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PubMed2001

X-linked inhibitor of apoptosis protein activates the phosphatidylinositol 3-kinase/Akt pathway in rat granulosa cells during follicular development.

X-linked inhibitor of apoptosis protein (XIAP) in granulosa cells is regulated by gonadotropins during follicular development, although the current understanding of the mechanisms by which XIAP suppressed granulosa cell apoptosis is incomplete. In the present study, we investigated the possible involvement of the phosphatidylinositol 3-kinase (PI 3-K) survival pathway in the regulation of granulosa cell fate. Using a fully characterized in vivo model to study the induction of follicular development and atresia in immature rats, we have demonstrated that gonadotropin treatment increased granulosa cell XIAP and phospho-Akt protein contents and suppressed apoptosis. In addition, gonadotropin withdrawal [equine CG (eCG)-primed rats treated with an anti-eCG antibody] induced granulosa cell apoptosis and significantly decreased ovarian weight. The increased apoptosis was accompanied by marked decreases in XIAP expression and phosphorylation of Akt protein. Infection of granulosa cells from eCG-primed rats with adenoviral sense XIAP [lacZ as a control; multiplicity of infection, 1-5] resulted in XIAP overexpression and increased phospho-Akt content, whereas XIAP antisense expression (multiplicity of infection, 10-40) decreased granulosa cell phospho-Akt level and induced apoptosis. Addition of the specific PI 3-K inhibitor LY294002 to the granulosa cell cultures decreased Akt phosphorylation and induced apoptosis in a dose-dependent manner. Taken together, these results demonstrate for the first time the importance and regulation of the PI 3-K survival pathway by XIAP in the control granulosa cell apoptosis.

Animals↗
PubMed1987

Pharmacologic induction of multiple follicular development improves the success rate of artificial insemination with husband's semen in couples with male-related or unexplained infertility.

The use of artificial insemination with husband's semen (AIH) as treatment for couples with male-related or unexplained infertility is often disappointing. The aim of the present study was to evaluate whether the induction of multiple ovulation can increase the pregnancy rates in couples treated with AIH. Multiple follicular development was induced by means of clomiphene citrate (CC) plus purified follicle-stimulating hormone (FSH) in 17 couples undergoing AIH for male-related or unexplained infertility. In spite of the long duration of infertility (greater than 6 years), 10 couples (58.8%) achieved pregnancy within 6 months of treatment. This figure was significantly higher than that obtained in 120 couples who underwent AIH either during spontaneous cycles or after induction of follicular development with CC alone. These results suggest that the availability of multiple mature oocytes increases the conception rate during each cycle, as reported for in vitro fertilization (IVF) programs. It is therefore suggested that a trial of induction of multiple follicular development be performed in couples with male-related or unexplained infertility before their inclusion in protocols for invasive procedures, such as IVF or gamete intrafallopian transfer.

Clomiphene↗
PubMed2005

Ovarian response and follicular development for single-dose and multiple-dose protocols for gonadotropin-releasing hormone antagonist administration.

OBJECTIVE: To determine the efficiency of a single-dose and a multiple-dose protocol for GnRH antagonist administration. DESIGN: Randomized clinical trial. SETTING: University hospital, tertiary medical center. PATIENT(S): Sixty-one patients undergoing controlled ovarian stimulation (COS) and IVF/ICSI. INTERVENTION(S): COS with either a multiple-dose (MD) or a single-dose (SD) protocol for GnRH antagonist (cetrorelix) administration, or with a long protocol (LP) for GnRH agonist (buserelin) administration, followed by oocyte retrieval, IVF/ICSI, and embryo transfer. MAIN OUTCOME MEASURE(S): Follicular development and serum levels of E2 and LH. RESULT(S): The SD protocol for cetrorelix was associated with a more reduced level of follicular development, lower levels of serum estradiol on the day of HCG administration, and a more reduced number of zygotes than the LP for buserelin. The pregnancy and implantation rates did not differ significantly for the three study groups. CONCLUSION(S): The MD and SD GnRH antagonist protocols were effective for preventing LH surge and appear to elicit an equivalent pregnancy rate to that corresponding to a LP GnRH agonist. In terms of follicular development, the SD protocol requires further modification, including flexible scheduling or possibly a small reduction of the dosage of the administered cetrorelix.

