Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0277787 (stigma)
 13,352 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sequence of events within the ovary during the process of ovulation discussed in this review is schematically represented in Fig. 1. It is obvious that LH, perhaps with some contribution from FSH, is the normal physiological trigger for the ovulatory sequence of events, and it appears from the available information that the effects of LH are mainly mediated via adenylate cyclase and increased cAMP levels. The cAMP in turn, via cAMP-dependent protein kinase, influences at least three distinct steps in the ovulatory process which seem to be of crucial importance, namely 1) the stimulation of steroidogenesis; 2) the stimulation of cyclooxygenase/lipooxygenase leading to increased prostaglandin/leukotriene synthesis; and 3) the stimulation of plasminogen activator which catalyzes the conversion of plasminogen to plasmin. A fourth crucial step in the ovulatory mechanism is the LH-induced increase in latent collagenase, but it remains to be determined if this step is mediated via cAMP. Concomitant with the increase in latent collagenase, there also appears to be an LH-dependent increase in collagenase inhibitors. The latent collagenase is then activated, and it appears that leukotrienes and prostaglandins, as well as plasmin, may be involved in this process. The active collagenase causes a digestion of the collagen in the follicle wall, and plasmin, as well as possibly other proteolytic enzymes such as proteoglycanases, may cause a further dissociation of the follicular wall. These processes of digestion of collagen and dissociation of the collagen fibers result in an opening in the follicular wall with the formation of the stigma and rupture. While the weakening of the follicular wall takes place throughout the entire wall, rupture remains for the most part a localized process at the apex of the follicle. This localization of the rupture may be explained on the basis of mechanical factors operating when the follicle wall thins and weakens. While it is clear that prostaglandins and leukotrienes can influence smooth muscle by causing contractions and that these compounds can cause vascular changes such as increased permeability, vasodilation, and vasoconstriction, it is not clear what the exact role of these latter processes are in ovulation. It appears that progesterone and not estrogen play an important role in the mechanism of LH-induced follicular rupture, but the locus of action of progesterone and its mechanism of action remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mechanism of mammalian ovulation. 255 97

The sequence of ovarian events during the process of ovulation discussed in this review is schematically represented in Figure 1. It is obvious that LH, perhaps with some contribution from FSH, is the normal physiological trigger for the ovulatory sequence of events and it appears from the available information that LH's effects are mainly mediated via adenylate cyclase and increased cAMP. The cAMP in turn, via cAMP-dependent protein kinase, influences at least three distinct steps in the ovulatory process which seem to be of crucial importance, namely 1) the stimulation of steroidogenesis; 2) the stimulation of cyclooxygenase/lipooxygenase leading to increased prostaglandin/leukotriene synthesis; and 3) the stimulation of plasminogen activator which catalyzes the conversion of plasminogen to plasmin. A fourth crucial step in the ovulatory mechanism is the LH-induced increase in latent collagenase, but it remains to be determined if this step is mediated via cAMP. Concomitant with the increase in latent collagenase, there also appears to be an LH-dependent increase in collagenase inhibitors. The latent collagenase is then activated and it appears that leukotrienes and prostaglandins as well as plasmin may be involved in this process. The active collagenase causes a digestion of the collagen in the follicle wall. Plasmin as well as possibly other proteolytic enzymes such as proteoglycanases (Too et al., 1984) may cause a further dissociation of the follicular wall. These processes of digestion of collagen and dissociation of the collagen fibers result in an opening in the follicular wall with the formation of the stigma and rupture. While the weakening of the follicular wall takes place throughout the entire wall, rupture remains for the most part a localized process at the apex of the follicle. This localization of the rupture may be explained on the basis of mechanical factors operating when the follicle wall thins and weakens (Rodbard, 1984). While it is clear that prostaglandins and leukotrienes can influence smooth muscle by causing contractions and that these compounds can cause vascular changes such as increased permeability, vasodilatation and vasoconstriction, it is not clear what the exact role of these latter processes are in ovulation. It appears that progesterone and not estrogen play an important role in the mechanism of LH induced follicular rupture, but the locus of action of progesterone and its mechanism of action remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mechanism of mammalian ovulation. 265 83

