User:AnjaAnderson/sandbox

This is my sandbox.

Species:
Many species which have been found to be induced ovulators and the reasons for this are not always clear. However, one possible reason is that induced ovulation could provide a better reporoductive potential for those species that typically have shorter life spans and less encounters resulting in lower mating opportunites throughout their lifetime.

Rodents such as ferrets, mice and rats are known induced ovulators. In Rats the East African Root Rat and the Cape-Dune, Natal, Highvield and Blind Mole Rats are known induced ovulators. These species require mating to stimulate the vagina and cervix, resulting in ovulation in the Females. The East African Root Rat has been found to have small spines on its penis which are also thought to contribute to this stimulation of induced ovulation.

Mice are also thought to be induced ovulators. Studies have found that the Lutenising Hormone (LH) is crucial to bring about the induced ovulation. Disruption in LH surges in the mice and knockout of the Progesterone receptor (progesterone is known to help maintain a pregnancy) results in lowered fertility of the mice.

The Koala species are a lesser known induced ovulatory. The Koalas require mating in which the presence of ejaculated semen is needed to stimulate the female to produce a LH surge (which would cause ovulation of a follicle). Unlike many other animals, simply being in the presence of a male koala is not enough to induce ovulation itself, and nor is vaginal stimulation on its own sufficient to cause induced ovulation to occur.

The presence of koala semen in female koalas is known to be able to cause induced ovulation on its own, however only in just under 50% of the subjects tested but statistical tests confirmed this to be significant.

Cats are another widely known induced ovulator. After mating, the LH levels in female cats surge and the time to ovulation can be predicted to occur between 1-2 days later.

Goats too have been found to be induced ovulators. A 1984 study saw LHRH injections were able to cause ovulation in goats that were of sexual maturity and already in oestrus. These injections had no influence on goats that were not in oestrus and could be because there is reduced sensitivity to LH and FSH receptors in the non oestrus stages of the cycle so the LHRH may not have been able to induce a great enough response.

Wolverines are other known induced ovulators which require physical mating to cause ovulation.

Horses are induced ovulators and studies using combinations of PGF2alpa analogues, Lipsostiol, d-cloprostenol and hCG were able to artificially induce ovulation in this species though these neural pathways.

Many bear species are able to have induced ovulation including the Grizzly bear, Black bear and the Polar bear where both the presence of a male and mating itself are requirements for induced ovulation. However, there are some suggestions that mating is not as strict a requirement in bears.

Black Bears are widely confirmed induced ovulators. It was observed that most females kept separate from males did not ovulate, where as females kept in areas with male bears did. Mating between the bears caused elevated progesterone levels and this was seen by increased progesterone levels measured in the bears in the months that followed the mating seasons. In black bears the presence of a males was enough to cause a notable rise in progesterone levels even without mating but mating. This could suggest that pheremonal/chemosensory factors could also contribute to induced ovulation in some species.

Induced ovulation is able to occur in some fish species. In china freshwater fish inclusing a variety of carp types, bream and loach are able to be induced to ovulate by using agonists of dopamine. This induction of ovulation from drugs is able to cause a predictable ovulation period and is very beneficial to farming of these species.