Adult↗
PubMed1989

A comparison of the effects on follicular development between clomiphene citrate, its two separate isomers and spontaneous cycles.

An investigation of the effects on follicular development of clomiphene citrate and its two isomers En clomiphene and Zu clomiphene given separately was carried out on 19 normally cycling women being treated with donor insemination. All women received clomiphene citrate in the first cycle and, following a washout control cycle, were treated with either En clomiphene or Zu clomiphene alone. The number of follicles present, follicular phase oestrogen secretion and luteal phase pregnanediol excretion were not significantly different when Zu clomiphene cycles were compared with control cycles, but were significantly increased in En clomiphene and clomiphene citrate cycles. It is concluded that the En isomer, which has largely antioestrogenic properties, is the isomer active in inducing follicular development. The oestrogenic properties of Zu isomer did not appear to protect it from the possibly detrimental effects on sperm-cervical mucus interaction observed in both isomers and in the combined preparation.

Adult↗
PubMed1987

Effect of pulsatile infusion of gonadotropin-releasing hormone on plasma oestradiol-17 beta concentrations and follicular development during naturally and artificially maintained high levels of plasma progesterone in heifers.

To stimulate a follicular-phase pattern of pulsatile LH release, gonadotrophin-releasing hormone (GnRH; 5 micrograms) was infused (i.v.) hourly into heifers for periods of 5-11 days during the luteal phase of the oestrous cycle, and also when plasma progesterone levels were increased artificially by means of a progesterone-releasing intravaginal device. Plasma oestradiol-17 beta concentrations increased from basal (less than or equal to 2.5 pmol/l) to preovulatory peak levels (20-30 pmol/l) during the first 3 days of GnRH treatment. They were maintained at these values before returning to basal levels within 24 h of cessation of infusion. This response occurred regardless of the source of progesterone (endogenous or administered). Follicular development was observed by ovarian palpation (per rectum) in some heifers at the time of maximum secretion of oestradiol-17 beta. There was no detectable cervical mucus secretion or oestrous behaviour during these periods of high oestradiol-17 beta levels and ovulation did not occur. Treatment with GnRH did not affect plasma progesterone concentrations or oestrous cycle length. The study shows that oestradiol-17 beta secretion and follicular development (and the accompanying oestrus and ovulation) are suppressed during the luteal phase of the cycle by high concentrations of plasma progesterone, and provides strong indirect evidence that such inhibition is associated with a reduction in the pulse frequency of LH release.

Animals↗
PubMed1999

Genetic relationship among lines and smooth muscle and ovarian follicular development within lines of Japanese quail in two long-term selection studies.

Smooth muscle tumor and ovarian follicular development were studied in lines of Japanese quail selected for increased 4-wk BW (HW, P, and T) and their randombred controls (C and R1). The lines studied were from long-term selection studies at The Ohio State University (HW and R1) and The University of Georgia (P, T, and C). To study the genetic relationship among the lines in the two selection studies, the C, P, HW, and R1 lines were DNA-fingerprinted by digestion of the DNA with the HaeIII restriction enzyme and using Jeffreys' 33.6 probe. The BW of females at 4 wk of age and at the end of a 240-d egg production period were similar for the C and R1 lines. The BW of the selected lines was ranked P > T > HW for both measurements. Smooth muscle tumors were found in the oviducal ligaments adjacent to the magnum. A greater percentage of hens from the BW-selected lines had smooth muscle tumors of greater weight than the randombred control lines, which did not differ in tumor incidence or weight. The P and T lines had a greater incidence of multiple-lobed tumors than the HW line. Based on bandsharing (BS) of DNA fingerprints, the Georgia and Ohio lines did not appear to be closely related, suggesting that, perhaps, the smooth muscle tumors in the BW-selected lines in the two studies might have resulted from pleiotrophic effects of genes affecting growth or to genes closely linked to the growth genes. The BW-selected lines in both selection studies had more ovarian follicles in rapid development, which were of greater weight, than the randombred control lines. The HW line had a larger number of ovarian follicles in rapid development than the P and T lines. The percentage of hens with atretic follicles was greater in the BW-selected lines. The results of the present study suggest that the effect of BW selection on ovarian follicular development may occur early in selection (within the first 30 generations) and is not influenced by additional genetic changes in BW.

