Some observations on the physiology of reproduction in the greyhound bitch.
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Animals↗
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Results for “Reproductive Period”
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Effect of exposure to long photoperiod during the rearing period on the age at first egg and the subsequent reproductive performance in geese.
The objective of this study was to investigate the effects of photoperiods longer than 14 h of light:10 h of dark (14L:10D) during the rearing period on the age at first egg laying (AFE) and the subsequent reproductive performance in geese. Sixty-six White Roman geese (18 male and 48 female) were divided into three groups and subjected to different lighting schemes, i.e. natural lighting (NAT; 23 degrees 51'N, 120 degrees 33'E), 14L and 18L. Birds in 14L and 18L groups were exposed to 14L:10D or 18L:6D, respectively, beginning at 19 weeks of age and followed by a photoperiod of 10L:14D from 40 weeks of age. The natural photoperiod, including both dawn and dusk was between 11.5L:12.5D and 14.5L:9.5D. The results showed that the AFE was postponed (P < 0.05). Average weight of the first three eggs laid and the fertility of these eggs were improved (P < 0.05) for the geese in 14L and 18L groups when compared to those raised under natural lighting conditions. Meanwhile, the duration of laying were shifted from spring to autumn, with the peak laying rate in September and November instead of March. It was concluded that geese exposed to the photoperiod longer than 14L:10D for 21 weeks during the rearing period would suppress their AFE. Thereafter, the onset of laying could be induced by being transferred to the photoperiod of 10L:14D. The manipulation of photoperiodic regimes used in this study might have a potential benefit for geese farmers through improved weight and fertility of eggs.
Aging↗
Influence of photoperiod on the pregnant and postpartum mare.
Over a 2-year period, mares (n = 32) of predominantly Quarter Horse breeding and their foals were used to study the effects of photoperiod on reproduction during the periparturient period. Specific objectives of the study were (i) to evaluate the effects of an extended photoperiod regimen (16 hours' light) on gestation length, foal development, and postpartum reproductive performance, and (ii) to measure changes in plasma progesterone concentrations during the last trimester of gestation and plasma luteinizing hormone (LH) concentrations after foaling until ovulation. Mares in the extended daylength treatment group had shorter (10 days) mean gestation length (P less than 0.01) than did control mares (exposed to normal daylight hours). Although foals of mares exposed to long photoperiod were carried for a shorter term, their birth weights tended to be heavier, but not significantly, than those of foals from control mares. Foal size, as determined by body measurements, was not affected by the photoperiod. Neither interval from parturition to 1st ovulation nor onset of estrus to ovulation were significantly affected by the extended photoperiod. Plasma progestogen concentrations increased from basal levels at prepartum weeks 4 and 5 to peak values a week before foaling in both mare groups. The LH profiles from parturition to ovulation were similar for both mare groups. However, mean plasma LH values during the 7 days before the 1st ovulation were higher (P less than 0.05) in mares exposed to extended daylength than in control mares.
Animals↗
Phenology and pollination biology of eight Peperomia species (Piperaceae) in semideciduous forests in southeastern Brazil.
Data on flowering phenology and pollination of Peperomia species are virtually non-existent. This study presents data on the pollination biology of eight Peperomia species from south-eastern Brazil, including the flowering phenology, pollination system, and reproductive success. Data on flowering phenology were recorded weekly and exclusion experiments on inflorescences provided data on autonomous self- and wind pollination. Direct visual observations were made and insect visits were recorded. Four Peperomia species showed continuous flowering, while the others were seasonal and flowered in the wet season. Pollination by wind and Syrphidae was confirmed for two self-incompatible Peperomia species. The remaining species are self-compatible and their high fruit set may be accounted for by autonomous self-pollination and perhaps agamospermy. Although the floral morphology of Peperomia species suggests wind- and/or insect pollination, most of the species studied exhibit autogamy and perhaps agamospermy as the main method of reproduction.
Brazil↗
Investigation by meta-analysis of the effect of prostaglandin F2 alpha administered post partum on the reproductive performance of dairy cattle.
The effects of injecting prostaglandin F2 alpha (PGF) in dairy cattle within 40 days of calving on the rate of pregnancy at first service and on the number of days open were investigated by meta-analysis, by pooling data from numerous independent trials into single analyses. A total of 4052 cows from 24 trials described in 10 papers were included in the analyses of first service pregnancy rate and 2646 cows from 21 trials described in nine papers in the analyses of the number of days open. The analyses were stratified by trial and by the reproductive health of the cows after calving. Treatment with PGF during this early post partum period had no significant effect on the first service pregnancy rate of cows with a normal or abnormal puerperium. An analysis of the data for the number of days open by effect-size methods showed that a significant percentage (54 per cent) of the treated cows had fewer days open than the untreated cows, and that this difference tended to be greater for cows with an abnormal puerperium (59 per cent of treated cows). The weighted average reduction in days open between the treated and control cows was 2.6 days for trials with abnormal cows, and 3.3 days for trials including normal and abnormal cows. However, the calculation of the fail-safe number (F) indicated that it would require only a few studies with a negative response to PGF to negate this finding. Meta-analysis was a useful technique for evaluating the apparently conflicting results of previous studies.
