Oocyte activation and sperm lyophilization : implications for intracytoplasmic sperm injection in the bovine /
Intracytoplasmic sperm injection (ICSI) in the bovine has proven to be an inefficient method for obtaining fertilization; however, the technique holds great potential because even dead spermatozoa can be used to create viable embryos. One of the weaknesses of bovine ICSI appears to be the low rates...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728907481&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Intracytoplasmic sperm injection (ICSI) in the bovine has proven to be an inefficient method for obtaining fertilization; however, the technique holds great potential because even dead spermatozoa can be used to create viable embryos. One of the weaknesses of bovine ICSI appears to be the low rates of spontaneous oocyte activation and sperm decondensation. Improvements in activation regimes could be very useful. For the present study the activators ionomycin (Iono), Iono followed by cycloheximide, Iono with butyrolactone-1, Iono with 6-dimethylaminopurine, and porcine sperm extract were evaluated for potential use with ICSI. Evaluation criteria included most of the early and late events associated with oocyte activation: decrease in histone H1 and myelin basic protein kinases, pronucleus formation, DNA synthesis, cleavage and development to blastocyst. Each of the activators tested resulted in a higher rate of activation in the bovine oocytes compared to the unactivated, control oocytes. Overall, the activators which most thoroughly satisfied the evaluation criteria were the Iono/cycloheximide, Iono/6-dimethylaminopurine and sperm extract. These were chosen for use with ICSI with both untreated and lyophilized spermatozoa. It has been shown that lyophilized mouse sperm can fertilize oocytes and a similar achievement in a domestic animal such as the cow could be important for research and conservation purposes. The results of ICSI without exogenous activation confirmed that activation rates were low and that sperm tend to remain condensed after injection. Exogenous activators increased rates of female pronucleus formation in the injected oocytes, but the relative rates of condensed sperm remained constant. Untreated and lyophilized sperm were able to fertilize 36% and 8% of the injected oocytes, respectively when no exogenous activation was provided. When Iono/6-dimethylaminopurine was used after ICSI, fertilization rates were over 40%. Cleavage rates varied from 12-92% for the different ICSI treatments, while rates of development to blastocysts ranged from 0-11%. These results indicate that Iono/cycloheximide, Iono/6-dimethylaminopurine and sperm extract are suitable for bovine ICSI, and that lyophilized sperm can fertilize bovine oocytes. Improvements are still needed to increase the number of sperm that participate in fertilization after ICSI. |
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| Item Description: | Vita. "Major Subject: Veterinary Physiology". |
| Physical Description: | x, 155 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 135-150). |