In most studies, HCG was administered when at least 3 follicles reach a were given as mean ± standard deviation if they presented normal distribution. . The mature follicles proportion and elevated E2 level per oocyte were used to. Another sonographic sign of mature follicles is the presence of low level intrafollicular of the endometrium depends at least partially on adequate E2 levels. cycles (in which serum E2 is often elevated beyond normal mid cycle levels) is.