FSH, LH, estradiol and progesterone were serially assayed during 8 cycles of six subjects using six subdermal implants releasing levonorgestrel (NORPLANT) for a period of 2 to 6 years. All 8 cycles studied had a very low LH peak and a low or nonexistent FSH peak as compared to 8 control cycles. The mean LH peak for NORPLANT users was 33.9 mIU/ml as compared to 142 mIU/ml in the control group; and FSH was 13.0 mIU/ml as compared to 31.3 mIU/ml in controls. A subsequent rise in progesterone was observed in the 8 cycles studied, but the mean mid-luteal levels were significantly lower than in controls (9.0 ng/ml vs. 15.6 ng/ml). No differences were observed in the estradiol curve. Two of the subjects using NORPLANT had a laparotomy performed on days 17 and 20 of the cycle, for surgical sterilization purposes. A distinctive corpus luteum with a stigma was observed. Our results indicate that women under prolonged use of NORPLANT do not have normal endocrine cycles, even though they may ovulate. It is doubtful however, that these ovulatory cycles can be fertile under the abnormal endocrine conditions found in our subjects. In addition to the possible effect of luteal insufficiency, the normal maturation of the oocyte may be impaired.
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PMID:Abnormal endocrine profile among women with confirmed or presumed ovulation during long-term Norplant use. 308 66

Although much is known about morphological changes in the apex of the mammalian ovarian follicle prior to its rupture (ovulation), information about this process in nonmammalian vertebrates is limited to only a few species. We describe here the histological changes in the stigma of the lizard (Anolis carolinensis) ovarian follicle preceding FSH-induced ovulation. Females with a large vitellogenic follicle received two injections, separated by 7 hr, of either porcine FSH (25 micrograms) or saline, and then were sampled at 6, 9, 12, 15, 18, and 24 hr after the first injection. Thus, all but the 6-hr group received two injections. By 12 hr, about half of the FSH-treated females had ovulated, and most had ovulated by 15 hr. In contrast, only 1 of 40 control females ovulated. Large unovulated follicles were fixed and bisected through the circular stigma; one hemisphere was embedded in paraffin and stained with Mallory's trichrome, and the other was embedded in plastic and stained with toluidine blue. FSH treatment produced marked histological changes in the stigma region, as well as alterations in nonstigmal areas of the follicle. The membrana granulosa of control follicles consisted of a single layer of squamous, darkly staining granulosa cells. After FSH treatment, nonstigmal granulosa cells separated slightly, and their nuclei became more clear and assumed an oval shape; in the stigma, these cells became widely separated, with round, light-staining nuclei containing one or two prominent nucleoli. The nonstigmal theca of FSH-treated follicles was similar to that of control follicles except that collagen fibers were more dissociated. In the stigma, collagen fibers were widely dissociated, and the theca swelled, presumably due to accumulation of extracellular fluid. Abundant fluid accumulated in the stigma, especially between the granulosa cells and their basement membrane and between the tunica albuginea and the theca externa. These changes in the lizard stigma are similar to those reported in mammals except that no marked inflammatory response occurs in the lizard stigma. We hypothesize that the Anolis follicle undergoes preovulatory luteinization, and that the stigma exhibits ischemic necrosis before rupture.
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PMID:Gonadotropin-induced ovulation in a reptile (Anolis carolinensis): histological observations. 314 17

Fourteen cases of endometriosis (Em) with infertility were studied by laparoscopy in our hospital from Dec. 1988 to Oct. 1989. 2 cases were minimal, 6 cases were moderate and 6 cases were severe. The salpingo examinations of 13 cases were normal by laparoscopy. There were no stigma on ovaries in 7 cases (LUFS). Levels of hormone (E2,P,LH,FSH) were compared in Em with normal women. The level of E2 during the follicle phase in Em was lower (86.4 +/- 6.9 pg/ml) than in normal women (119.9 +/- 7.7 pg/ml, P < 0.01). The LUFS group was compared with the no-LUFS group in Em. During the mid-late follicle phase and ovulatory phase, the E2 values in the LUFS group was significantly lower than in the non-LUFS group (P < 0.05), while the FSH value in LUFS group was significantly higher than in non-LUFS group (P < 0.05).
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PMID:[Cyclic changes of serum reproductive hormone levels on patients with endometriosis and infertility]. 772 Jan 49