Appearance and number of follicles and change in the concentration of serum FSH in female bovine fetuses

Tanaka, Yoshinobu; Nakada, Ken; Moriyoshi, Masaharu; Sawamukai, Yutaka

doi:10.1530/rep.0.1210777

Cited by 59 publications

(42 citation statements)

References 13 publications

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“…In rats follicle assembly occurs starting on the day of birth and is mostly complete by 5 days of age, although un-assembled oocytes are sometimes detected at 10 days. In humans and cattle follicle assembly occurs in mid-gestation [1], [18], [19], [20], [21], [22].…”

Section: Introductionmentioning

confidence: 99%

Inhibitory Actions of Anti-Müllerian Hormone (AMH) on Ovarian Primordial Follicle Assembly

et al. 2011

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The current study was designed to investigate the actions of Anti-Müllerian Hormone (AMH) on primordial follicle assembly. Ovarian primordial follicles develop from the breakdown of oocyte nests during fetal development for the human and immediately after birth in rodents. AMH was found to inhibit primordial follicle assembly and decrease the initial primordial follicle pool size in a rat ovarian organ culture. The AMH expression was found to be primarily in the stromal tissue of the ovaries at this period of development, suggesting a stromal-epithelial cell interaction for primordial follicle assembly. AMH was found to promote alterations in the ovarian transcriptome during primordial follicle assembly with over 200 genes with altered expression. A gene network was identified suggesting a potential central role for the Fgf2/Nudt6 antisense transcript in the follicle assembly process. A number of signal transduction pathways are regulated by AMH actions on the ovarian transcriptome, in particular the transforming growth factor – beta (TGFß) signaling process. AMH is the first hormone/protein shown to have an inhibitory action on primordial follicle assembly. Due to the critical role of the primordial follicle pool size for female reproduction, elucidation of factors, such as AMH, that regulate the assembly process will provide insights into potential therapeutics to manipulate the pool size and female reproduction.

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Section: Introductionmentioning

confidence: 99%

Inhibitory Actions of Anti-Müllerian Hormone (AMH) on Ovarian Primordial Follicle Assembly

et al. 2011

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“…The establishment of the pool of primordial follicles is critical to a female's reproductive success, but very little is known about how this important developmental process is regulated. There is a remarkable lack of consistency in the literature on when primordial, primary and secondary follicles first appear in fetal bovine ovaries (Erickson 1966; Rüsse 1983; Dominguez et al 1988; Tanaka et al 2001). In light of these conflicting reports on the timing of follicular formation and development, we re-examined this question as a prelude to studies on the regulation of follicle assembly and the earliest stages of follicular development (Yang and Fortune 2008).…”

Section: Introductionmentioning

confidence: 99%

In vitro and in vivo regulation of follicular formation and activation in cattle

Fortune

Yang

Muruvi

2011

Reprod. Fertil. Dev.

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The establishment of a stockpile of non-growing, primordial follicles and its gradual depletion through activation of primordial follicles are essential processes for female fertility. However, the mechanisms that regulate follicle formation, the activation of primordial follicles to begin growth and the primary-to-secondary follicle transition are poorly understood, especially in domestic animals and primates. The authors’ laboratory is engaged in studying early stages of follicular development in cattle and this review summarises the progress to date. Bovine follicles begin to form in fetal ovaries around the beginning of the second trimester of pregnancy (about Day 90), but the first activated, primary follicles do not appear until after Day 140. Bovine fetal ovaries produce steroids and production is highest during the first trimester. In vitro, oestradiol and progesterone inhibit follicle formation and acquisition by newly formed follicles of the capacity to activate. Meiotic arrest of the oocyte in the diplotene stage of first prophase does not occur until after follicle formation and is correlated with acquisition of the capacity to activate. This may explain the gap between follicle formation and appearance of the first activated follicles. Once capacity to activate has been acquired, it seems likely that activation in vivo is controlled by the balance between stimulators and inhibitors of activation. Insulin and kit ligand stimulate and anti-Müllerian hormone (AMH) inhibits activation in vitro. Few bovine follicles transition from the primary to the secondary stage in vitro, but this transition is increased by medium supplements, testosterone and vascular endothelial growth factor (VEGF).

