Figure 5

Morphology (left panel) and percent (right panel) of atretic follicles. Follicles were exhibiting histologic evidence of atresia (pyknotic, unadhered granulosa cells in the antrum; left panel) following administration of the hCG bolus in COS protocols in rhesus monkeys. Although relatively few (<10%) appear atretic prior to hCG injection (0 hr; small number below bar indicates sample size), the number increases significantly by 36 hrs post-hCG (40%; controls, CTRL). Moreover, the percentage of atretic follicles was influenced by the steroid milieu, since administration of a steroid synthesis inhibitor (trilostane, TRL) produced a cohort of 70% atretic follicles and co-administration of a progestin (R5020) reduced the percentage to pretreatment (0 hr hCG) levels of 10%. Thus, oocytes collected prior to follicle rupture could originate from degenerating, as well as healthy (i.e., luteinizing, ovulatory) follicles. See ref [59] for further details, including statistical (X²) analyses. Different letters above bars indicate significant differences over time within controls (CTRL; hCG alone). Asterisk, or NS indicate significant or nonsignificant differences between treatment groups at one timepoint.