IRWIN I. OSTER 



Table 4. Results of the irradiation in the female of sperm obtained from males of different 



origin 



Males Per cent translocations 



y B(J 74/1547 = 4-8 



(Females) bw; st pP — — Oregon-R S 68/1528 = 4-5 



Samarkand $ 92/2114= 4-4 



On the other hand, it is possible that different physiological environments 

 in the seminal receptacles and spermathecae may result in different rates of 

 induced chromosome breakage in the spermatozoa stored in these organs. 

 Also variations in the ooplasm caused by different genotypes, environmental 

 influences on the females or both may result in different rates of chromosome 

 reunion. There should be ample opportunity for this to occur since it is 

 known that chromosomes broken in spermatozoa undergo reunion only after 

 fertilization*". To test this, sperm were X-rayed in females of different 

 genotype and phenotype and in various physiological conditions. Three 

 different wild-type stocks were selected. One of them in particular {i.e. the 

 Canton-S females) appeared to be more sensitive to the radiation-induced 

 necrosis following X irradiation of adults than the other two strains. The 

 lozenge stock was chosen since, unlike ordinary females which have both 

 spermathecae and seminal receptacles, this mutant besides having abnormally 

 shaped eyes lacks spermathecae for storing spermatozoa. The spermathecae are 

 a pair of mushroom-shaped organs 70 [x wide and 40 [x high, connected to the 

 uterus by a slender duct 145 [l long and 20 \l in diameter. In fertilized females 

 the lumen is filled with a concentrically coiled mass of spermatozoa. The 

 seminal receptacle is a compactly coiled tube applied to the anterior end of the 

 uterus, below the common oviduct. The tube is long ( 1 • 5 to 2 • 7 mm) and its 

 diameter is 2 -5 to 4-5 [x at its proximal portion and 12 to 19 [j. at its distal 

 part. In virgin females the receptacle contains a liquid, appearing in sections 

 as a reticular coagulum; after fertilization the lumen is filled with sperma- 

 tozoa, arranged longitudinally with their heads toward the tip of the tube. 

 It is possible that absence of one of these structures may influence X-ray 

 mutagenesis, for instance, by causing more crowding of the sperm in the 

 structure which is present. Starvation and desiccation for 12 hours prior to 

 irradiation in one group and in another followed by an exposure to a 100 

 per cent oxygen atmosphere for one hour after irradiation were also tried in 

 order to attempt to influence X-ray mutagenesis by altering the physio- 

 logical condition of the female. The results shown in Table 5 were obtained. 



Thus these variations, even if they do alter the milieu of the sperm in 

 inseminated females, are without effect on the mutagenic efficacy of X-rays 

 on mature male germ cells. These results can also be used as an indication 

 that if some pre-, simultaneous, or post-treatment is found to alter the 

 induced mutation rate of sperm exposed in females then it is at least not 

 mediated through such an indirect effect as starvation of the females, our 

 results having shown that such physiological changes do not have an ap- 

 preciable effect on X-ray mutagenesis in sperm of inseminated females. 



263 



