Physiological differences beween fertilized and unfertilized mouse ova: glycerol permeability and freezing sensitivity
The glycerol permeability and freezing sensitivity of mouse ova were studied for evidence of differences associated with fertilization. The times of ovulation, fertilization and first cleavage of ova were determined as a function of time after the administration of human chorionic gonadotropic, hormone, HCG, to female mice. Fertilization did not cause a large instantaneous change in glycerol permeability. Rather, the permeability coefficient for glycerol at approximately 3/sup 0/C gradually increased from 7.0 x 10/sup -7/ to 7.0 x 10/sup -6/ cm/min for fertilized ova isolated from about 1 hour to 16 hours after fertilization. The zonae pellucidae of fertilized and unfertilized ova did not act as detectable barriers to permeation by glycerol. No significant and immediate change was observed on the surface of the ovum as a result of fertilization. Survival after freezing was assayed by two techniques: measurement of the ability of the cells to fluoresce in the presence of fluorescein diacetate; successful development in culture. Survival of fertilized and unfertilized ova increased as a function of both the temperature and time of incubation in glycerol prior to freezing. It was concluded that permeation of a cell by glycerol enhances survival. The cooling rate that yielded optimal survival of zygotes in G/sub 2/ phase differed from that of unfertilized ova and zygotes in G/sub 1/ phase. The optimum rate for the latter cells was about 1/sup 0/C/min with survival being about 63 percent and 79 percent, respectively. The optimum rate for zygotes in G/sub 2/ ranged from 1/sup 0/C/min to 7/sup 0/C/min with survival being about 58 percent. The differences among the freezing sensitivities of unfertilized ova, zygotes in G/sub 1/ and zygotes in G/sub 2/ can be explained in terms of their differences in glycerol permeability and possibly in terms of the increased surface area associated with the number of microvilli on the G/sub 2/ zygotes.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 7298146
- Report Number(s):
- TID-27706
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ANIMALS
BIOLOGICAL EFFECTS
FREEZING
GAMETES
GERM CELLS
GLYCEROL
HYDROXY COMPOUNDS
MAMMALS
MEMBRANE TRANSPORT
MICE
ONTOGENESIS
ORGANIC COMPOUNDS
OVA
OVULATION
PERMEABILITY
PHYSIOLOGY
REPRODUCTION
RODENTS
SENSITIVITY
SURVIVAL TIME
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
VERTEBRATES
ZYGOTES