Animal Husbandry↗
PubMed2002

Regulated expression of Wnts and Frizzleds at specific stages of follicular development in the rodent ovary.

Wnt ligands and Frizzled (Fz) G protein-coupled receptors impact cell fate, including embryonic development of the ovary. Because the role of these regulatory molecules during follicular development in the adult is not known, an RT-PCR survey was done. Wnt-4, Fz-4, and Fz-1 were among the transcripts detected, and each exhibited a specific pattern of expression. Fz-1 mRNA was low in preovulatory follicles of PMSG-treated mice but was increased within 4-12 h after an ovulatory surge of human CG. By in situ analysis, Fz-1 transcripts increased first in the theca cells and then in the granulosa cells of ovulating follicles but were low in corpora lutea. In contrast, Wnt-4, a critical factor in early ovarian development, was expressed in small preantral follicles. In addition, Wnt-4 was detected in preovulatory follicles and exhibited high levels in corpora lutea. A potential receptor for Wnt-4 in corpora lutea is Fz-4 that was also elevated in this tissue. Although Wnt-4 has been shown to function downstream of the PR in other tissues, Wnt-4 was not altered in follicles of PR-null mice that fail to ovulate. Rather expression of Fz-1 was lower in ovaries of PR knockout mice, compared with normal littermates. Thus, specific Wnt/Fz are expressed at distinct stages of follicular development, suggesting multiple functions for this signaling pathway in the ovary.

Animals↗
PubMed1995

Growth hormone releasing factor and vasoactive intestinal peptide stimulate rat granulosa cell plasminogen activator activity in vitro during follicular development.

Growth hormone-releasing factor (GRF) and vasoactive intestinal peptide (VIP) are two structurally homologous peptides sharing common target cell receptor and known to enhance FSH-induced steroidogenesis of undifferentiated granulosa cell in vitro. Although VIP, has been reported to stimulate plasminogen activator (PA) activity in rat granulosa cells, our knowledge on the actions and interactions of these two peptides with FSH in the regulation of rat granulosa cell PA system during follicular development remains incomplete. Undifferentiated and differentiated rat granulosa cells from pre-antral (DES-treated rats) and antral (eCG-treated rats) follicles, respectively, were cultured in a chemically defined medium in the absence and presence of FSH (400 ng/ml), GRF (10(-8)-10(-5) M) and/or VIP (10(-9)-10(-5) M). Net secreted (PAs) and cell-associated (PAc) PA activities was measured by the fibrinolysis assay and characterized by the fibrin overlay method. Granulosa cell differentiative (progestin secretion) and proliferative (DNA synthesis) responses were analyzed by radioimmunoassay and [3H]thymidine incorporation, respectively. Both GRF and VIP stimulated PAs and PAc activities in a concentration-dependent manner in 24-h cultures of granulosa cells from the two stages of follicular development. They (10(-5) M) enhanced FSH-stimulated PAs activity in granulosa cell cultures of pre-antral follicles, with GRF being more effective than VIP. On the contrary, only GRF (10 microM) potentiated FSH-induced PAs and PAc activities in cultures of granulosa cell from antral follicles. The stimulation of PA activity by these agonists decreased with the duration of culture irrespective of the stage of follicular development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Ovarian sympathectomy in the guinea pig. II. Effects on follicular development during the prepubertal period and following exogenous gonadotropin stimulation.

