Eric Zepnewski


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short tongued L. caerulea
filmed at 250 fps

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B. woodhousii

“super” elongator B. woodhousii
Filmed at 250 fps
Connective tissue plays an important role in vertebrate biomechanics. For my thesis work I have been looking at how connective tissue can affect muscle mechanics. As it turns out, collagen plays an important role in determining how vertebrate skeletal muscle will behave when activated. Skeletal muscle is usually surrounded by helicaly wound collagen fibers. The angle of these fibers to the long axis of the muscle can determine whether the muscle will elongate or shorten upon contraction. The frog tongue provides an excellent model to study this phenomenon. The anuran tongue is comprised of mostly muscle and connective tissue. The angle of the collagen fibers within the tongue musculature can determine how far a frog can protract its tongue. I looked at collagen fiber angles within frogs with tongues of variable protrusibilty. Litoria represents a frog with a short tongue. Rana has a moderately long tongue, while Bufo represents a super elongator. We hypothesised that the collagen fiber angle would correspond to tongue elongation. We used two methods to measure that angle. histology coupled with polarized light microscopy and muscle digestion coupled with Scanning electron microscopy (SEM).
Bufo woodhousi
Bufo woodhousi
Rana pipiens
Rana pipiens
Litoria caerulea
Litoria caerulea
the helicaly crossed fibers within the tongue of R. pipiens
Sem pict showing the helicaly crossed fibers within the tongue of R. pipiens. Magnification – 3000X
Frontal section of the tongue of B. woodhousii
Frontal section of the tongue of B. woodhousii as seen under polarized light.

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