Archive for the ‘Ovary’ Category


Superovulatory Response of One Ovary: DISCUSSION(8)

May 2, 2013 Author: Walter Mcneil | Filed under: Ovary

DISCUSSION(8)

Number of primordial follicles was not correlated as well with superovulatory response. The time required for early preantral follicles to reach ovulatory size has been estimated, by extrapolation, to be 80-100 days in the cow, 6 mo in the ewe, and 84 days in the sow. Therefore, in a situation when a donor cow might be superovulated every 2-3 mo, environmental factors, such as nutritional stress or heat stress, could have an effect on the growth of these preantral follicles and affect the subsequent superovulatory response when the follicles reach the antral stage. In contrast, there is a higher repeatability among number of follicles available for ovum pickup twice weekly. This shows that in the short term, the size of cohorts within a cow is highly repeatable. Even with ovum pickup, however, there are long-term trends toward changes in the size of cohorts, suggesting environmental influences on the preantral follicle population. buy yasmin online

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  • Superovulatory Response of One Ovary: DISCUSSION(7)

    May 1, 2013 Author: Walter Mcneil | Filed under: Ovary

    There were also fewer surface follicles, primarily small (1-3 mm) and medium (3-7 mm) follicles, in the Low superovulatory response group. On the basis of the concept that folliculo-genesis is a long process in the cow, we are currently pursuing the idea of long-term modification of the pool of growing follicles to improve superovulatory response. Typically, superovulation treatments have been used to increase the number of follicles growing to ovulatory size within a 3- to 5-day window of time during diestrus. Although the size of the primordial pool is set at birth, it might be possible to increase the rate of activation of primordial follicles into the growing pool and subsequently increase the number of follicles that survive to the tertiary stage at which they can respond to superovulatory treatments. In this manner, a cow that would normally be a Low responder could be converted to a Medium or High responder. buy ventolin inhalers

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  • Superovulatory Response of One Ovary: DISCUSSION(6)

    Apr 30, 2013 Author: Walter Mcneil | Filed under: Ovary

    DISCUSSION(6)

    The quadratic relationship between the number of medium surface follicles and the number of CL suggests that an increase beyond approximately 21 medium follicles does not add to the number of follicles that are ovulated in response to FSH-P. At this point, another factor, such as the amount of FSH administered or spacial restrictions on the surface of the ovary, may become rate limiting to the number of follicles that can grow to ovulatory size. The linear relationship between number of CL and number of tertiary follicles was based on counting a sample of tissue, not on an estimate of tertiary follicles in the whole ovary.

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  • Superovulatory Response of One Ovary: DISCUSSION(5)

    Apr 29, 2013 Author: Walter Mcneil | Filed under: Ovary

    Gong et al. noted a similar correlation between the number of small surface follicles and superovulatory response; however, in their study, follicles were measured by ultrasound and the size classifications were slightly different from ours. In our study, dimensions of individual small and medium surface follicles were not recorded; thus, we were unable to reclassify the data to compare directly our results with those of Gong et al.. The fact that the number of medium follicles was correlated with superovulatory response is in good agreement with other data of Gong et al., demonstrating that the pool of antral follicles that grow in response to FSH is selected from follicles that are about 34 mm in diameter. flovent inhaler

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  • Superovulatory Response of One Ovary: DISCUSSION(4)

    Apr 28, 2013 Author: Walter Mcneil | Filed under: Ovary

    DISCUSSION(4)

    Proof that atresia may occur in bovine preantral follicles can be found in the work of Erickson. In a period of 40 days, the number of follicles in the fetal ovary decreased from 2 500 000 to 108 000. There would have to be some atresia of preantral follicles because not all these follicles could grow to the antral stage in this short time. While the current study did not examine atresia rates, Hirshfield demonstrated that in the rat there is very little atresia during the first several generations of granulosa cell division, with the rate of atresia increasing in the late secondary stage. It is possible that the lack of correlation between primary and secondary follicles in the current study may be due to the experimental sampling method. buy birth control online

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  • Superovulatory Response of One Ovary: DISCUSSION(3)

    Apr 27, 2013 Author: Walter Mcneil | Filed under: Ovary

    Based on the total number of microscopic follicles for each cow, cows were classified as having Optimal or Sub-optimal populations of follicles. Classification was based on a clear demarcation in the frequency of cows with different numbers of follicles. Thus, cows in the Suboptimal category had a maximum of 100 microscopic follicles whereas those in the Optimal category had a minimum of 250 microscopic follicles. The cause of this difference is unknown, but cows in the Suboptimal category had fewer FSH-responsive follicles as indicated by the lower superovulatory response. These differences in number of follicles probably originated during early folliculogenesis or before puberty, because Erickson found differences among heifers as early as 2 mo of age. ventolin 100 mcg

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  • Superovulatory Response of One Ovary: DISCUSSION(2)

    Apr 26, 2013 Author: Walter Mcneil | Filed under: Ovary

    DISCUSSION(2)

    Although one cannot establish cause-and-effect relationship through correlation analysis, support for a causal link comes from the observations that the regression of the number of CL on the number of tertiary follicles showed a positive linear relationship and that Low responders had fewer tertiary follicles than Medium or High responders. proventil inhaler

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  • Superovulatory Response of One Ovary: DISCUSSION(1)

    Apr 25, 2013 Author: Walter Mcneil | Filed under: Ovary

    We believe that this is the first study to examine relationships between histological and surface populations of follicles in one ovary and superovulatory response of the other ovary in cattle. Clearly, we have demonstrated that cows that had a low response to superovulation with FSH-P had fewer primordial and tertiary follicles. These cows also had fewer total surface follicles, mainly attributable to fewer small (1-3 mm) and medium (3-7 mm) follicles. Moreover, cows that had fewer microscopic follicles had fewer small (1-3 mm) follicles and CL. Cheap Diskus Advair

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