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“…1B). For example, Russe (1983) first detected these stages at 90, 140, and 210 d of gestation, respectively, whereas the estimates of Tanaka et al (2001) were quite different (i.e., 74, 91, and 120 d, respectively) and those of Burkhart et al (2010) were more similar (110, 130, and 150 d) to data of Russe (Fig. 1B).…”

Section: When Do Bovine Folicles Form?mentioning

confidence: 85%

“…Since gonadotropins have been detected in the fetal bovine circulation (Challis et al, 1974; Tanaka et al, 2001) and fetal ovaries have binding sites for FSH and LH (Wandji et al, 1992), we hypothesized that LH stimulates production of progesterone and androgens and that FSH stimulates the conversion of aromatizable androgens to estradiol. To test these hypotheses, ovaries obtained on d 80 to 89 of gestation (i.e., when steroid production is still fairly robust and just before follicle formation begins) were cut into pieces and the pieces were distributed to culture wells at random (2 pieces per well).…”

Section: Regulation Of Fetal Bovine Steroidogenesismentioning

confidence: 99%

“…(A) Timing of meiotic prophase I and formation of primordial follicles during pregnancy and early postnatal life in mice [adapted from Borum (1961)] and (B) reported times of first appearance of primordial, primary, and secondary follicles in fetal ovaries of humans [(van Wagenen and Simpson, 1965), sheep (McNatty et al, 1995), and cattle ( a Tanaka et al, 2001; b Russe, 1983; c Yang and Fortune, 2008; d Burkhart et al, 2010)].…”

Section: Figurementioning

confidence: 99%

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TRIENNIAL REPRODUCTION SYMPOSIUM: The ovarian follicular reserve in cattle: What regulates its formation and size?1,2

Fortune

Yang

Allen

et al. 2013

Journal of Animal Science

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The ovarian follicular reserve has been linked to fertility in cattle. Young adult cattle with low vs. high numbers of antral follicles ≥ 3 mm in diameter in follicular waves also have fewer preantral follicles and decreased fertility. This underscores the importance of understanding the factors that regulate early follicular development and establish the ovarian follicular reserve, but little is known about how the follicular reserve is first established. In ruminants and humans, follicles form during fetal life, but there is a gap (about 50 d in cattle) between the appearance of the first primordial follicles and the first growing, primary follicles. In this review we present evidence that in cattle, fetal ovarian steroids (i.e., estradiol and progesterone) are negative regulators of both follicle formation and of the acquisition by newly formed follicles of the capacity to activate (i.e., initiate growth). The results indicate that capacity to activate is linked to the completion of meiotic prophase I by the oocyte. The inhibitory effects of estradiol on follicle activation were found to be reversible and correlated with inhibition of the progression of meiotic prophase I. Fetal bovine ovaries produce steroid hormones and production varies considerably during gestation and in a pattern consistent with the hypothesis that they inhibit follicle formation and capacity of newly formed follicles to activate in vivo. However, little was known about how steroid production is regulated. In our studies, both LH and FSH stimulated progesterone and estradiol production by ovarian pieces in vitro. The addition of testosterone to the culture medium enhanced estradiol production, especially when FSH was also present, but inhibited progesterone production, even in the presence of gonadotropins. Evidence is also presented for effects of maternal nutrition and health and for potential effects of estrogenic endocrine-disrupting chemicals on the size of the ovarian follicular reserve established during fetal life. In summary, fetal ovarian steroids may be important regulators of the early stages of follicular development in cattle. Therefore, external factors that alter steroid production or action may affect the size of the ovarian follicular reserve.

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Appearance and number of follicles and change in the concentration of serum FSH in female bovine fetuses

Cited by 59 publications

References 13 publications

Inhibitory Actions of Anti-Müllerian Hormone (AMH) on Ovarian Primordial Follicle Assembly

Inhibitory Actions of Anti-Müllerian Hormone (AMH) on Ovarian Primordial Follicle Assembly

In vitro and in vivo regulation of follicular formation and activation in cattle

TRIENNIAL REPRODUCTION SYMPOSIUM: The ovarian follicular reserve in cattle: What regulates its formation and size?1,2

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