Alfvénic velocity spikes and rotational flows in the near-Sun solar wind.

The prediction of a supersonic solar wind1 was first confirmed by spacecraft near Earth2,3 and later by spacecraft at heliocentric distances as small as 62 solar radii4. These missions showed that plasma accelerates as it emerges from the corona, aided by unidentified processes that transport energy outwards from the Sun before depositing it in the wind. Alfvénic fluctuations are a promising candidate for such a process because they are seen in the corona and solar wind and contain considerable energy5-7. Magnetic tension forces the corona to co-rotate with the Sun, but any residual rotation far from the Sun reported until now has been much smaller than the amplitude of waves and deflections from interacting wind streams8. Here we report observations of solar-wind plasma at heliocentric distances of about 35 solar radii9-11, well within the distance at which stream interactions become important. We find that Alfvén waves organize into structured velocity spikes with duration of up to minutes, which are associated with propagating S-like bends in the magnetic-field lines. We detect an increasing rotational component to the flow velocity of the solar wind around the Sun, peaking at 35 to 50 kilometres per second-considerably above the amplitude of the waves. These flows exceed classical velocity predictions of a few kilometres per second, challenging models of circulation in the corona and calling into question our understanding of how stars lose angular momentum and spin down as they age12-14.

Fertilizability of ova ovulated and recovered from rabbit ovaries perfused in vitro.

Ovaries removed from New Zealand White rabbits were perfused and exposed to gonadotropin in vitro. The ova ovulated in vitro (N = 56) were recovered and cultured and then transferred to the oviducts of six previously mated Dutch Belted hosts. Twelve of the resulting 36 offspring (33.3 percent) were white. In control matings between 12 Dutch Belted females (six randomly selected and the six hosts) and New Zealand White males, only one of 80 (1.2 percent) offspring was white. These data indicate that ova ovulated in vitro can be transferred to the oviduct of a host rabbit where they may be fertilized and after implantation may develop into viable embryos.

The effects of cholinergic agents on ovarian contractility in the rabbit.

Cholinergic nerves have been recognized in the ovaries of several species. Smooth muscle fibers have also been demonstrated within the ovary, and it has been suggested that these elements are involved in the ovulatory process. Ovarian contractility was investigated in 49 ovaries from 25 rabbits in in vivo and in vitro systems and correlated with the time of hCG-induced ovulation. Effects of 6 cholinergic drugs on ovarian contractility were recorded at various intervals from 6 to 20 hours after administration of hCG. Cholinergic agents were administered via the abdominal aorta in the in vivo preparations and added to the bath for in vitro studies. In general, acetylcholine, bethanechol and pilocarpine exerted variable effects. Atropine depressed ovarian contractile activity. No definitive pattern of altered sensitivity to cholinergic drugs could be identified as the time of ovulation was approached; however, a relationship was observed between the amount of cholinergic drug administered and effects on ovarian contractions.

Selective ovarian sympathectomy in the rabbit.

Evidence implicates the ovarian nerves in the regulation of hormonal and ovulatory functions. A technique for selectively denervating the in situ rabbit ovary is therefore of considerable investigative value. The ovarian artery was stripped of its adventitia and nerve bundles. Three weeks later, fluorescent histochemistry confirmed the complete absence of adrenergic nerves in the vessel walls and ovarian stroma of the experimental ovary, as compared to the abundant fluorescent structures present in the contralateral control ovary. The surgically treated ovaries demonstrated no significant ischemic or trophic change on gross and routine histologic examination.

Studies on the function of the denervated rabbit ovary: human chorionic gonadotropin-induced ovulation.

The described method for selective sympathetic denervation of the in vivo rabbit ovary involved stripping the ovarian artery of its nerve bundles and adventitial tissue. The ovary was then entirely free of fluorescent-staining adrenergic nerves. This technique was used to study the effects of ovarian denervation on HCG-induced ovulation. After HCG was administered to 22 rabbits which had previously undergone unilateral ovarian denervation, the ovaries were observed for follicular maturation and rupture. Control ovaries demonstrated a mean of 5.6 stimulated follicles/ovary; denervated ovaries had a mean of 5.4. An average of 3.5 follicles/control ovary ruptured; an average of 3.1 follicles/denervated ovary ruptured. Furthermore, the time course of ovulation after HCG did not differ between denervated and intact ovaries. These results indicate that HCG-induced ovulation in the rabbit is not interrupted by ovarian denervation.

Lack of effect of ovarian denervation on ovulation and pregnancy in the rabbit.

