CRYOPRESERVED HAMSTER EGGS FOR FERTILITY STUDIES

THIS PROPOSAL RELATES TO THE FEASIBILITY OF SUPEROVULATING 40-50 EGGS FROM THE PREPUBERTAL FEMALE SYRIAN HAMSTER (SH) AS A COST EFFECTIVE SOURCE OF QUALITY-ASSURED CRYOPRESERVED HAMSTER EGGS TO SERVICE THE NEEDS OF RESEARCH AND DIAGNOSTICLABORATORIES ENGAGED IN HUMAN MALE FERTILITY AND FUTURE GENERATION RISK ASSESSMENTS. THE DESIRED ENDPOINT, NAMELY, FAVORABLE CRYOGENICS AND RETENTION OF FERTILIZABILITY/SPERM PENETRABILITY FOLLOWING THAWING, WILL CENTER UPON THE ADAPTATION OF THE NORMAL-LIKE 78 HOUR PMS-HCG TIME INTERVAL TO ENCOURAGE SYNCHRONOUS NUCLEAR AND CYTOPLASMIC MATURATION.THE LATTER RELATIONSHIP WAS FOUND TO BE ESSENTIAL FOR ASSESSING MATERNAL CHROMOSOME NON-DISJUNCTION IN THE CHINESEHAMSTER (CH), IN RESPONSE TO TUBULIN-INTERACTING PROPERTIES OF TEST COMPOUNDS. IN THE ADULT FEMALE CH, THIS VITAL CONSIDERATION WAS SATISFIED BY SCHEDULING PMS AND HCG IN CONCERT WITH THE CORRESPONDING ENDOGENEOUS SURGES OF FOLLICLE-STIMULATING (FSH) AND LUTEINIZING (LH) HORMONES. WHEN THE 78 HOUR PMS-HCG TIME INTERVAL WAS APPLIED TO PREPUBERTAL CH AND SH, OPTIMAL SUPEROVULATION WAS READILY AND PREDICTABLY ATTAINED. PRELIMINARY EVALUATIONS SUGGEST THAT THIS PROCEDURE MAY READILY COMPENSATE FOR THE RESIDUAL IMMATURITY OF SUPEROVULATED EGGS DERIVED WITH TIME INTERVALSOF 48-56 HOURS. PHASE I ACTIVITIES WILL CENTER UPON: (A) CLARIFYING AGE, WEIGHT, AND HORMONAL DOSE RELATIONSHIPS OF 30-35 DAY OLD FEMALE SH; (B) ASSEMBLING THE "IN VITRO" FERTILIZATION/SPERM PENETRATION ASSAYS TO BEGIN GAINING THE NECESSARY PROFICIENCIES TO ASSESS CRYOGENIC PROCEDURES IN RELATION TO THE PERFORMANCE OF FROZEN-THAWED EGGS, PARTICULARLY DURING PHASE II, AND (C) RECOGNIZING STEPS (OR COMPONENTS) OF THE CURRENT MANUALLY-OPERATED PROCEDURES FOR CRYOPRESERVING HAMSTER EGGS FOR POSSIBLE ADAPTATION AND AUTOMATION. COMPARATIVE STUDIES WILL BE LIMITED TO EGGS SUPEROVULATED WITH THE 56 VS. 78 HOUR PMS-HCG TIME INTERVALSFOLLOWING SIMULTANEOUS HARVESTING, CRYOPRESERVING AND THAWING.