Increased secondary sex ratios in golden hamster litters sired by males without coagulating glands and seminal vesicles

In golden hamsters, although bilateral ablation of paternal coagulating glands (CGX) and seminal vesicles (SVX) did not affect fertility, a higher number of male pups were born. The present study aimed at determining whether this male-biased sex ratio was due to an imbalance of fertilization by X and Y chromosome-bearing sperms or whether it was the consequence of a sex-related differential survival of embryos. The sex of embryos sired by sham-operated (SH) controls or males subjected to bilateral ablation of ampullary glands (AGX), CGX and SVX was determined from chromosomal spreads at 10 h post coitum and 10 days post coitum. The primary sex ratio of of the SH group did not deviate from the hypothetical sex ratio of 1:1. The sex ratios of zygotes from the three experimental groups did not differ from that of the controls. However, by mid gestation, the sex ratio was significantly higher in the SVX group (P < 0.05) and the CGX group (P < 0.005). The absence of secretions from the ampullary gland, coagulating gland and seminal vesicle had no effect on the primary sex ratio, thus these glands did not appear to affect fertilization by the X and Y chromosome-bearing sperm. The increased secondary sex ratios observed in the SVX and CGX groups were due to the preferential survival of males.

Effect of bilateral auditory cortex lesions on sound localization in Japanese macaques

1. The ability of four Japanese macaques (Macaca fuscata) to localize sound was determined after bilateral ablation of auditory cortex. The animals were given two tests: a "midline" test in which they had to discriminate noise bursts presented from a loudspeaker located to the left from identical noise bursts presented from a loudspeaker located to the right of midline, and a "hemifield" test in which both loudspeakers were located in their right hemifield. 2. Both of the tests were administered by the use of two different behavioral tasks: a conditioned-avoidance task in which the animals were trained to make or break contact with a water spout to indicate the location of a sound source, and a two-choice task that required the animals to walk to the source of the sound. 3. The results of both the conditioned-avoidance and the two-choice tasks demonstrated that the animals were able to perform the midline discrimination although their localization acuity was reduced. However, the animals had great difficulty in learning to walk to the source of a sound in spite of the fact that they had received previous sound-localization training in the conditioned-avoidance task. This difficulty suggested that the monkeys no longer associated the sound with a location in space. 4. The results of both the conditioned-avoidance and the two-choice tasks demonstrated that the animals were unable to discriminate the locus of a sound source when both loudspeakers were located in the same hemifield. 5. Bilateral ablation of auditory cortex results in both sensory and perceptual deficits. The presence of sensory deficits is indicated by the decreased acuity in the left-right discrimination and the inability to discriminate between two loudspeakers located in the same hemifield. The deficit in the perception of the locus of sound is indicated by the difficulty in learning to approach the source of a sound, an ability which normal monkeys exhibit without training. 6. There appear to be species' differences in the effect of auditory cortex lesions on sound localization. Although cortical lesions result in a sound-localization deficit in several species of primates and carnivores, they have little or no effect on rats.