Following unilateral ovarian denervation by ovarian artery stripping in female rabbits, ovulation and pregnancy were achieved within 3 days of denervation. Three weeks later, at repeat laparotomy, ovarian dimensions and the numbers of corpora lutea and pregnancies were noted. Fluorescent histochemical studies confirmed complete adrenergic denervation in five of the rabbits' ovaries. There was no significant difference in ovarian dimensions, numbers of corpora lutea and pregnancies, or the excess of corpora lutea over implantations when the intact control side was compared with the denervated side. The control ovaries demonstrated an average of 5 corpora lutea/ovary and an average of 3.4 conceptuses in the adjacent uterine horn, while the numbers on the denervated side were 5 and 3.2, respectively. Although these findings demonstrate that central neural efferent control is not essential for the occurrence of pregnancy after mating in the rabbit, the potential significance of ovarian neuromuscular mechanisms in these functions is discussed, and future studies are suggested.

In vitro reversal of indomethacin-blocked ovulation by prostaglandin F2alpha.

An in vitro perfused ovary preparation was used to study the role of prostaglandin F2alpha (PGF2alpha) in follicle rupture. The administration of PGF2alpha alone has been shown to restore indomethacin-blocked ovulation in rabbits and monkeys. In the model used, ovulation consistently occurred when human chorionic gonadotropin (hCG) was given to the intact rabbit prior to ovarian removal. hCG-induced ovulation was blocked in both perfused and in situ control ovaries by indomethacin (10 mg/kg intravenously 6 hours after hCG) given to the intact animal. The addition of PGF2alpha (1 mg/200 ml) to the perfusion fluid restored ovulation in the isolated ovary as compared with the in situ ovary (P less than 0.005) and with the perfused, untreated ovary (P less than 0.01). Following removal and perfusion of both ovaries from rabbits treated with indomethacin, ovulation occurred following the addition of PGF2alpha to the perfusate, but did not occur without PGF2alpha (P less than 0.05). These data indicate that indomethacin can block ovulation and that ovulation can be restored by the addition of PGF2alpha to the perfusion system, further supporting the significance of PGF2alpha in the process of follicular rupture.

Studies of rabbit ovarian contractility using chronically implanted transducers.

A chronically implanted, highly sensitive force transducer was used to study ovarian contractions in the rabbit. The transducer is implanted into the medulla of the ovary through its long axis. The leads are then drawn through the abdominal wall and directed subcutaneously to the back of the neck. The miniature pin connector is fixed into place beneath the skin to facilitate accessibility for repeated recordings, obviating the necessity for anesthesia or serial laparotomies. Intraovarian transducers were implanted in isolated rabbits. Serial recordings of ovarian contractions were made at weekly intervals for 3 weeks, following which ovulation was induced with 100 IU of human chorionic gonadotropin (HCG). Extended recordings were made from 3 through 13 hours after HCG administration to six animals. Recordings revealed increased ovarian contractile activity beginning just before the anticipated time of ovulation. The observations support those of previous acute experiments and demonstrate a relationship between ovarian contractile activity and the process of follicle rupture.

Influence of estrogen and progesterone treatment on ovarian contractility in the monkey.

Five female rhesus monkeys were treated with natural estrogens, 5 mg/day for three weeks, after which ovarian contractility was studied in vitro in one of the ovaries. Estrogen treatment was followed by progesterone, 25 mg/day for three weeks, after which the contractility of the remaining ovary was similarly measured. Responses to autonomic agents and prostaglandins were studied in both groups. Spontaneous ovarian contractility and ovarian contractile responsiveness to prostaglandins and norepinephrine were found to be enhanced after progesterone treatment. Cholinergic agonists had a stimulatory effect after progesterone and an inhibitory effect after estrogens. Our results suggest that ovarian contractile responsiveness is modified by the local steroid environment, perhaps through intracellular changes in cyclic AMP.

Ultrastructure of ovarian follicles in in vitro perfused rabbit ovaries: response to human chorionic gonadotropin and comparison with in vivo observations.

Ovulation may be achieved and studied in an isolated perfused rabbit ovary upon inclusion of human chorionic gonadotropin (hCG) in the perfusion fluid. The ultrastructural features of the rabbit ovarian follicle prior to ovulation in vitro were compared with those in vivo. The perifollicular vasculature was also examined in in vitro perfused rabbit ovaries during the preovulatory interval. Granulosa cells of the preovulatory follicle share many ultrastructural features in vivo and in vitro; however, only small amounts of smooth endoplasmic reticulum (sER) were observed in granulosa cells in vitro after hCG. Ovulation after hCG in the in vitro preparation tends to occur earlier (6 hours) than in vivo (12 hours). Thus, there may be insufficient time and/or gonadotropin exposure to permit full functional development of granulosa cells, as reflected by reduced amounts of sER. Degradation of collagen fibrils was less prominent in the theca externa and tunica albuginea in vitro than in in vivo. Perifollicular capillaries became dilated after hCG, but interendothelial gaps were not observed. Disappearance of surface epithelium in the apex of follicles was similar in vitro and in vivo.

In vitro studies of ovulation in the perfused rabbit ovary.

