SPERM DISTRIBUTION IN FEMALE RABBITS: THE EFFECT OF OVARIAN STEROIDS

1974 ◽  
Vol 76 (4) ◽  
pp. 765-772 ◽  
Author(s):  
D. B. Morton ◽  
R. J. Fitzpatrick ◽  
T. D. Glover
Keyword(s):  
Cervix Uterus ◽  
Hormonal Treatment ◽  
The Other ◽  
Sperm Transport ◽  
Ovarian Steroids ◽  
Other Hand ◽  
Oestradiol Benzoate

ABSTRACT Oestradiol benzoate, progesterone and 20α-hydroxy-4-pregnen-3-one (20α-OH) were injected into ovariectomized rabbits and after either 4 or 5 days the rabbits were inseminated with a standardized inseminate, killed at 2 and 10 h after insemination and the number of spermatozoa in the vagina, cervix, uterus and oviducts was evaluated. The oestrogen increased the number of spermatozoa recovered from the cervix, uterus and oviduct compared with the control ovariectomized group receiving no hormonal treatment. The progestagens, on the other hand, tended to inhibit sperm transport through the cervix depending on the amount given. Injection of both oestrogen and progesterone simultaneously, illustrated their antagonistic actions. The effect of circulating progestagens on sperm transport during oestrus and pseudopregnancy is discussed, as well as their effects on the formation of the cervical reservoir.

Failure of sperm transport in relation to ewe infertility following prolonged grazing on oestrogenic pastures

1967 ◽  
Vol 18 (5) ◽  
pp. 755 ◽  
Author(s):  
RJ Lightfoot ◽  
KP Croker ◽  
HG Neil
Keyword(s):  
Fallopian Tube ◽  
Zona Pellucida ◽  
Cervix Uterus ◽  
The Other ◽  
Ovarian Activity ◽  
Fallopian Tubes ◽  
Motile Sperm ◽  
Sperm Transport ◽  
Causal Mechanisms ◽  
To Receive

Sixteen ewes were drawn from each of two ewe flocks, one of which had grazed on oestrogenic pastures for annual periods over the previous 5 years ("clover" treatment) while the other grazed on green oats ("oats" treatment). Fertility of ewes on the clover treatment had decreased progressively, whereas in those on the oats treatment it had remained high. Oestrous ewes were allocated alternately to receive either two or eight services then killed 24 hr post coitus and the numbers of sperm in the cervix, uterus, and fallopian tubes determined. There was no difference in ovarian activity between the two groups; however, highly significant differences were found in the numbers of sperm recovered from the cervix, uterus, and fallopian tubes. Average sperm numbers per fallopian tube were 17,160 and 350 for ewes on the oats and clover treatments respectively. In addition to the reduction in sperm numbers, both the percentage of motile sperm flushed from the cervix and the proportion of recovered ova with sperm attached to the zona pellucida were lower in ewes on the clover treatment. The results suggest that primary failure of sperm transport in ewes on the clover treatment occurred when sperm did not enter the cervix in adequate numbers following service. The significance of these observations in relation to possible causal mechanisms is discussed.

LUTEOLYTIC EFFECTS OF OESTRADIOL AFTER HYPOPHYSECTOMY OR PITUITARY STALK SECTION IN CYCLING SHEEP

1973 ◽  
Vol 73 (4) ◽  
pp. 635-642 ◽  
Author(s):  
R. Denamur ◽  
G. Kann
Keyword(s):  
Pituitary Gland ◽  
Life Span ◽  
Corpus Luteum ◽  
Direct Action ◽  
The Other ◽  
Pituitary Stalk ◽  
Relative Importance ◽  
Luteal Regression ◽  
Other Hand ◽  
Oestradiol Benzoate

ABSTRACT Experiments were carried out with a view to determining the relative importance of the pituitary gland and the uterus for the luteolytic action of oestradiol in the cycling ewe. The influence of the pituitary was modified by stalk section or hypophysectomy and that of the uterus by hysterectomy. Oestradiol (0.5 mg twice daily) caused an increase in ghe life-span of the corpus luteum (CL) if treatment began on day 3 of the cycle, and a decrease when injections commenced on days 9 or 11. Pituitary stalk sections performed on days 3 or 11 caused little change in CL weight on day 14. However, in either case, oestradiol administration from day 11 resulted in a large fall in CL weight, indicating that intact pituitary connections to the hypothalamus were not essential for the luteolytic action of oestradiol. Luteal regression following hypophysectomy on day 11 was accelerated by oestradiol benzoate injected from day 11. On the other hand, hysterectomy on day 11 always resulted in maintenance of the CL to day 20, whether or not stalk section or oestradiol administration had taken place. This indicated that the presence of the uterus was essential for the luteolytic effects of oestradiol. These experiments show that the luteolytic properties of oestradiol reflect mainly a direct action of this hormone on the uterus.

PRE-TRAUMA OESTROGEN REQUIREMENTS FOR INDUCTION OF DECIDUALIZATION IN SPAYED, PROGESTERONE-TREATED RATS

1966 ◽  
Vol 53 (2) ◽  
pp. 212-224 ◽  
Author(s):  
Carla Rossi Cartoni ◽  
G. Bignami
Keyword(s):  
Single Dose ◽  
Hormonal Treatment ◽  
Normal Pregnancy ◽  
Carbonic Anhydrase Activity ◽  
The Other ◽  
Ovariectomized Rats ◽  
Uterine Weight ◽  
Experimental Conditions ◽  
Progesterone Treatment ◽  
Oestradiol Benzoate

ABSTRACT The formation of deciduomata was investigated in ovariectomized rats treated with various combinations of oestrogen and progesterone before traumatization. The hormonal treatment was kept constant for all groups of animals during the period between traumatization and autopsy (4 mg of progesterone and 0.2 μg of oestradiol benzoate daily). Uterine weight and carbonic anhydrase activity were measured 96 hours after trauma and compared with those of intact controls receiving traumatization on day 4 of pseudopregnancy. When a single dose of oestrogen was given on the day before traumatization, induction of decidualization was successful under a wide variety of experimental conditions (presence or absence of oestrogen »priming« before the beginning of the progesterone treatment; progesterone treatment of varying duration). On the contrary, treatment with divided doses of oestrogen, given for 3 days before trauma, allowed extensive decidualization only in rats »primed« with oestrogen, and traumatized on the fourth day of a progesterone treatment started 24 hours after vaginal keratinization. It appears therefore that only the »oestrogen surge« hypothesis of Shelesnyak and his collaborators can account for those conditions in which implantation occurs at variable intervals of time after the last oestrus (lactation, hypophyseal autotransplantation, administration of a tranquilizer and early ovariectomy followed by hormonal treatment). On the other hand, both the hypothesis of Shelesnyak and that proposed by Yochim & DeFeo (1963) (i. e. continuous secretion of small amounts of oestrogen during the first three days of pregnancy and pseudopregnancy) could account for the rapid waxing and waning of endometrial sensitivity to deciduoma-inducing stimuli observed in normal pregnancy and pseudo-pregnancy.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

ON THE OTHER HAND

1961 ◽  
Vol 6 (6) ◽  
pp. 222-223
Author(s):  
Edwin G. Boring
Keyword(s):  
The Other ◽  
Other Hand
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