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The effects of growth factors on testicular germ cell apoptosis in the stallion
Abstract
Apoptosis is necessary for both initiation and control of spermatogenesis; however, an increase in apoptosis can lead to subfertility/infertility in stallions causing substantial financial loss in the equine industry. The ability of three recombinant growth factors, stem cell factor (SCF), leukemia inhibiting factor (LIF), granulocyte macrophage-colony stimulating factor (GM-CSF), and one hormone, estradiol (E₂), alone or in combination, to prevent apoptosis of germ cells in short-term equine testicular cultures was examined. Two stallions, with normal fertility parameters, were castrated, tissue was sectioned into approximately 2-mm cubes, and placed in medium-filled culture chambers. Concentrations of SCF (100 ng/mL), LIF (10 ng/mL), GM-CSF (5 ng/mL), and E₂ (10⁻⁹ M) were added alone or in combination to each well. After 6 hours in culture, the tissue was fixed and immunohistochemically stained for apoptosis detection using an ApopTag® (TUNEL) kit. Apoptotic cells per 100 Sertoli cell nuclei in each seminiferous tubule were counted until the 500th Sertoli cell nuclei was reached. A paired t-test was used to compare apoptotic rates among treatment groups with statistical significance was determined at p<0.05. Percent differences were also calculated but not analyzed. GM-CSF alone reduced apoptosis (p<0.05). GM-CSF treated tissue combined reduced the mean number of apoptotic cells compared to non-GM-CSF treated tissue combined (p<0.01) and the controls (p<0.05). A reduction was seen between the treatments SCF, LIF, and GM-CSF combined and E₂, SCF, LIF and GM-CSF combined (p<0.05) vs the control. It was hypothesized that E₂, SCF, LIF and GM-CSF would reduce the incidence of apoptosis in testicular germ cells. However, E₂, SCF and LIF, when administered alone, did not significantly reduce apoptosis. Tissue treated with GM-CSF reduced apoptosis when compared to controls. The combined treatment of SCF, LIF and GM-CSF also reduced apoptosis, and the addition of E₂ to SCF, LIF and GM-CSF showed an even greater reduction in apoptosis. These results suggest a possible synergy between the combination of SCF, LIF and GM-CSF and E₂, SCF, LIF and GM-CSF. More research is necessary to determine the role of other growth factors in apoptosis.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 38-47).
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Citation
Donnelly, Casey Leanne (2002). The effects of growth factors on testicular germ cell apoptosis in the stallion. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -D64.
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