PubMed · 14552278
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Samuel J Kerstein. 2003. Extra embryos.. https://pubmed.ncbi.nlm.nih.gov/14552278/
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Marine diplonemids (Diplonemidae and Hemistasiidae), once considered difficult to culture, can now be introduced into stable axenic cultures and grown to high densities. This chapter provides detailed protocols on establishing clonal cultures from environmental cells, their axenization and routine maintenance, as well as instructions on mid- and large-scale cultivation, estimation of cell density, and cryopreservation of selected species.
BACKGROUND: In contrast to the technique of conventional freezing, the vitrification of spermatozoa requires high cooling rates (720 000 degrees K/min), which could be damaging for spermatozoa. The aim of our study was to compare slowly frozen and vitrified spermatozoa in terms of their post-thaw DNA integrity and motility. METHODS: Semen samples were prepared according to the routine swim-up technique and divided into aliquots for comparison of fresh, conventionally frozen and vitrified spermatozoa from the same ejaculate in the presence or absence of cryoprotectants. Spermatozoa motility and DNA integrity were determined. RESULTS: The motility of spermatozoa conventionally (slowly) frozen with a cryoprotectant was similar to that recorded for spermatozoa vitrified in the absence of cryoprotectant (47 versus 52%). The DNA integrity was unaffected by the cryopreservation method or presence of cryoprotectants. CONCLUSION: The vitrification of human spermatozoa in the absence of conventional cryoprotectants is indeed feasible. The DNA integrity of vitrified sperm is comparable with that shown by standard slow-frozen/thawed spermatozoa, yet the method is quick and simple and does not require special cryobiological equipment.
REVIEW: The outcome of freeze-thaw cycles with pronuclear stage oocytes or embryos, derived from collecting cycles stimulated with gonadotropin-releasing hormone (GnRH)-antagonists' protocols, was reviewed. CONCLUSION: The viability of cryopreserved pronuclear stage oocytes and embryos, the quality of transferred embryos and the pregnancy rates of the freeze-thaw cycles seem to be satisfactory regardless of the type and dose of GnRH-antagonist.