To investigate the causes of the occurrence and persistence of porcine cystic follicles, we evaluated the apoptosis and proliferation of follicular cells in these cysts. Apoptotic frequencies were examined by TUNEL assay and the expression of apoptosis regulators (XIAP, bax, bc1-2 and caspase-3) by immunohistochemistry, Western blotting and real-time quantitative PCR; cell proliferation activity was evaluated by PCNA immunohistochemistry and proliferation of in vitro cultured granulosa and theca cells. The low apoptotic frequency and weak proliferative activity were found in cystic follicles. Low frequency of apoptosis might be associated with decreased amounts of apoptotic-related factors (bax and caspase-3) and increased amounts of anti-apoptotic factors (XIAP and bcl-2) in cystic follicles. Significantly lower proliferation activity was detected in granulosa and theca cells from cystic follicles, and lesser PCNA-positive cells were found in cystic follicles. Our results indicate that the programmed cell death and cell proliferation system were altered in cystic follicles. The disorder between apoptosis and proliferation was responsible for maintaining a static condition without degeneration, which leads to the long-term persistence of follicles. These findings provide important novel insights into the pathogenesis of follicular cysts in sows.

Lead telluride (PbTe) with rock-salt structure was successfully obtained by a high-pressure and high-temperature (HPHT) method. The orientation of the PbTe samples varies with pressure increase. The results—a decrease in the Seebeck coefficient, resistivity and thermal conductivity of PbTe with pressure but an increase in the thermoelectric power figure σS2—indicate that the figure of merit Z of PbTe samples can be improved several times over by using HPHT.

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High-pressure in situ energy-dispersive x-ray diffraction experiments on GaN nanocrystals with 50 nm diameter have been carried out using a synchrotron xray source and a diamond-anvil cell up to about 79 GPa at room temperature. A pressure-induced first-order structural phase transition from the wurtzite-type structure to the rock-salt-type structure starts at about 48.8 GPa. The rock-salttype phase persists to the highest pressure in our experimental range.

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