Animals↗
Relation between phase of menstrual cycle and emergency department visits for acute asthma.
Hormonal fluctuations during the menstrual cycle are hypothesized to influence the course of asthma among women. A recent study found that almost 50% of emergency department (ED) visits occur during the perimenstrual phase. Our prospective cohort study in 64 EDs examined the relation between phase of menstrual cycle and visits for acute asthma. A total of 288 women with acute asthma were evaluated with a standardized patient interview and medical record review after excluding subjects who were pregnant, on hormonal therapy, postmenopausal, status post hysterectomy, had incomplete reproductive data, or whose ED visit fell more than 28 d after their last menstrual period. Only 13% reported reproductive factors as a personal asthma trigger. For all subjects, ED asthma visits were classified by menstrual phase: 33% were preovulatory (Days 5 to 11), 26% were periovulatory (Days 12 to 18), 20% were postovulatory (Days 19 to 25), and 21% were perimenstrual (Days 26 to 4), p = 0.008. There was no significant association between phase of menstrual cycle and asthma severity. Our data indicate that ED visits for acute asthma among women are more frequent during the preovulatory phase in contrast to other studies reporting more visits in the perimenstrual phase.
Acute Disease↗
[Quantitative description of the resistance of microbiological indicators by means of characteristic data (author's transl)].
The ambiguity of the quantitative description of the resistance of microbiological indicators by means of the terms common thus far, namely "resistance" (maximal period of action after which all indicators still exhibit organisms capable of reproduction) and "death time" (minimal period of action after which organisms capable of reproduction cannot be demonstrated any more in any of the indicators) is shown. Among other factors, the probability that all indicators will yield identical findings (sterility or growth of surviving organisms) at a defined time, is dependent upon the number of indicators in each case. The more indicators are tested, the lower "resistance" and the later the "death time" will be. Instead of times when all indicators present an identical reaction, times (or values related to these times in a defined way) should be taken at which indicators show the absence of organisms or the presence of surviving ones with a defined frequency. There is a defined relationship between the frequency of indicators found free from (resp. containing) surviving organisms and the number of surviving organisms per indicator (cf. Figs. 1 and 2). If the regularity of the decrease of organisms with the period of action of the destroying agent is known, 2 values are sufficient for a clear description of the resistance of a preparation of microbiological indicators. As characteristic values those values of action are proposed after which 99% and 1% of indicators will exhibit surviving organisms (t99% and t1%, respectively). The period during which the dependence of the frequency of presence of sterile indicators (po) upon the period of action of the destroying agent may be determined with sufficient precision and at justifiable experimental expenditure, is corresponding to a decrease of surviving organisms to appr. 1/30. From practical experience, it will be justified in the preponderant majority of cases to assume a logarithmic orderof death as given. Under such conditions, there will be a clear relationship between lg(-ln po) and the period of action of the destroying agent, so that test results may be easily evaluated by means of a simple graphical method or regression calculation. Graphical (FIG. 3) and mathematical determination of characteristic values from the frequency of indicators exhibitoring surviving organisms in the destruction test, after different periods of action, is explained by means of an example (Fig. 3; Tables 2 and 3) and a calculation (Table 1). To keep variation of experimental results sufficiently low, at least 30 (if possible 50) indicators per period of action should be studied for surviving organisms (cf. Fig 4). When evaluating results, different weights of the individual values and their asymmetric distribution around a maximum at t80% (Fig 5) should be taken into consideration.
Bacteriological Techniques↗
Progressive changes in LH and FSH and LH: FSH ratio in women throughout reproductive life.
Gonadotropin secretion during the post-menopausal period is considerably higher than during the reproductive years. In this study, we present evidence that changes in the hypothalamic-pituitary-ovarian unit occur over a period of years before the onset of menstrual irregularity which heralds the menopause. FSH and LH were measured in blood samples taken on 6 days during the mid-follicular phase from 127 regularly cycling women aged between 23 and 49 yr. The women aged 23-30 yr were taken as the control group and the remainder were grouped in 2-yr age bands. A significant increase in FSH underwent a further increase in the oldest group (48-49 yr) in whom LH also became significantly elevated. The difference in the timing of the change in FSH and LH concentrations was related not only to chronological age but also to the number of years before the menopause. The increase in FSH occurred 5-6 yr pre-menopause, that in LH not until 3-4 yr before the cessation of menstruation. It is concluded that an early sign of the aging of the reproductive mechanism can be detected in women who are having normal ovulatory cycles. The regulation of FSH and LH secretion appears to be sufficiently independent to permit the observed differences in the age of onset of these premenopausal increases.
Adult↗
[Tempo and parity structure of Japanese fertility].
