The uterine eggs of Bufo japonicus are invested with four jelly layers, J1, J2, J3, and J4, from inner to outer, respectively. When eggs were inseminated with serially diluted sperm suspensions, a higher concentration of sperm was required for successful fertilization of dejellied uterine eggs in solubilized jelly preparation than fertilization of fully jellied uterine eggs. When the eggs taken from different portions of oviduct were inseminated, the eggs invested with J1J2J3 were fertilized as effectively as fully jellied uterine eggs. Those with J1J2 were fertilized at lower frequency but those with J1 and a thin J2 were hardly fertilizable. Eggs artificially invested with J3J4 were less fertilizable than the J1J2 eggs, but addition of J3J4 to J1 and a thin J2 made eggs as fertilizable as the J1J2 eggs. Observations on the sperm penetrating the jelly indicated that these differences in fertilizability were dependent on two variables: an increased number of sperm penetrating into J3 and J4, and an increased rate of acrosome reacted sperm in J1 and J2. © 1993 Wiley‐Liss, Inc.
ASJC Scopus subject areas