Ovarian follicles

Abstract: Menopause is the permanent cessation of menstruation resulting from loss of ovarian follicular activity which happens as a result of depletion of primary follicles which is basically an aging effect. Depletion of ovarian follicles is reflected as declined production of oestradiol which is currently known to be central to the morphologic and physiological changes that happen during the climacteric, menopause and post menopause periods. The cessation of oestradiol production is much more pronounced in tissues with oestrogen receptors such as bones, brain, blood vessels, central nervous system and the skin. But generally little is known on the subject and in particular the bioactive substances involved in the process such that there are some symptoms that menopause women experience which not only defy clinicians but also challenge the management of the condition. This article is presented to shade light to what is currently known, what is not known and stimulate future resear...

Context: The possible toxic effects of monosodium glutamate (MSG) on ovarian functions have not been thoroughly evaluated in contrast to testicular functions. Few studies documented that MSG showed histological alterations.

Aims: To investigate the subacute effects of oral MSG (2 g/kg) on estrogen level and numbers of ovulated oocytes and histological changes in ovary of Sprague-Dawley (SD) rats.

Methods: Virgin young adult SD female rats with a regular estrous cycle were randomly assigned to either MSG-treated group or control group, and the duration of treatment was 14-16 days for oral administration MSG or vehicle (distilled water), respectively.

Results: Oral MSG treatment with doses of 2 g/kg/day showed significantly (p<0.01) reduced numbers of ovulated oocytes in the oviduct, newly formed corpora lutea, large follicles in histology of ovarian sections and attenuated serum estrogen levels.

Conclusions: Subacute oral administration of MSG may negatively influence the ovarian function of young female rats via reduction of ovulated oocytes and the attenuation of estrogen level.

Repeated dosing with the occupational chemical 4-vinylcyclohexene diepoxide (VCD) selectively depletes small pre-antral follicles in the ovaries of rats and mice via apoptosis. The aryl hydrocarbon receptor (AhR) plays a role in mediating the effects of several xenobiotics. Therefore, this study was designed to investigate a potential role of the AhR in VCD-induced ovotoxicity. Female F344 rats, C57BL/6 mice, or AhR-deficient (-/-, AhRKO) mice were dosed daily (15 days) with vehicle, VCD (80 mg/kg, i.p.) and/or the AhR antagonist, alpha-naphthoflavone (ANF; 80 mg/kg, i.p.). Compared with controls, VCD caused a 60% reduction (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) in primordial and primary follicles in mice and rats. Concurrent dosing with ANF protected against the VCD-induced follicle loss in rats, but not in mice. As with AhR-intact mice and rats, VCD induced a 70% loss (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) of small pre-antral follicles in AhRKO mice. AhR mRNA expression was increased (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) by VCD dosing in small pre-antral follicles isolated from ovaries of rats but not mice. AhR protein in rats was increased by VCD dosing in oocyte nuclei in primordial and primary follicles when measured by immunofluorescence and confocal microscopy. In rat small pre-antral follicles, apoptosis-associated caspase-3-like activity was increased (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) by VCD treatment, decreased (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) by ANF treatment, and unaffected by VCD plus ANF treatment. VCD had no effect on expression of GST Ya1 or GST Ya2 mRNA or CYP 1A1 protein in rats. Taken together, these findings demonstrate a difference between rats and mice in the potential involvement of AhR as related to VCD-induced ovotoxicity. Whereas, AhR appears to be involved in rats, no evidence for a similar role in mice was obtained. Overall, these findings point out that there can be mechanistic species differences in ovarian responses to xenobiotic chemicals.