The role of ovarian adrenergic nerves in follicular growth was studied in prepubertal guinea pigs by determining the effect of sympathectomy on follicle populations and follicular development following exogenous gonadotropin administration. Selective unilateral ovarian sympathectomy was achieved by injecting 6-hydroxydopamine into a surgically closed periovarian bursa on day 20 postpartum. The contralateral surgically closed ovarian bursa was injected with the vehicle used for 6-hydroxydopamine. On day 25, animals were injected with pregnant mare serum or saline followed by human chorionic gonadotropin or saline 48 h later. All animals were laparotomized on day 28 and blood from utero-ovarian veins was collected bilaterally for androstenedione determination. Ovaries were processed for morphometric analysis of follicles. The sympathectomized ovary in saline-injected animals had a significant decrease in preantral follicles (characterized by less than or equal to 2 layers of granulosa cells without antrum formation), an increase in 310-500 micron diameter atretic follicles and an increase in follicles greater than or equal to 700 micron compared to the contralateral control ovary. There were no differences in androstenedione levels from the two sides, ovarian weights or the total number of follicles per ovary. Neither ovary had corpora lutea. The sympathectomized ovary in animals injected with gonadotropins was not different from the contralateral ovary in any of the parameters measured. Both control and sympathectomized ovaries had newly formed corpora lutea in response to the exogenous gonadotropins. These results suggest that ovarian adrenergic nerves normally participate in follicular development in the prepubertal guinea pig. However, exogenous gonadotropins may override neural influences on the prepubertal ovary.

Androstenedione↗
PubMed2003

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

Effects of reduction of the number of primordial follicles on follicular development and concentrations of circulating hormones were examined in immature female rat offspring of dams given busulfan intraperitoneally on day 14 of gestation. The offspring of dams treated with 5 mg busulfan kg(-1) showed vaginal opening at an age comparable with the offspring of dams treated with 2.5 mg busulfan kg(-1) or with corn oil as a control, although they exhibited an irregular oestrous cycle until week 14 after birth. The serum concentrations of immunoreactive inhibin and FSH on day 26 after birth of the offspring treated with 5 mg busulfan kg(-1) were similar to those of age-matched controls. On day 15 after birth, however, the concentration of their immunoreactive inhibin was markedly lower than that of controls, whereas the concentration of their FSH was increased inversely. Comparison of the numbers of ovarian follicles in the controls and groups treated with 2.5 mg busulfan kg(-1) and 5 mg busulfan kg(-1) revealed that prenatal treatment with busulfan reduced the number of follicles in the primordial or primary phase and in the preantral phase on day 7 after birth. Although the increase of the ratio of the number of preantral follicles during days 7-13 after birth tended to vary with the prenatal dose of busulfan, the number of preantral follicles in the group treated with 5 mg busulfan kg(-1) 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.

Alkylating Agents↗
PubMed1998

Expression of inhibitor of apoptosis proteins (IAPs) in rat granulosa cells during ovarian follicular development and atresia.

The inhibitor of apoptosis proteins (IAPs) constitute a family of highly conserved apoptosis suppressor proteins that was originally identified in baculoviruses. Although IAP homologs have been recently identified and demonstrated to suppress apoptosis in mammalian cells, their expression and role during follicular development and atresia are unknown. The present study was conducted to address these questions. Using established in vivo models for the induction of follicular development and atresia in immature rats, it was possible to compare the immunolocalization of X-link inhibitor of apoptosis protein (Xiap) and human inhibitor of apoptosis protein-2 (Hiap-2), two members of the IAP family, at defined stages of follicular maturation and to relate the differences observed with those of follicular cell proliferation and apoptosis [as determined by proliferating cell nuclear antigen (PCNA) immunohistochemistry and in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL), respectively]. In addition, granulosa cell DNA and proteins were assessed for apoptotic fragmentation by 3'-end labeling/agarose gel electrophoresis (DNA ladder) and Hiap-2 and Xiap protein content by Western blot analysis, respectively. Hiap-2 and Xiap expression in both granulosa and theca cells increased with follicular maturation, reaching maximal levels at the antral stage of development. The immunoreactivity for PCNA, Xiap, and Hiap-2 decreased markedly in atretic (TUNEL-positive) follicles at the small to medium sized antral stage of development, suggesting follicular atresia may be associated with decreased granulosa cell IAP protein content and decreased proliferation. Atresia was also associated with a change in the intracellular distribution of IAPs in granulosa cells. Biochemical analysis of DNA fragmentation (DNA ladder) in granulosa cells from preantral and early antral follicles indicates extensive apoptosis that was associated with minimal IAP protein content. Gonadotropin treatment increased Hiap-2 and Xiap protein content and suppressed apoptosis in granulosa cells, resulting in the development of follicles to the antral and preovulatory stages. In addition, gonadotropin withdrawal induced apoptotic DNA fragmentation in granulosa cells in early antral and antral follicles, which is accompanied by a marked decrease in Hiap-2 and Xiap expression. These data suggest that IAPs may be involved in the suppression of granulosa cell apoptosis by gonadotropin in small to medium-sized antral follicles and play an important role in determining the fate of the cells, and thus also the eventual follicular destiny (atresia vs. ovulation).

