premature stage 0.60000002384185791016 6.0 true MmusDv:0000112 Mouse developmental stage that covers the period from P4 starting at TS28 until 5 weeks old. infant stage mouse_developmental_stage It is commonly accepted that mouse reaches sexual maturity by six weeks of age (see http://www.ahc.umn.edu/rar/breeding.html). We start this stage at P4 because TS27 'newborn' stage is not defined as a postnatal stage. 4-6 days 1-week-old stage 2-week-old stage 21-day-old stage 22-day-old stage 23-day-old stage 24-day-old stage 25-day-old stage 26-day-old stage 27-day-old stage 4-week-old stage 5-week-old stage