Progress and challenges of fish sperm vitrification: A mini review Miaomiao Xin a, * , Mohammad Abdul Momin Siddique a, b, ** , Borys Dzyuba a , Rafael Cuevas-Uribe c , Anna Shaliutina-Kole  sov  a a , Otomar Linhart a a Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research, Institute of Fish Culture and Hydrobiology, University of South Bohemia in Ceske Budejovice, Vod nany, Czech Republic b Department of Oceanography, Noakhali Science and Technology University, Sonapur, Noakhali, Bangladesh c Department of Fisheries Biology, Humboldt State University, One Harpst St., Arcata, CA, 95521, USA article info Article history: Received 26 November 2016 Received in revised form 5 April 2017 Accepted 27 April 2017 Available online 27 April 2017 Keywords: Cryopreservation Cryoprotectant Fish sperm motility Fertilization abstract To survive low temperature is required for a long-term storage (cryopreservation), cells should be vitrified to a state in which intracellular water is solidified without ice crystal formation. Two different approaches are described for fish sperm cryopreservation: 1) sperm conventional cryopreservation, in which extracellular water is partially crystallized and 2) sperm vitrification, in which both intra- and extra-cellular liquids are vitrified. Sperm vitrification has been applied to some fish species with limited success. Traditional vitrification requires rapid cooling/warming rates, small sample carriers, and using high permeable cryoprotectant concentrations. The latter cause cytotoxic effects which must be well managed and will require continuous effort to match an appropriate cryoprotectant with suitable apparatus and warming methods. Novel cryoprotectant-free sperm vitrification approach has been applied to several fishes. This review summarizes development of basic procedures and discusses ad- vantages and disadvantages of vitrification when applied it to fish sperm. © 2017 Elsevier Inc. All rights reserved. 1. Introduction Vitrification has become an increasingly popular method of preserving the cells and tissues by using permeable cryoprotectant concentrations which will develop an amorphous glassy state, while preventing intracellular and extracellular ice crystallization [1,2]. First reported in 1937, there has been recent renewal of in- terest after a long latent period [3]. During the last decade, scien- tists keep their attention on human sperm vitrification without any permeable cryoprotectants [4]. Researchers feel that vitrification might offer the capability to cryopreserve cells using simple and fast procedures needing no specialized equipment [4,5]. Successful vitrification of fish gametes requires high concen- trations of permeable cryoprotectants, and a rapid temperature change. Vitrification has been applied for fish primordial germ cells [6], oocytes [7], eggs [8], testicular tissues [9] and embryos [10]. Spermatozoa were the first mammalian cell to be cryopreserved by slow-cooling using glycerol as a cryoprotectant [11]. The use of vitrification on fish spermatozoa is relatively a new application. Several scientists have tested vitrification on fish sperm; they have mainly focused on permeable cryoprotectant toxicity at various concentrations, exposure times, and temperatures [12,13]. Tradi- tional vitrification on spermatozoa has been tested with limited success on: Russian sturgeon Acipenser gueldenstaedtii [14], Persian sturgeon A. persicus [15], rainbow trout Oncorhynchus mykiss [16], channel catfish Ictalurus punctatus [17], green swordtail Xipho- phorus hellerii [18], spotted seatrout Cynoscion nebulosus, red snapper Lutjanus campechanus, red drum Sciaenops ocellatus [19], Atlantic salmon Salmo salar [20], Tambaqui Colossoma macro- pomum [21], Eruasian perch Perca fluviatilis, and European eel Anguilla anguilla [22], while only few studies carried out on fish sperm by cryoprotectant-free vitrification [23,24]. The aim of this review is to (1) summarize the basic procedures of vitrification of fish sperm (2) discuss the current progresses in vitrification application for fish spermatozoa (3) compare the ad- vantages and disadvantages of vitrification, and (4) to provide * Corresponding author. Faculty of Fisheries and Protection of Waters, University of South Bohemia in Ceske Budejovice, Z ati sí 728/II, 389 25, Vod nany, Czech Republic. ** Corresponding author. Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Research, Institute of Fish Culture and Hydrobiology, University of South Bohemia in Ceske Budejovice, Vod nany, Czech Republic. E-mail addresses: mxin@frov.jcu.cz (M. Xin), siddique@frov.jcu.cz (M.A.M. Siddique), linhart@frov.jcu.cz (O. Linhart). Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com http://dx.doi.org/10.1016/j.theriogenology.2017.04.043 0093-691X/© 2017 Elsevier Inc. All rights reserved. Theriogenology 98 (2017) 16e22