The stomach has three types of contractions: There are rhythmic, 3 per minute, synchronized contractions in the lower part of the stomach, which create waves of food particles and juice which splash against a closed sphincter muscle (the pyloric sphincter) to grind the food into small particles.
7 What is the gestation period, how many babies do they have, and when are they weaned? 1  The gestation period for rats is 19â22 days, for mice it is 17â21 days.  Rats and mice average 8â12 babies in a litter, but can have as few as 1 or as many as 20.
3. Expect litters within a month of mating since female mice go into estrus every 3 or 4 days and the gestation time of mice is 19-21 days.If no litters are produced after one month you should replace the mice that you are mating with your founder.. Expect litters within a month of mating since female mice go into estrus every 3 or 4 days and the gestation time of mice is 19-21 days.