Factors influencing the skin shedding phenomenon in the garter snake Thamnophis sirtalis.
Item
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Title
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Factors influencing the skin shedding phenomenon in the garter snake Thamnophis sirtalis.
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Identifier
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AAI8801697
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identifier
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8801697
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Creator
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Contard, Paul Christopher.
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Contributor
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Adviser: Paul F. A. Maderson
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, General
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Abstract
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The skin shedding phenomenon in garter snakes (Thamnophis sirtalis) was studied. The actual "shedding" of the outer epidermal generation is preceded by the completion of a newly synthesized inner generation (the renewal phase). Onset of the epidermal renewal phase is marked by the appearance of a dullness over the animal's body, particularly the spectacle of the eye (the so-called cloudy eye phase). Epidermal biopsies were removed to determine the stage of the shedding cycle and for ultrastructural analysis. Both endogenous (ie. thyroid hormone) and exogenous (ie. environmental temperature and ambient relative humidity) factors were investigated utilizing both intact and thyroidectomized animals.;Exposure to constant high ambient temperature induced a single shed in a large majority of intact garter snakes. Repeat sheds occurred only in a few animals infected with skin fungus. A majority of intact animals shed when transferred directly to high constant temperature (28{dollar}\sp\circ{dollar}C) after having spent six, ten, or fourteen weeks at very low constant temperature (3{dollar}\sp\circ{dollar}C). Synchrony of onset of the renewal phase was observed among these animals. Maintenance of intact animals under conditions of constant low relative humidity and high temperature (28{dollar}\sp\circ{dollar}C) also induced sheds in most experimental animals. A moderate degree of synchrony of onset of the renewal phase was observed in this group. Feeding appeared to have no effect on skin shedding in any of animals.;Renewal phases occured in all thyroidectomized garter snakes maintained at temperatures of 21{dollar}\sp\circ{dollar}C and higher. These animals appeared to lose the ability to actually "shed." While some continued to shed following the first two renewal phases, none of the animals did so following the third renewal phase. The outer epidermal generations appeared to stack one on top of the other. Thyroidectomized animals lost weight rapidly and died when original weight decreased by 20+%. Feeding appeared to have no affect on skin renewal, shedding, or viability in these animals. Ultrastructural analysis of skin biopsies removed from these snakes revealed morphological defects in the organelles responsible for epidermal lipid synthesis.;Roles of epidermal lipid metabolism and cutaneous water loss are addressed. (Abstract shortened with permission of author.).
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
