Elizabeth Steel

Changes in sensitivity of the canary brood patch during the natural breeding season

Abstract 1. 1. The tactile sensitivity of the brood patch of domesticated canaries was assessed at intervals through the natural breeding season. 2. 2. The tactile threshold fell as the season advanced. Both females which incubated their first eggs and those which did not showed a progressive fall in threshold around the time of egg-laying. 3. 3. The sensitivity-changes showed no close relationship to other criteria of reproductive development. Birds which laid early in the season showed little fall in threshold at the time of egg-laying: the later the various criteria of reproductive development appeared, the more had the threshold fallen. 4. 4. Large falls in threshold were especially likely to occur around days −1 −2 , −9 −10 and −18 −19 (with reference to egg-laying). In some individuals nest-building also showed indications of cyclicity. 5. 5. Males also showed some change in tactile sensitivity.

Effect of female odour on male hamsters mediated by the vomeronasal organ

A comparison was made of the response to female vaginal odour, between males that were intact (I), had an ablated vomeronasal epithelium (VNOX) or had the main olfactory epithelium destroyed by zinc sulphate lavage (ZN). I males, after exposure to vaginal odour, can subsequently discriminate between the donor of the odour and other, mismatching females. VNOX males are unable to discriminate. Peripherally anosmic males (ZN) could still discriminate mismatching females. Neither treatment affected the amount of sniffing directed at novel females. This confirms a previous study in which it was found that the non-volatile fraction of the female vaginal discharge is necessary for match/mismatch discrimination and that this is most likely to be sampled via the vomeronasal organ.

Effect of the odour of vaginal secretion on non-copulatory behaviour of male hamsters (Mesocricetus auratus)

Abstract Male hamsters were exposed to female vaginal secretion (in the absence of the female). When subsequently tested with females, their behaviour was determined by whether the test female matched or did not match the vaginal secretion. Less time was spent with mismatching females and less sniffing and licking was directed towards them. The effect of vaginal odour was present up to 3–4 h after the last contact with the secretion. The number of encounters with the vaginal odour and the spacing between them was important in determining the response to mismatching females. Contact with the vaginal secretion as opposed to its volatile components alone was necessary for the discrimination to occur. Discussion centres around the role of the vomeronasal organ and possible physiological pathways underlying the effect.

Male-female interaction throughout the oestrous cycle of the Syrian hamster (Mesocricetus auratus).

Interactions between male and female hamsters over the oestrous cycle were measured in terms of proximity. Independent variations in approaching and leaving by the female were found over the four-day period. Changes in female behaviour, which could be related to known changes in her hormonal state, resulted in changes in the male-female interaction not only at oestrous but also within the three dioestrous days of the cycle. These changes were in the amount of time the animals spent together or apart; this in turn was affected by which sex initiated the approaches and leaves. During oestrus proximity measures correlated well with latency to first lordosis which is a sensitive measure of degree of receptivity. Proximity measures provide a detailed description of the male-female interaction and should prove useful in studying the effects of experimental alteration of previous experience and hormonal state.

The aromatase inhibitor, 1,4,6-androstatriene-3,17-dione (ATD), blocks testosterone-induced olfactory behaviour in the hamster

The effect of ATD on olfactory investigation in intact and in castrated, testosterone-treated male hamsters was studied using subcutaneous silastic implants. In intact males, there was a dose-dependent action of ATD in reducing sniffing towards novel females and in eliminating the discrimination between females after pre-exposure to vaginal odour. Both sniffing and olfactory discrimination reappeared after removal of ATD implants. Neither the weight nor the general behavioural activity of treated males was affected, indicating a specific behavioural affect. Testosterone (T) maintained olfactory behaviour in castrated males. Untreated castrates and castrates with ATD + T implants showed reduced sniffing and showed no discrimination between females after exposure to female odour. We conclude that conversion of T to oestrogen plays an essential role in the control of male olfactory behaviour.

Female sexual behaviour: Roles of gonadal hormones in the syrian hamster

The sexual behaviour of ovariectomized female hamsters was examined after treatment with oestrogen alone and after the addition of progesterone. Both the proceptive and receptive components of behaviour were recorded at four oestrogen dose levels; progesterone dose was kept constant. Oestrogen alone caused dose-dependent increases in proceptive behaviour and, at the higher dose levels, a small increase in receptivity. The addition of progesterone increased proceptive behaviour in females primed with the lower dose of oestrogen but not the higher. Receptivity was markedly increased in all animals but the intensity of lordosis was oestrogen-dose dependent.