Acrosomal status of mouse spermatozoa in the oviductal isthmus

7 p.-7 fig.-1 tab.The principal purpose of this study was to establish the acrosomal status of mousespermatozoa stored in the isthmus of the oviduct after natural mating. Scanning electron micros-copy of oviducts fixed about 6 hr before the estimated ovulation time showed numerousacrosome-intact spermatozoa attached to the mucosal surface of the oviduct, or trapped inthe oviductal crypts. Nevertheless, an unambiguous assessment of the state of the acrosomerequires transmission electron microscopy. Using this method, it was observed that theacrosome was intact in the 81% of spermatozoa attached to the mucosal surface but in only31% of spermatozoa that were free in the lumen. Most of the free spermatozoa showed swell-ing or disruption of the acrosome. This result might indicate that the in vivo spermatozoon-oviductal mucosa interaction maintains the acrosome intact. Alternatively, it could mean thatonly ejaculated spermatozoa with a normal acrosome can establish such a mucosal relation-ship.This workwas partially supported by grant PB93-0117 from DGICYT (Spain)Peer reviewe