Get Synchronization Of Adult Females For Timed Pregnancies - Rrrc

A timed pregnant female is a mouse or rat with a precisely known mating date.

Female and male mice are obtained and put into separate cages where they are raised. A few days before mating is to begin, male mice will be kept individually (1 mouse per cage) and female mice will be kept in a herd (5 mice per cage).

Timed pregnancies (often referred as Time Preg, or TP) is a technique used with laboratory mice and rats to allow researchers to harvest embryos at a specific gestational age. Simply put, timed pregnancies are pregnancies where the conception date is precisely known.

The estrous cycle in female mice is typically 4-5 days long and is divided into four phases: proestrus, estrus, metestrus and diestrus. Females can only become pregnant when ovulation occurs (during estrus). Estrus lasts only about 15 hours, and ovulation usually occurs during the middle of the dark cycle.

Currently, producing pseudopregnant mice is done by estrus synchronization using progesterone treatment, with 63% of female mice having a vaginal plug after mating15.

Superfoetation can happen, but it's usually reserved for mice and rabbits. Getting pregnant while already pregnant is called superfoetation. It's been reported in mammals, including mice and rabbits, and there have been a handful of possible cases in humans.

The average gestation time for mice is 19 to 21 days. Baby mice are called pups and are born deaf and blind. The average litter size is 10 to 12 pups.

Timed pregnancies in mice can be set up in two ways: 1) use vaginal cytology to determine the stage of a mouse's estrous cycle and the appropriate time for mating; and/or 2) check females for vaginal plugs to determine if mating has occurred.