ILAR Journal Online, Volume 41(4) 2000: Cryobiology of Embryos, Germ Cells, and Ovaries

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ILAR Journal V41(4) 2000
Cryobiology of Embryos, Germ Cells, and Ovaries

Glossary

activation energy: the amount of energy necessary to initiate a chemical reaction. In a cryobiological context, this term refers to the minimum amount of energy required to move water and/or cryoprotectant molecules across a cellular membrane.

allograft: tissue or organ grafting between individuals that belong to the same species but are not genetically identical

antral follicle: a stage of follicular development; a structure on the ovary that contains an oocyte granulosa cell complex and follicular fluid

assisted breeding: any procedure for propagating an animal other than by natural mating, including artificial insemination, embryo transfer, or in vitro fertilization/embryo transfer

autograft: a tissue or organ that is transplanted to a different part of the same body

biodiversity: the array, or wealth, of species on the planet

bound water: water that is osmotically inactive (i.e., water bound in the structure of macromolecules, such as proteins)

cellular activation energy: expressed as E or Ea, defined in the equation

where Para_o is a parameter such as a membrane permeability coefficient at a known temperature, T_o. E_a is the activation energy of Para, and R is the universal gas constant.

cellular permeability: ability of the cell membrane to allow water or solutes to permeate/penetrate through the membrane

cooling rate: rate of lowering the temperature (e.g., 5°C/min means that the temperature of a sample is reduced by 5°C every 1 min)

critical cooling rate: the initial cooling rate that, due to cellular dehydration through exosmosis, will result in a discrete intracellular concentration of permeating cryoprotectant that will allow intracellular vitrification on the rapid cooling step associated with plunging the sample into liquid nitrogen for ultimate storage

cryoinjury: injury to living cells/tissues at lower temperatures

cryoprotective agent permeation: movement of cryoprotective agents (e.g., ethylene glycol, dimethyle sulfoxide) into cytoplasm through the plasma membrane

cryoprotective agents (CPAs): a class of chemical compound that can prevent or reduce cryoinjury

dehydration curve: a graphical representation of the relationship between cell volume and temperature at a given cooling rate. As extracellular ice forms, extracting pure water, the resulting extracellular solution becomes more concentrated and results in a chemical potential gradient. This gradient causes cellular exosmosis of water and a corresponding cellular volume excursion.

devitrification: the formation of ordered ice crystals during warming of a solution that was previously in the vitrified (glass-like) state

embryo bank: cryopreservation of preimplantation embryos for the purpose of indefinite storage of species or genotypes of animals for future rederivation of breeding stock

estrous cycle synchronization: a treatment or procedure that modifies the estrous cycles of a group of randomly cycling females to the same state and period

exosmosis: the chemical potential gradient-driven movement of water from intracellular to extracellular space

extender (components): a solution used for the dilution and storage of semen, which acts to protect from cold shock as well as add necessary nutrients, buffering capacity, and maintenance of osmotic balance. Common components include milk and/or egg yolk, combined with carbohydrates.

freeze-dried storage: storage of a material from which water and other volatile compounds have been removed by freezing under high vacuum

genome resource bank: the organized collection, storage, and use of biomaterials, including germplasm, embryos, tissue, blood products, and DNA

glass formation: water solidified in the amorphous instead of crystalline form

heterotopic transplantation: transplanting tissue to a body region different from its original site

ice nucleation temperature: temperature at which the first ice crystal is formed in a solution

intracellular freezing: the formation of ice crystals in previously liquid intracellular water

intracellular glass: solidified (vitrified) cytoplasm lacking an ordered crystalline structure

intracellular ice: crystallized water formed within the boundaries of a cytoplasmic membrane

intracellular vitrification: solidified (vitrified) cytoplasm lacking an ordered crystalline structure

intracytoplasmic sperm injection (ICSI): the introduction of a sperm cell into the cytoplasm of a mature oocyte using an injection pipette, potentially resulting in fertilization of the oocyte

membrane permeabilities: the level (rate) at which a substance can traverse a cytoplasmic membrane

nonpermeating solutes: solutes that cannot move across a cell membrane nuclear transfer: reconstructing an embryo by transferring a karyoplast to an enucleated oocyte by micromanipulation and electrofusion

nucleation temperature: the temperature at which ice crystallization commences in a solution; same as ice-nucleation temperature

orthotopic transplantation: transplanting tissue to its original site

osmotic tolerance limits: the cell-specific solute concentration range that has little or no detrimental effect on cellular viability

permeating cryoprotectant: a cryoprotectant that can traverse a cellular cytoplasmic membrane

recrystallization: the formation of destructive intracellular ice crystals through combinations of smaller ice nucleations during the process of thawing

steroidogenic: biosynthesis of steroid hormones (e.g., estrogen, testosterone)

vitrification: solidification of a solution without the formation of an ordered crystalline lattice (ice); same as glass formation

vitrified cytoplasm: cytoplasm that has solidified without the formation of ice

xenograft: taking a tissue or organ from a donor of one species and grafting into a recipient of another species