Effects of reduction of the number of primordial follicles on follicular development to achieve puberty in female rats

Abstract

was still smaller than in the controls. The concentration of serum immunoreactive inhibin of the offspring treated with busulfan was reduced on day 7 after birth without alteration of the concentration of gonadotrophin. On day 13 after birth, the concentration of serum immunoreactive inhibin was reduced only in the offspring treated with 5 mg busulfan kg −1 , and the concentration of serum FSH of the offspring was increased inversely as found on day 15 after birth. These results indicate that a reduction in the number of primordial follicles decreases the number of follicles that enter the growing phase, a major source of circulating inhibin in the neonatal and infantile ovary, and that consequently increased circulating FSH may accelerate follicular development to achieve puberty.

Reduction of Primordial Follicles Caused by Maternal Treatment with Busulfan Promotes Endometrial Adenocarcinoma Development in Donryu Rats

“…Inhibin is a regulatory peptide that inhibits FSH synthesis and release from the pituitary, resulting in regulation of ovulation in mammals [17,[27][28][29][30]. Previous studies have indicated that the concentration of inhibin reflects the number of primary and preantral follicles until antral follicle formation in the ovary [9,31]. Our results provide evidence that the hypothalmopituitary-gonadal control system still responds at 15 months of age after busulfan treatment.…”

“…number of growing follicles [8]. Shirota et al have demonstrated that the number of preantral follicles in the ovaries of Sprague-Dawley rats prenatally exposed to 2.5 mg/kg busulfan was comparable to the age-matched control value by day 13 after birth, and that the number of oocytes shed at the first ovulation with 5.0 mg/kg busulfan was also comparable to that in the controls [9]. In general, PE corresponds to an anovulation status, and appears in various situations such as neonatal exposure to high doses of estrogens and/or androgens and with aging in rodents, although the latter greatly varies depending on the strain [3, 4, 2 4 , 2 5 ] .…”

“…In addition, Shirota et al [9] have demonstrated that a reduction in the number of primordial follicles resulting in decrease in the number of follicles entering the growing phase, a major source of circulating inhibin in the neonatal and infantile ovary. A consequent elevation in circulating FSH may accelerate follicular development and cause early puberty in rats treated with busulfan maternally.…”

“…Busulfan was used as an agent since this chemical has been reported to reduce the number of oogonia during the period of germ cell proliferation and to consequently reduce the number of primordial follicles formed in the ovary in rats [8,9]. In addition, the endocrinological status of the treated rats was analyzed.…”

Expressing urine from a gel disposable diaper for biomonitoring using phthalates as an example

“…However, evidence from animal studies suggests that the fetal ovary may be more sensitive to these agents than the prepubertal or adult ovary. Fetal exposure to busulfan causes reduced numbers of oogonia and primordial follicles in rats (Merchant, 1975;Hirshfield, 1994), and high-dose exposure causes preterm ovarian exhaustion (Shirota et al, 2003). Also in humans, high-dose busulfan regimens cause ovarian failure in young women (Cicognani et al, 2003).…”