Animals↗
PubMed1993

Interactions of transforming growth factor-alpha and -beta and luteinizing hormone in the regulation of plasminogen activator activity in avian granulosa cells during follicular development.

This study examined the influence of transforming growth factor-alpha (TGF alpha), TGF beta, and LH on progesterone (P4) secretion and plasminogen activator (PA) activity in cultured avian granulosa cells from the first (F1), third (F3), and fifth and sixth (F5-6) preovulatory follicles during a 21-h incubation period. PA activity in the cell (PAc) and the medium (PAm) fractions was measured by fibrinolysis and fibrin overlay methods. P4 was determined by RIA. Basal PAc and PAm activities were highest in cell cultures from the less mature (F5-6) follicles and decreased as follicles matured to the F1 stage of development. PAc activity was greater than PAm activity regardless of the stage of follicular maturation. TGF alpha (0.1-10 ng/ml) increased PA activity in cultures of granulosa cells from F1, F3, and F5-6 follicles in a concentration-dependent manner. TGF alpha-induced PAc and PAm activities were observed by 6 and 15 h of incubation, respectively, and increased rapidly between 15-21 h. LH (100 ng/ml) attenuated TGF alpha-induced PA activity by 15 h in cultures of granulosa cells from F1 and F3, but not F5-6, follicles. Basal PA activities were unaffected by the gonadotropin. TGF beta (2-100 ng/ml) stimulated PAc activity in a dose-dependent manner only in cultures of granulosa cells from F5-6 follicles and significantly enhanced TGF alpha-induced PAc and PAm activities in cell cultures from F3 and F5-6, but not F1, follicles. Basal and growth factor-induced PAc and PAm activities corresponded to a mol wt of about 35 kDa, a value consistent with that of the low mol wt uPA species. TGF alpha and TGF beta, alone or in combination, had no effect on basal P4 secretion at all stages of follicular development. TGF alpha, however, decreased LH-induced P4 secretion in F1 and F3 cultures. These results demonstrate a tightly controlled interaction of TGF alpha, TGF beta, and LH in regulating PA activity and P4 secretion during follicular development in the domestic hen.

Animals↗
PubMed1986

Follicular development after administration of adrenocorticotropin to nonlactating Holstein cows.

The effect of chronic administration of adrenocorticotropin on ovarian follicular development was studied. Twelve nonlactating Holstein cows received either 100 IU adrenocorticotropin (n = 6) or saline (n = 6) at 12-h intervals, commencing d 16 and continuing until d 23 of an induced estrous cycle (estrus = d 0). Cows were slaughtered on d 24, ovaries collected, and number of visible antral follicles recorded. Estradiol-17 beta, androstenedione, and testosterone in follicular fluid, and luteinizing hormone and follicle-stimulating hormone receptors in follicular tissue of the largest follicles were determined. Largest follicles were classified as ovulatory or nonovulatory based on the estrogen to androgen ratio. One cow treated with adrenocorticotropin, but none treated with saline, had ovulated by slaughter. The numbers of small, medium, and large antral follicles were 0, 1, and 5 for cows treated with adrenocorticotropin and 0, 1, and 6 for cows treated with saline. Follicular diameter (15.0 +/- 1.0 versus 14.0 +/- 2.0 mm) and follicular fluid volume (2.9 +/- .8 versus 2.2 +/- .5 ml) of the largest follicle in cows treated with adrenocorticotropin or saline were not different. No differences were found in the number of luteinizing hormone and follicle stimulating hormone receptors nor in the proportion of ovulatory versus nonovulatory follicles between treatments. We conclude that adrenocorticotropin administered at 100 IU every 12 h during the follicular phase does not significantly alter follicular development in the nonlactating dairy cow.

