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RADIOSENSITIVITY OF DEVELOPING REPRODUCTIVE CELLS IN FEMALE COCHLIOMYIA HOMINIVORAX

1962; Oxford University Press; Volume: 47; Issue: 6 Linguagem: Inglês

10.1093/genetics/47.6.721

1943-2631

Leo E. LaChance, Ann P. Leverich,

Reproductive Biology and Fertility

In female Cochliomyia hominivorax, radiation-induced dominant lethal changes in the reproductive cells (which develop synchronously) were measured by egg-hatchability tests and correlated with cytological observations of the stage of nuclear development. In pupae 4 to 6 days olds only oogonial cells are present. Irradiation at this age reduced the number of mature oocytes produced as the dose increaseds but the lowered hatchability of eggs that were produced indicated that some dominant lethals persisted through maturation to be detectable in the embryo. In old pupae and newly eclosed adults, differentiation of the oocytes and nurse cells takes place. Irradiation of adults less than 24 hours old interfered considerably with egg production; the younger the female at irradiations the fewer normal eggs were produced. Irradiation of females older than 24 hours resulted in production of normal numbers of eggs. In three-day-old females the oocyte nucleus is in prophase I, in four-day-old females metaphase is and in five-day-old females anaphase I. Dosage-response studies indicated that the LD/sub 50/ radiation dose for oocytes in metaphase I is 1,309 r, anaphase I, 1,689 r, and prophase I, 7,989 r. For more » oocytes irradiated in the first meiotic divisions the relation between dose and dominant lethals induced was linear for the range investigated. (auth) C « less