title: Sperm cell population dynamics in ram semen during the cryopreservation process.
abstract: BACKGROUND
  Sperm cryopreservation has become an indispensable tool in biology. Initially, studies were aimed towards the development of efficient freezing protocols in different species that would allow for an efficient storage of semen samples for long periods of time, ensuring its viability. Nowadays, it is widely known that an important individual component exists in the cryoresistance of semen, and efforts are aimed at identifying those sperm characteristics that may allow us to predict this cryoresistance. This knowledge would lead, ultimately, to the design of optimized freezing protocols for the sperm characteristics of each male.
  
  
  RESULTS
  We have evaluated the changes that occur in the sperm head dimensions throughout the cryopreservation process. We have found three different patterns of response, each of one related to a different sperm quality at thawing. We have been able to characterize males based on these patterns. For each male, its pattern remained constant among different ejaculates. This latter would imply that males always respond in the same way to freezing, giving even more importance to this sperm feature.
  
  
  CONCLUSIONS
  Changes in the sperm head during cryopreservation process have resulted useful to identify the ability of semen of males for freezing. We suggest that analyses of these response patterns would represent an important tool to characterize the cryoresistance of males when implemented within breeding programs. We also propose follow-up experiments to examine the outcomes of the use of different freezing protocols depending on the pattern of response of males.
authors.affiliation: CERSYRA, Junta de Comunidades de Castilla-La Mancha, Valdepeñas, Spain. mramon@jccm.es
authors.forename: Manuel
authors.initials: M
authors.lastname: Ramón
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Pérez-Guzmán
authors.forename: Pilar
authors.initials: P
authors.lastname: Jiménez-Rabadán
authors.forename: Milagros C
authors.initials: MC
authors.lastname: Esteso
authors.forename: Olga
authors.initials: O
authors.lastname: García-Álvarez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Maroto-Morales
authors.forename: Luis
authors.initials: L
authors.lastname: Anel-López
authors.forename: Ana J
authors.initials: AJ
authors.lastname: Soler
authors.forename: M Rocío
authors.initials: MR
authors.lastname: Fernández-Santos
authors.forename: J Julián
authors.initials: JJ
authors.lastname: Garde
mesh_terms: D000818:Animals; D002452:Cell Count; D015925:Cryopreservation / Q000379:methods*; D008297:Male; D012661:Semen / Q000166:cytology*; D012756:Sheep / Q000378:metabolism*; D013077:Sperm Head; D013090:Spermatocytes / Q000166:cytology*
references.citation: J Androl. 2003 Sep-Oct;24(5):746-56
references.pmid: 12954668
references.citation: Biol Reprod. 2004 Jul;71(1):28-37
references.pmid: 14973261
references.citation: Reprod Domest Anim. 2010 Jun;45 Suppl 2:67-78
references.pmid: 20591067
references.citation: Theriogenology. 2009 Jul 15;72(2):160-8
references.pmid: 19349069
references.citation: Cryobiology. 1989 Feb;26(1):1-29
references.pmid: 2924590
references.citation: Cryobiology. 2000 Sep;41(2):167-73
references.pmid: 11034795
references.citation: J Androl. 1990 Jan-Feb;11(1):73-88
references.pmid: 2179184
references.citation: J Androl. 1998 Nov-Dec;19(6):704-9
references.pmid: 9876021
references.citation: Biol Reprod. 2002 Mar;66(3):545-54
references.pmid: 11870056
references.citation: J Bioenerg Biomembr. 1989 Feb;21(1):3-19
references.pmid: 2651426
references.citation: J Reprod Fertil Suppl. 2001;57:371-6
references.pmid: 11787178
references.citation: Anim Reprod Sci. 2007 Jul;100(1-2):61-72
references.pmid: 16904275
references.citation: Anim Reprod Sci. 2009 Aug;114(1-3):81-8
references.pmid: 19013731
references.citation: Biol Reprod. 1997 Apr;56(4):991-8
references.pmid: 9096883
references.citation: Cryo Letters. 2002 Jul-Aug;23(4):255-62
references.pmid: 12391486
references.citation: Int J Androl. 2006 Dec;29(6):583-91
references.pmid: 17121656
references.citation: Cryobiology. 1989 Feb;26(1):64-9
references.pmid: 2924593
references.citation: Theriogenology. 2012 Nov;78(8):1682-99
references.pmid: 23062722
references.citation: Theriogenology. 2012 May;77(8):1661-72
references.pmid: 22341709
references.citation: Theriogenology. 2003 Apr 15;59(8):1725-39
references.pmid: 12566147
references.citation: Theriogenology. 2003 Sep 1;60(4):743-58
references.pmid: 12832022
references.citation: Reproduction. 2004 Dec;128(6):829-42
references.pmid: 15579601
references.citation: Theriogenology. 2000 Jan 1;53(1):47-58
references.pmid: 10735061
references.citation: Cryobiology. 1986 Apr;23(2):116-25
references.pmid: 3084174
references.citation: J Androl. 2005 Nov-Dec;26(6):716-23
references.pmid: 16291966
references.citation: Reproduction. 2007 Jul;134(1):111-21
references.pmid: 17641093
references.citation: Theriogenology. 2010 Mar 1;73(4):437-48
references.pmid: 20018357
references.citation: J Androl. 2001 May-Jun;22(3):382-94
references.pmid: 11330638
references.citation: Zygote. 2007 Aug;15(3):257-66
references.pmid: 17637107
references.citation: Biol Reprod. 2005 Feb;72(2):316-27
references.pmid: 15385419
references.citation: Theriogenology. 2008 Dec;70(9):1498-506
references.pmid: 18692226
references.citation: Proc Biol Sci. 1998 Feb 7;265(1392):243-8
references.pmid: 9493409
references.citation: Reprod Domest Anim. 2006 Jun;41(3):241-6
references.pmid: 16689889
references.citation: PLoS One. 2011;6(6):e20530
references.pmid: 21698278
references.citation: Theriogenology. 2004 Oct 1;62(7):1292-306
references.pmid: 15325556
references.citation: Zygote. 2004 May;12(2):117-24
references.pmid: 15460106