Light and the Timing of Ovulation in the Guinea-Pig

Donovan, B. T.; Lockhart, Andrew

doi:10.1530/jrf.0.0300207

Cited by 15 publications

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“…Our own attempts to use this technique for determining the right time to pair guinea-pigs were unsuccessful. Unsatisfactory results were also obtained by attempting to time ovulation by means of change of daylight (Dempsey, Myers, Young & Jennison, 1934;Donovan & Lockhart, 1972) or by inducing oestrus through administration of hormones (Dempsey, Hertz & Young, 1936;Ford & Young, 1951). The most common method presently in use takes advantage of the occurrence of oestrus post partum but it suffers from being slow and not completely reliable.…”

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Vaginal impedance measurement used for mating in the guinea-pig

Bartoš

Sedláček

1977

Lab Anim

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57Summary A method for determining the phase of the oestrous cycle by measuring the electrical impedance of the vaginal mucous membrane was examined in the guinea-pig. The apparatus consisted of silver ring electrodes attached to a plastic rod and connected to a transistor indicator.A cyclic increase in impedance was found, and significantly higher values were recorded during the phase of increase (proestrus) than at other times of the cycle. By determining this peak the right time for pairing can be chosen. Conversely, the disappearance of this cyclic culmination in impedance pointed to early pregnancy with a high degree of reliability.For some ontogenetic studies it is essential to have precise information on foetal age and for this reason it is important to be able to determine the day of mating. In the guinea-pig the use of vaginal cytology was first reported by Stockard & Papanicolau (1917); later references to this technique include those of Young, Myers & Dempsey (1933) and Hermreck & Greenwald (1964). Our own attempts to use this technique for determining the right time to pair guinea-pigs were unsuccessful. Unsatisfactory results were also obtained by attempting to time ovulation by means of change of daylight (Dempsey, Myers, Young & Jennison, 1934;Donovan & Lockhart, 1972) or by inducing oestrus through administration of hormones (Dempsey, Hertz & Young, 1936;Ford & Young, 1951). The most common method presently in use takes advantage of the occurrence of oestrus post partum but it suffers from being slow and not completely reliable. So far the best results have been obtained by measuring changes in electrical impedance of the vaginal mucous membrane, as described in the rat (Bartos, 1977). Our experience with this technique in the guinea-pig is described below. Materials and methodsThe electrical impedance of the vaginal mucous membrane (Elv.m.m.) was measured as described for the rat (Bartos, 1977), except that the distance between the ring electrod.:s was 6 mm.A total of 30 female guinea-pigs, aged I year, was used for the basic measurements, which were made once daily at about 0900 over 61 days. In the case of the ontogenetic experiment described by Sedlatek (1976) at proestrus was 3027 :1-170 n compared with a mean of 1041 ± 9 n for the other phases of the cycle; the difference is statistically significant (P

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