Adrenocorticotropic Hormone↗
PubMed1993

Follicular development and ovulation in the marmoset monkey as determined by repeated laparoscopic examination.

This paper describes the course of follicular development in vivo in the marmoset monkey, the only anthropoid primate with a relatively high (2-4) and variable ovulation number. Results are presented in relation to predictions from a mathematical model of control of follicle selection and ovulation number. Repeated laparoscopic examinations during the follicular phase were conducted for 14 cycles. Ovulatory follicles were 1.0 mm (median) in diameter at Day 6 and could be distinguished from nonovulatory follicles by Day 8, at which point they were 2.0 mm in diameter. Ovulations were not synchronous; the most common observation 1-2 days after the estradiol peak was ovulation of one follicle but not the other. Examination of the course of follicular development within a cycle and the distribution of ovulation sites both supported predictions stemming from a mathematical model of follicle selection developed by Lacker et al. [Biol Reprod 1987; 37:570-580]. Specific findings were the following: 1) Variations in patterns of follicle growth within a cycle resembled those generated by the model; in 64% of cycles, the 2-3 ovulatory follicles grew at similar rates. However, in 36% of cycles, ovulatory follicles displayed disparate rates of growth. 2) An examination of the distribution of ovulation sites (right versus left) revealed no significant difference from a binomial distribution, suggesting the likelihood that interovarian (rather than intraovarian) factors control this distribution.

Animals↗
PubMed1994

The effect of a GnRH analogue on the dynamics of follicular development and synchronization of estrus in lactating cyclic dairy cows.

A GnRH analogue was used to synchronize ovarian follicular development prior to an injection of PGF(2alpha) for the synchronization of estrus in lactating Holstein cows. On Day 12 (estrus = Day 0) of the experimental cycle, cows (n = 8) were injected with 8 mug Buserelin (BUS group), followed by 25 mg PGF(2alpha) 7 d later (Day 19). Control cows (n = 7) received PGF(2alpha) on Day 12 (PGF group). Ovaries were scanned daily via ultrasonography, and plasma progesterone and estradiol concentrations were determined. Sizes of all visible follicles were recorded. Follicles were classified as small (3 to 5 mm), medium (6 to 9 mm), or large (> or = 10 mm). Between Days 12 and 16 of the cycle, the number of large follicles in PGF cows remained unchanged (1.2), whereas in the BUS group, the number of large follicles decreased from 1.3 on Day 12 to 0.5 on Day 15. Only 4 of 7 PGF cows ovulated a second-wave dominant follicle. In the BUS group, 7 of 8 cows ovulated a GnRH analogue induced dominant follicle that was first identified on Day 15. During the follicular phase (last 5 d prior to estrus), plasma progesterone declined in association with CL regression in both groups, and estradiol concentrations increased, reaching higher (P<.0.05) preovulatory peak concentration in BUS cows than in PGF cows (14.0 +/- 1.0 vs 10.4 +/- 1.1 pg/ml). The number of medium-size follicles was smaller and the number of small-size follicles tended to be higher in BUS cows than in the PGF-treated group. On the day of estrus, the size of the ovulatory follicle (16.1 vs 13.3 mm) and the size difference between the ovulatory and second largest follicle (11.4 vs 6.2 mm) were both larger in BUS cows than in PGF-treated cows, suggesting a more potent dominance effect of the ovulatory follicle in the BUS cows. This study suggests that a GnRH analogue can alter follicular development prior to synchronization of estrus with an injection of PGF(2alpha) in lactating dairy cows.

Journal Article↗
PubMed1986

[Follicular development in pregnancy and the polycystic ovarian syndrome].

