Fig. 3. Expression of Alrp in mice from postnatal days 13-29. Testis samples from two animals were prepared for each listed day. Samples (20 µg) of protein were separated in a 4 % to 12 % gradient gel. The respective western blots were probed with antibodies specific for mammalian Alrp, mouse cyritestin and actin. Alrp is detectable at the earliest stages of spermatogenesis examined. The largest amounts of Alrp are observed at days 13, 19, 25 and 29. In contrast, cyritestin is expressed during the later stages of spermatogenesis. The molecular masses (MW) of marker proteins and of cyritestin (110kDa) and actin (42kDa) are listed.