Repeated dosing of rats with the ovotoxic chemical, 4-vinylcyclohexene diepoxide (VCD), destroys primordial and primary ovarian follicles via apoptosis (physiological cell death) by accelerating the normal rate of atresia. The present study investigated the effect of a single dose (1x) of VCD. Immature (d28) female Fischer 344 rats were dosed 1x or 15x with VCD (80 mg/kg ip). Ovaries were collected 24 h or 15 days following 1x VCD or after 15x for classification and evaluation. Following 1x VCD the number of healthy primary follicles was greater (p &amp;lt; 0.05) than control 24 h and 15 days later. This effect reflected a slowing of the normal rate of atresia seen in control ovaries. There was no effect of a single dose on primordial or growing follicles at any time. Expression of mRNA encoding the cell death gene bax was reduced (p &amp;lt; 0.05) on d1 after 1x VCD in isolated primordial and primary follicles. These observations were in contrast to a decreased (p &amp;lt; 0. 05) number of healthy primary and primordial follicles in ovaries and increased (p &amp;lt; 0.05) bax mRNA in isolated follicles from rats dosed 15x for 15 days. Immunofluorescence staining revealed that, the distribution of Bax protein was similar between ovaries from controls and 1x or 15x VCD-treated rats. These data provide evidence for a &amp;quot;protective&amp;quot; response against the normal rate of atresia in primary ovarian follicles following exposure to 1x VCD. Additionally, changes in expression of bax mRNA paralleled alterations in the rate of atresia.

Repeated dosing of rats with the ovotoxic chemical, 4-vinylcyclohexene diepoxide (VCD), destroys primordial and primary ovarian follicles via apoptosis (physiological cell death) by accelerating the normal rate of atresia. The present study investigated the effect of a single dose (1x) of VCD. Immature (d28) female Fischer 344 rats were dosed 1x or 15x with VCD (80 mg/kg ip). Ovaries were collected 24 h or 15 days following 1x VCD or after 15x for classification and evaluation. Following 1x VCD the number of healthy primary follicles was greater (p &amp;lt; 0.05) than control 24 h and 15 days later. This effect reflected a slowing of the normal rate of atresia seen in control ovaries. There was no effect of a single dose on primordial or growing follicles at any time. Expression of mRNA encoding the cell death gene bax was reduced (p &amp;lt; 0.05) on d1 after 1x VCD in isolated primordial and primary follicles. These observations were in contrast to a decreased (p &amp;lt; 0. 05) number of healthy primary and primordial follicles in ovaries and increased (p &amp;lt; 0.05) bax mRNA in isolated follicles from rats dosed 15x for 15 days. Immunofluorescence staining revealed that, the distribution of Bax protein was similar between ovaries from controls and 1x or 15x VCD-treated rats. These data provide evidence for a &amp;quot;protective&amp;quot; response against the normal rate of atresia in primary ovarian follicles following exposure to 1x VCD. Additionally, changes in expression of bax mRNA paralleled alterations in the rate of atresia.

Repeated dosing with the occupational chemical 4-vinylcyclohexene diepoxide (VCD) selectively depletes small pre-antral follicles in the ovaries of rats and mice via apoptosis. The aryl hydrocarbon receptor (AhR) plays a role in mediating the effects of several xenobiotics. Therefore, this study was designed to investigate a potential role of the AhR in VCD-induced ovotoxicity. Female F344 rats, C57BL/6 mice, or

The inhibins are dimeric protein hormones produced by developing ovarian follicles that in many species inhibit the secretion of follicle-stimulating hormone (FSH) from pitu-itary gonadotropes (Woodruff et al. 1988). Inhibin A and inhibin B share a common α-subunit that assembles ...

Background: Many attempts have done to improve cryopreservation of mammalian ovaries using simple, economical and efficient technique “vitrification”. Objective: The aim of the present study was to compare the mouse ovaries cryopreservation by direct cover vitrification (DCV) using different concentrations of ethylene glycol (EG) with conventional vitrification methods (CV). Materials and Methods: Ninety NMRI mice were sacrificed by cervical dislocation; their ovaries were divided into three main experimental groups: control or non-vitrified group, CV group and DCV groups with 4, 6 and 8M EG as cryoprotectant. After vitrification-warming, the viability of mechanically isolated follicles and the morphology of ovarian follicles by light and electron microscopes were studied. Results: The normality of primary and preantral follicles in non-vitrified and CV groups were higher than those achieved by DCV groups (p&lt;0.001). The survival rates of isolated follicles in non-vitrified, CV an...