Ovules position

These three compounds differ from each other in the substitution pattern of the B-ring apimaysin has one hydroxyl group on the 4 position of the firing, maysin has a 3, 4 -dihydroxy substitution pattern, and methoxymaysin has a 4 -hydroxy, 3 -methoxy substitution pattern. These compounds accumulate in the silks of maize (i.e. the styles attached to the ovules) and are thought to act in a manner similar to chlorogenic acid (see Figure 6-1) when insects damage the silks. 

HCG is used medically to positively influence ovulation in women, and to help produce estrogen. It is also utilized in fertility medicine to aid in ovulation. 

Major constituent of normal vaginal flora, facultative or anaerobic gram-positive rods increased numbers during pregnancy, during ovulation, at menopause, and during steroid treatment... 

TCDD-exposed rats, suggesting that 2,3,7,8-TCDD inhibited the positive feedback action of 17 -estradiol at the hypothalamic-pituitary axis (Li et al. 1995a). In hypophysectomized rats, 2,3,7,8-TCDD exposure resulted in a reduction of ovulation Li et al. (1995a) suggests that this may be the result of a direct effect on the ovary, although the mechanism has not been elucidated. 

High levels of oestrogens then induce a positive feedback on the anterior pituitary in the late follicular phase to cause an increase in the level of LH. Following the LH surge, ovulation occurs and the ruptured follicle is converted to a corpus luteum. 

When self-regulating physiological systems (generally controlled by negative feedback systems, e.g. endocrine, cardiovascular) are subject to interference, their control mechanisms respond to minimise the effects of the interference and to restore the previous steady state or rhythm this is homeostasis. The previous state may be a normal function, e.g. ovulation (a rare example of a positive feedback mechanism), or an abnormal function, e.g. 

Albumin has been used to prevent the ovarian hyperstimulation syndrome (OHSS) associated with ovulation stimulation. In 98 women albumin had no positive effect on OHSS (3). Because of adverse effects, such as exacerbation of ascites in OHSS, nausea, vomiting, febrile reactions, allergic reactions, anaphylaxis, and the risk of... 

The ovules or megasori are transformed buds, destined to become seeds in the mature fruit. Their number varies from one to hundreds. In position, they are erect, growing upward from the base of the ovary, as in the Compositae ascending, turning upward from the side of the ovary or cell pendulous, like the last except that they turn downward horizontal, when directed straight outward suspended, hanging perpendicularly from the top of the ovary. 

The ovule consists of the following parts, the relative position of which is very important for identifying the type (see 70). A microscopical analysis is often necessary to make certain, but with soma practice the more common types can easily be recognized. 

The large bolus of LH released (preovulatory LH surge) in response to positive feedback by estradiol induces ovulation in about 1 day, probably by stimulation of production of granulosa plasminogen activator, which leads to formation of plasmin, an enzyme that may be responsible for the digestion of the basal lamina and, consequently, for the rupture of the follicle (ovulation). 

Several studies in women have reported that plasma nitrites and nitrates are highest during the follicular phase and peak at midcycle in both normally cycling women (Rosselli et al., 1994 Cicinelli et al., 1996) and in women undergoing hormonal stimulation of their cycles (Rosselli et al., 1994). In addition, follicular fluid nitrite and nitrate content correlated positively with IL-ip concentration and with the numbers of oocytes retrieved (Tao et al., 1997). Follicular fluid nitrite and nitrate content has also been reported to positively correlate with follicular volume in one study (Anteby et al., 1996) but to have no correlation with ovum diameter in another study (Sugino et al., 1996). While these data are correlative, these studies support a relationship between IL-ip-induced NO synthesis and ovulation. 

---