A system has been developed for the perfusion of the rabbit ovary in vitro. At laparotomy, the ovarian artery is cannulated and perfused with M 199 tissue culture medium containing insulin and heparin, then removed with its vascular pedicle intact. Perfusion at 37 degrees C is maintained by using a capillary oxygenator and Buchler roller pump. The functional integrity of the perfused ovary is confirmed by serial determinations of the perfusate pH, glucose and lactate concentrations, and by ovarian histology. This in vitro model was used to study the mechanism of ovulation. One group of isolated rabbits received human chorionic gonadotropin (50 IU, intravenously) and, 8 hours later, one ovary was removed and perfused; the contralateral ovary remained in situ, serving as an in vivo control. Serial observations for follicle development and rupture were made over the subsequent 7-hour interval. The occurrence of ovulation in vitro was documented by time-lapse photography. In each animal, comparisons made between the in vitro and in vivo ovary indicated that the rate and time of follicle maturation and ovulation were comparable. Ovulation occurred between 10 and 15 hours after administration of human chorionic gonadotropin in both preparations.

The relationship between prostaglandins and histamine in the ovulatory process as determined with the in vitro perfused rabbit ovary.

The process of follicle rupture has been described as an inflammatory reaction in which prostaglandins (PGs) and/or histamine may be involved. With an in vitro perfused rabbit ovary preparation, experiments were carried out for determination of whether a relationship exists among PGs, histamine, and ovulation. PGF2 alpha alone was capable of inducing ovulation when added to the perfusion fluid at 1, 10, and 100 ng/ ml. Effectiveness in achieving ovulation varied directly with the dosage; however, the ovulatory efficiency of PGF2 alpha-treated ovaries was lower than that of ovaries exposed to human chorionic gonadotropin (hCG, 100 IU). PGF2 alpha-induced ovulation could not be blocked by the H2 receptor antagonist, cimetidine. The PG synthesis inhibitor, indomethacin, did not prevent histamine-induced ovulation. Ovulation induced by hCG was partially blocked by the administration of indomethacin; however, the concomitant administration of cimetidine was not associated with further reduction in ovulation. In all but one experimental group, the majority of ovulated ova did not progress beyond the intact germinal vesicle stage unless the ovaries had been exposed to hCG. On the basis of these experiments, PGs and histamine do not appear to be interdependent in their effects on the ovulatory process in vitro.

The effect of dexamethasone and promethazine administration on adhesion formation, tubal function, and ultrastructure following microsurgical anastomosis of rabbit oviducts.

In a controlled study, 24 rabbits underwent bilateral division and immediate microsurgical anastomosis of the oviducts. Dexamethasone and promethazine were administered to 13 rabbits in a dose and route of administration similar to those used in clinical practice. Eleven control rabbits received a saline vehicle. Morbidity and mortality were encountered only in the dexamethasone and promethazine-treated group. Dexamethasone and promethazine did not appear to influence the formation of intraluminal and peritubal adhesions, histology, ultrastructure, patency, implantation, or pregnancy rates. The presence of intraluminal adhesions, as seen by scanning electron microscopy, was associated with relatively more efficient tubal function as measured by the ability of the oviducts to convey ova to intrauterine implantation sites. Collagen accumulation in the muscularis, as demonstrated by trichrome staining, was associated with relatively decreased tubal function.

Cooling rate effect on outgrowth of Clostridium perfringens in cooked, ready-to-eat turkey breast roasts.

The potential for Clostridium perfringens spores to germinate and grow in cooked, ready-to-eat turkey products was evaluated to determine a safe cooling rate within the critical temperatures of 48.9 C (120 F) through 12.8 C (55 F). Raw turkey deli breast roasts were inoculated with a cocktail of C. perfringens spores (NCTC 8238, NCTC 8239, and NCTC 10388) and cooked in a steam oven to an internal temperature of 72 C. The sample roasts were then cooled through the critical cooling range at rates yielding cooling times of 6, 8, and 10 h. Turkey roasts were analyzed for spore growth and multiplication using tryptose-sulfite-cycloserine agar and anaerobic incubation at 37 C for 48 h. Cooling times of 6 and 8 h showed no proliferation of C. perfringens that would violate the USDA/Food Safety Inspection Service safe cooling standard criteria, which would allow no more than a 1 log10 multiplication between 48.9 and 12.8 C. A 9.6-h cooling period between the designated temperatures at a 95% confidence interval was determined to be adequate for nonproliferation of C. perfringens. On the other hand, a 95% tolerance interval would be more stringent in that it suggests no more than an 8.9-h cooling period. Tolerance intervals required that 95% of all our observations did not exceed the limit of 1 log10 increase in C. perfringens. This study indicated that in cooked, ready-to-eat turkey deli breasts, a cooling period between 48.9 C (120 F) and 12.8 C (55 F) of no greater than 8.9 h should be utilized to prevent possible C. perfringens foodborne outbreaks.