Fig. 3. Analysis of the spermatogenic block in CIT-K^-/- mice. (A-B) Expression of the indicated spermatogenic markers was analyzed by RT-PCR under semi-quantitative conditions. The assay was performed on total RNA extracted from CIT-K knockout (-) and littermate control (+) mice at P8 (A) and P14 (B). (C,D) Primordial germ cells were identified by alkaline phosphatase staining of comparable longitudinal sections of E12.5 CIT-K^+/+ (C) and ^-/- (D) embryonic testes. (E,F) Gonocytes and undifferentiated spermatogonia were identified on sections of P4 CIT-K^+/+ (E) and ^-/- (F) testes by anti-cyclinD1 immunostaining. (G) The total number of gonocytes and undifferentiated spermatogonia was determined on hematoxylin- and eosin-stained histological sections of testes from CIT-K^+/+ (open bars) and ^-/- (closed bars) mice at the indicated times. Values are expressed as a percentage of the control. Error bars are standard deviation, P<0.01.