Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8464340 | Cryobiology | 2018 | 6 Pages |
Abstract
The rate at which lethal intracellular ice forms during sperm cryopreservation is highly dependent on the cooling protocol. The present work compares two cooling protocols for use with Iberian ibex (Capra pyrenaica) sperm by assessing the effects on the motility, viability, and size of frozen-thawed sperm cells. Ejaculates, obtained from six adult ibex males via transrectal, ultrasound-guided massage of the accessory sex glands plus electroejaculation if necessary, were cooled via either 1) Protocol 1 (decelerating cooling), involving cooling in liquid nitrogen vapor from 5â¯Â°C to â35â¯Â°C (40â¯Â°C/min), from â35â¯Â°C to â65â¯Â°C (17â¯Â°C/min), and then from â65â¯Â°C to â85â¯Â°C (3â¯Â°C/min); or 2) Protocol 2 (accelerating cooling) involving cooling in a biological freezer from 5â¯Â°C to â5â¯Â°C (4â¯Â°C/min), from â5â¯Â°C to â110â¯Â°C (25â¯Â°C/min), and then from â110â¯Â°C to â140â¯Â°C (35â¯Â°C/min). Compared to fresh ejaculates, sperm quality at thawing was found to be reduced by both protocols (pâ¯<â¯.05), but especially by Protocol 1. Sperm head size was also significantly reduced by both protocols, although the Protocol 1 sperm heads were also significantly smaller than those of Protocol 2 sperms heads (pâ¯<â¯.05). In fresh sperm samples, clustering analyses revealed two subpopulations of sperms with different morphometric characteristics, SP1 with larger cells, and SP2 with smaller cells. Both cooling protocols caused reduction in the proportion of SP1 cells, and an increase in the proportion of SP2 cells. In conclusion, the decelerating cooling protocol (Protocol 1) caused greater cryodamage to the sperm cells than the accelerating protocol (Protocol 2).
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Authors
Milagros C. Esteso, Adolfo Toledano-DÃaz, Cristina Castaño, Jorgea Pradiee, Antonio Lopez-Sebastián, Julián Santiago-Moreno,