(A) Genotyping PCR confirmed insertion of the targeting vector between exon 2 and exon 4 in Hmmrtm1a/+ (Het) or Hmmrtm1a/tm1a (KO) but not in Hmmr+/+ (WT) mice. (B) HMMR expression in tissues extracted from WT, Het, or KO mice. Actin served as a loading control. (C) Weight at wean for WT and KO mice. Data are represented as mean ±SD (*p=0.028 (males), p=0.022 (females); for males, n = 10 (WT), 3 (KO); for females, n = 12 (WT), 4 (KO)). (D) Defects in seminiferous tubules are present in a KO male (*, atrophic tubules) relative to age-matched WT mouse stained with H&E. Scale bars, 200 µm. (E) Apoptosis (TUNEL staining) in KO male seminiferous tubules relative to age-matched WT mouse. Scale bars, 100 µm. (F) Number of litters per 6 months breeding time for matings of WT, Het, and KO mice. (*p<0.05; **p<0.01; n = 11 matings (WT x Het), 2 (Het x Het), 4 (WT x KO), 3 (Het x KO), 2 (KO x KO)). (G) Pups per litter for matings of WT, Het, and KO mice (See Figure 1F for n values). (H) Percentage of WT, Het, and KO pups at E14.5, E18.5 and weaning (~21 days) (***p<0.001; n = 64 (E14.5), 49 (E18.5), 133 (wean)). (I) Survival analysis for WT, Het or KO neonates during the first 48 hr following birth (n = 34 (WT), 69 (Het), 36 (KO)).