Fig. 2.

Phenotype of Jak2 G−/− male mice. Male puberty was assessed daily by preputial separation after 20 days of birth as previously described [56]. Male Jak2 G−/− mice were mated with proven fertile female mice for a period of 80 days. Time to each litter and litter size for each pair were recorded. a Preputial separation was examined as a measure of male puberty and the day of separation was documented and average values displayed. Significance is indicated. b Male mice mated with wild-type female for 80 days. Number of litters per male during 80 days of mating was reduced significantly in Jak2 G−/− mice compared to controls. c Number of pups per litter is not significantly different between Jak2 G−/− male mice and controls. For a–c, values are mean±SEM and significance and numbers of animals examined are indicated