Archive for the ‘Mating’ Category

Timing of Mating, Sperm Dynamics: DISCUSSION(8)

Male capture rates remained relatively high until Day 21 of the rut (26 August), after which time male trapping rate declined significantly. A similar pattern of increased male activity later in the rut was obtained by radio-tracking studies and was shown to be associated primarily with movements between communal nests possibly in an effort to obtain mating opportunities. Trapping and radio-tracking data collected by Lazenby-Cohen and Cockburn suggest that mating in the agile Antechinus occurs in selected communal nest trees and that the mating system used by this species is that of lek promiscuity. No evidence was obtained in the present study to support or refute this theory. birth control yasmin

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Timing of Mating, Sperm Dynamics: DISCUSSION(7)

DISCUSSION(7)

This supports radio-tracking data collected by Lazenby-Cohen and Cockburn from a female on Day 18 after the commencement of the rut; these data indicated that this female was not visiting male nest trees at this time and had significantly reduced her foraging range from that observed early (Day 7) in the mating period. Together, these data strongly suggest that the 3 females radio-tracked by Lazenby-Cohen and Cockburn early and late in the rut were not receptive at the times they were being followed and that the 2 females followed on Day 18 of the rut had probably already mated and ovulated. buy flovent inhaler

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Timing of Mating, Sperm Dynamics: DISCUSSION(6)

One explanation for this might be that the duration of sperm storage in female agile Antechinus is related to the likelihood that an estrous female will encounter a male to inseminate her prior to ovulation. Hence, in a population of high density where the likelihood of encountering a male during estrus is great, lengthy periods of sperm storage may not be necessary. In contrast, in populations of low density, extended periods of estrus and sperm storage may be essential in order to ensure that females encounter mates prior to the annual male die-off. Further study is required to test this hypothesis. Evidence from captive studies indicates that spermatozoa stored in the isthmus of the oviduct are viable for extended periods, although the number and fertility of sperm stored decline significantly after —10 days. buy yasmin online

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Timing of Mating, Sperm Dynamics: DISCUSSION(5)

DISCUSSION(5)

Much has been made of laboratory studies showing that female Antechinus have the ability to store spermatozoa for extended periods (up to 2 wk) in the lower isthmus of the oviduct prior to ovulation. It was interesting to note, therefore, that the peak in the number of mated females caught (55%) and the ovulation date for 67% of all ovulated females sampled from the Powelltown population occurred at the same time (Day 14/15 of the rut, 1920 August) and corresponded exactly with the only occasion during the rut when the female trapping rate peaked and exceeded that of the males. buy ventolin inhalers

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Timing of Mating, Sperm Dynamics: DISCUSSION(4)

In captivity, females will usually mate a number of times during estrus. Captive females that have mated twice to completion typically have between 40 and 75 X 103 spermatozoa per side. In the reproductive tracts of 8 of the 11 mated females (—73%) caught in this study, less than 30 X 103 spermatozoa per side were recovered, suggesting that these females had mated only once prior to capture. Of these, 4 females had 10 X 103 or fewer spermatozoa per side, suggesting that they may not have been fully receptive when mating occurred, resulting in an early dismount, or else that mating had been interrupted. Three females, however, had between 45 and 75 X 103 spermatozoa per side, suggesting from captive studies that they had mated more than once prior to capture. buy cipro

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Timing of Mating, Sperm Dynamics: DISCUSSION(3)

DISCUSSION(3)

No other field data are available on length of copulation in this species. However, recent captive mating trials, both with and without competing males, showed that ejaculation in this species occurs sometime between the first and third hour of mating, adding further weight to the argument for the existence of lengthy copulations in the wild in this species. flovent inhaler

In captive and wild populations of the agile Antechinus, sperm production is restricted to a brief period prior to the mating season, and the epididymis has limited capacity for sperm storage. The continual loss of spermatozoa via spermatorrhoea observed in captive studies, even in unmated males, further depletes sperm reserves. It has been suggested, therefore, that few sperm (~3.5 X 106 spermatozoa per side) are available for mating at the commencement of the rut and even fewer remain at the conclusion of this period. This was confirmed in the present study, in which very low numbers of testicular and epididymal spermatozoa were found in males captured immediately after the rut.

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Timing of Mating, Sperm Dynamics: DISCUSSION(2)

Lazenby-Cohen and Cockburn also questioned the accuracy of Scott and Tan’s data and conclusions, suggesting that they were unaware that these animals nested communally and that mating probably also occurred in the nests. As a result, they suggested that Scott and Tan may have underestimated the probability that radioactive contamination may have influenced their results. buy birth control online

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