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The effects of growth factors on testicular germ cell apoptosis in the stallion
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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.
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Includes bibliographical references (leaves 38-47).
Issued also on microfiche from Lange Micrographics.
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
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