Effects of radiocobalt irradiation of unfertilized or fertilized rabbit OVA in vitro on subsequent fertilization and development in vivo
Freshly shed rabbit ova recovered from the Fallopian tubes were irradiated with a radiocobalt source at 45 r to 32,000 r and then transplanted into the left tube of mated rabbits. The ova were recovered and examined microscopically 10 hours to 24 hours, two days and 6 days after transplantation for the determination of fertilization, cleavage, and blastocyst formation. The fetus and uterine contents were examined macroscopically 22 to 25 days after transplantation. The proportion of fertilized ova decreased from 71% at a very low dosage, 45 r, to 46% at a very high dosage, 32,000 r. The proportion of normally cleaved ova and normal lilastocysts decreased from about 95% at 45 r, to about 3% at 500 r, to 0% at 6,500 r. The proportion of embryonic development decreased from 49% at 45 r, to 21% at 90 r, to 0% at 800 r. A chromosomal bridge was observed in an ovum irradiated at 6,500 r. Failure of second polar body division in one out of 23 ova irradiated at 6,500 r and polyspermy in one out of 32 ova irradiated at 32,000 r before fertilization was observed. When fertilized rabbit ova at the two cell stage were irradiated at 45 r to 6,500 r and examined at various times after transplantation, it was found that the proportion of normal cleavage decreased from 78% at 45 r to 33% at 800 r, to 0% at 6,500 r. The proportion of normal blastocysts decreased from 61% at 45 r, to 20% at 800 r, to 0% at 6,500 r. The proportion of normal embryonic development decreased from 46% at 45 r, to 12% at 500 r, to 0% at 6,500 r. In combination with data from a previous study of the irraiation of rabbit sper matozoa in vitro the following points are revealed: No abnormal fetus, no high proportion of degeneration after implantation, and no disturbance of the sex ratio were observed whether spermatozoa, or ova, unfertilized, or fertilized, were irradiated from 45 r to 800 r. Although there may be a differential sensitivity to various dosages for the subsequent cleavage and blastocyst formation following the irradiation of spermatozoa, unfertilized or fertilized ova at 45 r to 6,500 r, as far as subsequent embryonic development is concerned, the spermatozoa are more radioresistant than either unfertilized or fertilized ova and the unfertilized ova are more radiosensitive than fertilized ova. The chemical constituents of gametes necessary for the future development of the zygotes are more radiosensitive than are those for their fertilization and other activities.
- Research Organization:
- Worcester Foundation for Experimental Biology, Shrewsbury, Mass.; Boston Univ.
- NSA Number:
- NSA-13-009572
- OSTI ID:
- 4289087
- Journal Information:
- Anat. Record, Vol. Vol: 132; Other Information: Orig. Receipt Date: 31-DEC-59
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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