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Date of Award

Spring 2004

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Dr. Gary Radice

Abstract

The lymphatic system is a subsystem of the circulatory system that, by returning excess interstitial fluid back into the blood, helps regulate fluid volume and eliminate waste (Leithold 2002). The lymphatic systems of most organisms employ only a form of passive movement, yet certain species of birds, reptiles, and amphibians, such as frogs and salamanders, also have actively beating hearts to supplement the passive movement. The development of lymphatic hearts in the axolotl, Ambystoma mexicanum, has not been well documented at current times. Though the existence of actively beating lymphatic hearts in the axolotl was made over a century ago, research endeavors have focused primarily on birds and other amphibians, namely frogs and toads. The importance of this lies in the need for a deeper understanding as to what mechanisms are used to direct the placement, differentiation, and pattern of development of these lymph hearts. One of the foremost questions asks why the axolotls, A. mexicanum, make 2 parallel lines of lymph hearts all along the dorsal side of their body, whereas the Xenopus sp. simply produces them at their extreme anterior and posterior regions.

Through a series of dissection, dehydration, staining, and microscopic observation of Ambystoma mexicanum specimens, our research has found that that axolotls at or near maturity do not have lymphatic hearts existing in parallel pairs all down the dorsal side of their body. They merely have 3 posterior pairs of lymph hearts and 1 anterior pair, a combination quite comparable to the morphology of frogs. This suggest that the intermediary lymph hearts throughout the torso previously observed and described by researchers such as Kampmeier (1969) might, in fact, degenerate upon maturation of Ambystoma mexicanum.

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