Abstract: Chst14 gene-deleted homozygote mouse (Chst14 -/-) was expected as an animal model of musculocontractural Ehlers-Danlos syndrome (mcEDS).However, perinatal lethality made investigation using Chst14 -/-difficult.Then, we found that backcrossing to BALB/ c strain improved birth rate of Chst14 -/-(establishment of congenic strain: BALB.Chst14 -/-).However, the birth rate remains at a low level compared with Mendelian distribution.In this study, we examined whether environmental enrichment (EE) could improve the productivity of BALB.Chst14 -/-.BALB.Chst14 gene-deleted heterozygote breeding pairs were mated with or without EE which were set as control group (without EE), 3 groups using commercial EE (Shepherd Shack [SS group], Shepherd Tube [ST group], and Envirodri [ED group]), and 2 groups combining them (SS+ED group and ST+ED group).Pups of them were genotyped at 4 weeks age and birth rates were analyzed.The rates of Chst14 -/-of the litters were 5.4% in the control group, 11.0% in the SS group, 6.7% in the ST group, 7.4% in the ED group, 18.6% in the SS+ED group, and 7.4% in the ST+ED group.Significant difference was detected between the control group and the SS+ED group by Chi-squared test.These results suggest that appropriate EE can improve the birth rate of BALB.Chst14 -/-.Although there is empirical knowledge of menarche and menopause in non-human primates, there are few scientific reports.Therefore, we analyzed records of indoor-colony bred cynomolgus monkeys at the National Institutes of Biomedical Innovation, Health and Nutrition.Data from 74 cynomolgus monkeys were used for the analysis.We analyzed the time of menarche, stable menstruation, first pregnancy, and menopause.Life span was also examined.Menarche in cynomolgus monkeys occurred at 1,195 ± 209 days of age (3 years old).After the first menstrual period was confirmed, the weight continued to increase, and the animals did not show regular menstrual cycles, meaning physiological stability, until they were 1,490 ± 333 days old (4 years old), at intervals of 29.4 ± 4.3 days.Pregnancy was not confirmed until 2 years after menarche, at 1,987 ± 447 days of age (5 years old).The last menstruation was observed at 9,627 ± 1,169 days of age (26 years).Their life span was 11,693 ± 1,945 days old (32 years), indicating that they survived for approximately 6 years after menopause.Thus, it took two years from menarche to the confirmation of the first pregnancy, and it seemed necessary to distinguish and understand physical and mental maturation.Since the timing of the onset of these reproductive phenomena is the result of a complex mechanism with large individual differences, it seemed more appropriate to show each phenomenon as a period of time rather than a point in time.