In order to obtain some clues to the mechanism of follicular development, we studied sequential changes in circulatory hormone from spontaneous abortion up to the next ovulation in 11 women. In addition, morphological analysis of the follicles was performed in the ovarian tissue obtained from 4 pregnant women and another 4 women with polycystic ovarian syndrome (PCO). Blood was collected every 2-4 days and the serum samples were analyzed for HCG (LH), FSH, progesterone and estradiol by radioimmunoassay (RIA). Whole ovaries or the tissue obtained by ovarian wedge resection were sectioned serially at 2.5 micrometers. Every 13th slice was stained and examined under a light microscope. The present data were summarized as follows. A dominant follicle started to grow when LH.HCG levels declined to approximately 120 mIU l and FSH increased slightly. The largest nonatretic follicle seen in pregnancy or PCO was comparable with that seen in the late luteal phase of a normal cycle. The atretic rate of middle sized follicles (2.0 less than or equal to approximately less than 4.0 mm in diameter) was significantly higher in PCO than that seen in normal or pregnant women. These data indicate that the hormonal milieu of pregnancy or PCO does not interfere with the follicular development up to the stage of the largest nonatretic follicle seen in the late luteal phase of a normal cycle. This sized follicle grows to a dominant follicle within a short period under a minor stimulus by FSH.

Abortion, Spontaneous↗
PubMed1979

Effects of follicular development on the ability of cultured porcine granulosa cells to convert androgens to estrogens.

Porcine granulosa cells from different stages of follicular development were examined for their ability to convert androgens to estrogens and their ability to secrete progesterone. Granulosa cells from all stages of follicular development can convert androgens to estrogens, and the addition of exogenous androgen is required for estrogen secretion. Granulosa cells obtained from medium and large follicles have a greater capacity to convert androgens to estrogens than do granulosa cells obtained from small follicles. The addition of FSH brought about an increase in estrogen secretion in the presence of androgen only in granulosa cells from large follicles. LH attenuated estrogen secretion in granulosa cells from medium follicles treated with testosterone. Granulosa cells from medium follicles were unable to secrete estrogen from days two to four irrespective of treatment. Androgens augment FSH stimulated progesterone secretion in granulosa cells from medium follicles from days two to four, and the addition of follicular fluid from small follicles stimulates progesterone secretion in the presence of FSH and androgens.

Androgens↗
PubMed2005

Follicular development and maturation in gilts selected for an index of high ovulation rate and high prenatal survival.

Seventy-one 10th-generation gilts from White Line-1 (WL-1 = randomly selected control line) and White Line-2 (WL-2 = selected for an index of ovulation rate and prenatal survival rate) were used to compare the pattern of follicular development and atresia during the follicular phase of the estrous cycle. Gilts were treated with PGF(2alpha)on d 13 of the estrous cycle (d 0 of induced follicular development) to induce luteolysis and assigned randomly within line and sire for ovary recovery on d 0, 2, 3, 4, 5, and the day after estrus. Ovaries were evaluated for numbers of corpora albicantia and small (2 to 2.9 mm), medium (M1 = 3 to 4.9 mm; M2 = 5 to 6.9 mm), and large (>or=7 mm) follicles. The concentration of estradiol-17beta in follicular fluid was used to classify individual M2 and large follicles as estrogen-active (>or=100 ng of estradiol-17beta/mL) or inactive (<100 ng of estradiol-17beta/mL). The WL-2 gilts had a greater ovulation rate than WL-1 gilts at their pre-treatment estrus (20.4 vs. 13.8 corpora albicantia; P < 0.001). The small and M1 follicle populations decreased rapidly in both lines over time (P < 0.001). The M2 follicle population increased in both lines between d 0 to 4 and then decreased. Mean estradiol concentration of M2 follicles increased in both genetic lines over time (P < 0.02). All large follicles were estrogen-active in both lines; the number of large follicles increased with day (P < 0.001) and was similar in both lines. The number of estrogen-active M2 follicles was similar in both lines, increasing to d 3 and 4 and then decreasing (P < 0.01) thereafter. However, the total number of estrogen-active follicles (sum of estrogen-active M2 and large follicles) was greater in WL-2 than in WL-1 gilts (P < 0.04), increasing to the ovulatory potential by d 3 in WL-1 gilts, but continuing to increase through d 4 in WL-2 gilts. Selection of an additional six ovulatory follicles from the estrogen-active M2 follicle pool after d 5 was required in both lines to achieve the projected ovulation rate, and after estrus, the number of large follicles remained insufficient to attain the ovulatory potential of each line.

Animals↗