (lower leg), pes leg), pes (long foot)
Foot
Divided into tarsus (long ankle), metatarsus (instep) , , and five fully-webbed toes or digits
Prehall Prehallux ux or calcar calcar Rudiment Rudiment of the the sixth sixth missin missing g toe, toe, appear appearss medially medially to the the firs firstt toe as a small spur-like outgrowth
Ext Externa ernall Ana Anatomy omy of the the Frog Frog Part
Description/Function
Vocal Sac
Sound-resonating throat pouch of male frogs and toads. They are outpocketings outpocketings of the floor of the mouth, mouth, or buccal cavity. cavity.
Toads oads vs. vs. Frog Frogss
Toads oads vs. vs. Frog Frogss
Males vs. Females
Males vs. Females
Males vs. Females
Males vs. Females
Male Vocal Sacs
Pith Pithin ing g of the the fr frog
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Pithing is the destruction of the central nervous system by piercing the brain and/or spinal cord. This procedure is used in experiments to render the animal unconscious so that it feels no pain. Single Single-pi -pithe thed d frog frog – only the brain is destroyed Double Double-pi -pithe thed d frog frog – spinal cord is destroyed as well
Procedure 1.
Ther There e ar are two two acce accept pted ed meth method odss for for pith pithin ing g a fr frog. og.
2.
One One met metho hod d of of sin singl gle e pit pithi hing ng a fr frog ent entails ails hold holdin ing g the animal in a paper towel with its dorsal side up and with the index finger pressing the nose down so that the head makes a right angle with the trunk.
3.
Loca Locate te the the slig slight ht depr depres essi sion on forme ormed d by the fir first vertebra vertebra and skull about 3 mm behind the line joining the posterior borders of the tympanic membrane. This groove represents the area of the foramen magnum.
4.
Care Carefu full lly y ins inser ertt a long, long, shar sharpp-ti tipp pped ed need needle le or probe probe into the foramen magnum and direct it forward and a little downward.
5.
Exer Exertt a stea steady dy pre press ssur ure e and and rota rotate te it, it, mov movin ing g it it fr from side to side in the cranial cavity to destroy the brain.
4.
5.
Carefu Care full lly y ins inser ertt a lo long, ng, sh shar arpp-ti tipp pped ed ne need edle le or pr probe obe into the foramen magnum and direct it forward and a little downward.
Procedure Exer Ex ertt a st stea eady dy pre press ssur ure e and and ro rota tate te it it,, mov movin ing g it it fr from
side to side in the cranial cavity to destroy the brain. 6.
To dou doubl ble e pit pith h the the frog, frog, inse insert rt the the nee needl dle e int into o the the vertebral vertebral canal, directing d irecting it downward until it has reached the end of the canal. Move the needle from side to side as you go.
7.
A sec secon ond d acc accep epta tabl ble e met metho hod d to to sin singl gle e pit pith h a fr frog involves involves holding the animal in a paper towel with its dorsal side up and inserting one blade of a pair of scissors into the animal’s mouth and cutting off the top of the head just posterior to the eyes.
8.
To dou doubl ble e pit pith h the the anima animal, l, inse insert rt a long long-s -sha harp rp tipp tipped ed needle or probe into the th e exposed vertebral column and direct it downward until it has reached the end of the canal, moving the needle from side to side as you go.
Amitrano, R, & Tortora, GJ. (2007). Laboratory Exercises in Anatomy and Physiology with Cat Dissections
Pith Pithin ing g of the the fr frog
Amitrano, R, & Tortora, GJ. (2007). Laboratory Exercises in Anatomy and Physiology with Cat Dissections
