Effects on embryonic development of X-irradiation of rabbit spermatozoain vitro

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Abstract
Rabbits in which ovulation was induced artificially by intravenous injn. of 50 I. U. chorionic gonadotrophin were inseminated with spermatozoa exposed in vitro to doses of X-rays varying from 50-100,000 r., the ova being examined grossly, under visual microscopy with hematoxylineosin and under ultraviolet microphotography. At 250 r.-l,000 r., the normal divisions dropped progressively below the normal of 80-90% down to 2% independently of intensity or type of irradiation and time of irradiation before insemination (5-17 hrs.). Entry of spermatozoa into ova was effected at all dose levels. Cytological damage to the spermatozoa nucleus, appeared at 10,000 r., polyspermy appeared at 1,000 r. Activation occurred at all levels, but syngamy became irregular at 10,000 r. with suppression of spindle fibre formation at higher dosages. Occasional haploid and triploid ova were observed at the one-cell stage, but not in divided ova, and there was no continued gynogenetic development. From 50-250 r., normal fertile young were born. At 500 r., incidence of pregnancy and litter size were reduced, young were less viable, but survivors were normally fertile. No implanted embryos, fetuses or living young were obtained from spermatozoa exposed to 1,000 r. or over.