CONTINUOUS LUTEINIZING-HORMONE INFUSION PREVENTS ATRETIC CHANGES OF THE FOLLICLES DURING SUPEROVULATION IN HAMSTERS

Superovulation with exogenous gonadotropins has been used widely to st udy the reproductive events in animals and in vitro fertilization and embryo transfer in human beings. However, details of the mechanism of superovulation are not yet clearly understood. The present study was c onducted to study the mechanism of superovulation with purified human FSH and LH preparations. Cyclic hamsters received continuous infusion of purified FSH and LH for 4 days, from estrus to proestrus. The numbe r of ova shed was significantly increased by 5 iu FSH/minipump infusio n, and further increased by 5 iu FSH/minipump plus 5 iu LH/minipump gr oup. On the other hand, the number of atretic follicles was decreased significantly (P<0.01) by the combined infusion of FSH and LH, but not by FSH alone. Among these experimental groups, there was no significa nt difference in embryonic development which was assessed by the count ing of the number of 4-cells and more developed embryos on day 3 of pr egnancy. These data indicated the different roles of FSH and LH in the superovulation process, because FSH stimulated some small follicles t o grow and LH, in the presence of FSH, rescued the follicles to underg o atresia.