The present study is part of a larger project on the formal demographic analysis of Japanese fertility. It deals with the most elusive aspect of fertility, that is the tempo of fertility. The temporal aspect of fertility, particularly in terms of cohort fertility framework with speical reference to parity of women, has been emphasized by Whelpton and Ryder, but in the Japanese demography there have scarcely been studies of this aspect, probably due to lack of interest. In very recent years, however, interest has grown, reflecting the need for more accurate fertility projections in the future in connection with population projections. The present study is an application of life table techniques to explore the temporal aspect of fertility in Japan. 2 methods have been used. One is the age-marriage-parity specific net reproduction rate tables, which were first constructed by the senior author of this paper. The other is by Professor Chin Long Chiang at the University of California, Berkely. In the application of the former type, net reproduction rate tables were constructed for 3 dates -- 1970-71, 1975-76, and 1980-81. Through this method, it was demonstrated that recent fertility for the period 1980-81 was reduced, partly because of the decline in fertility in live-birth order of 1 and 2 among the relatively young ages up to 25 years old. On the other hand, for the ages up to 30 years old, some catching-up mechanisms took place. The 2nd method is by Chiang's new approach to the fertility table. According to his method, which was included in his new book entitled Life Tables and Its Applications, parity-oriented fertility tables have been constructed for the Japanese females for every year from 1971 through 1983, both inclusive. In these cases, denominator is for year z while numerator is concerned with yea z + 1. This method is particularly interesting since it can calculate waiting time for childbearing until the completion of family formation. Some of the findings indicated: 1) recent increases in both parity progession ratio and parity-specific fertility rate in low parity augur a future increase in fertility in the period measure in the near future; and 2) a shortening of the waiting time until the completion of family formation around 1981 and then the recovery of its lengthening in the years 1982 and 1983 suggest a recent trend of lengthening actual reproductive period which definitely contributes to an increase in fertility.
Asia↗
The effects of assisted reproduction on the trends and zygosity of multiple births in England and Wales 1974-99.
Assisted reproductive techniques have led to an increase in the proportion of maternities that are multiple. Though predominantly dizygotic, they are at greater risk of monozygotic division than those spontaneously conceived. England and Wales data 1974-99 on stillbirths and livebirths were analysed for 4 periods: 1974-80 (pre-assisted reproduction; 1982-8; 1989-91 (pre-redefinition of stillbirth); 1993-9 (post-redefinition of stillbirth). For twin data, Weinberg's rule was applied to estimate the proportions that were mono- (MZ) and dizygotic (DZ). Compared with the period before assisted reproduction, the most recent period shows an increase in twin maternities of 3.81 per 1,000 comprised of 3.22 (95% CI 3.10 to 3.33; p < 0.0001) DZ and 0.60 (95% CI 0.51 to 0.68; p < 0.0001) MZ twins. It is estimated that 15.7% of assisted reproduction twins are MZ. Higher order multiple births showed an increase of 3.06 (95% CI 2.85 to 3.29; p < 0.0001) per 10,000 maternities. Stillbirth rates in MZ twins are of the same order of magnitude as those in higher order multiple births but higher than those in DZ twins. The improvement in stillbirth rates over the 26 year study period is of the same order magnitude in singletons, DZ and MZ twins and higher order multiples. Assisted reproduction has led to a significant increase in the proportion of MZ twins. These are at high risk of fetal death and this needs to be considered when local stillbirth and perinatal mortality rates are used in auditing obstetric services.
England↗
The influence of seasonal atmospheric factors on human reproduction.
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Birth Rate↗
Isolation, characterization and molecular cloning of cathepsin D from lizard ovary: changes in enzyme activity and mRNA expression throughout ovarian cycle.
During vitellogenesis, the oocytes of oviparous species accumulate in the cytoplasm a large amount of proteic nutrients synthetized in the liver. Once incorporated into the oocytes, these nutrients, especially represented by vitellogenin (VTG) and very low-density lipoprotein (VLDL), are cleaved into a characteristic set of polypeptides forming yolk platelets. We have studied the molecular mechanisms involved in yolk formation in a reptilian species Podarcis sicula, a lizard characterized by a seasonal reproductive cycle. Our results demonstrate the existence in the lizard ovary of an aspartic proteinase having a maximal activity at acidic pH and a molecular mass of 40 kDa. The full-length aspartic proteinase cDNA produced from total RNA by RT-PCR is 1,442 base pairs long and encodes a protein of 403 amino acids. A comparison of the proteic sequence with aspartic proteinases from various sources demonstrates that the lizard enzyme is a cathepsin D. Lizard ovarian cathepsin D activity is maximal in June, in coincidence with vitellogenesis and ovulation, and is especially abundant in vitellogenic follicles and in eggs. Ovarian cathepsin D activity can be enhanced during the resting period by treatment with FSH in vivo. Northern blot analysis shows that cathepsin D mRNA is exceedingly abundant during the reproductive period, and accumulates preferentially in previtellogenic oocytes.
Amino Acid Sequence↗
Relationship between adenylate cyclase sensitivity to follitropin and FSH receptor mRNA expression in the ovary of the lizard Podarcis sicula.
In mammals, gonadal functions are regulated by two pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), that interact with gonadal membrane receptors to activate adenylate cyclase. In comparison to mammalian systems, in squamate reptiles a reduced amount of information exists on gonadotropins and their related receptors. This study is aimed at clarifying if, in the lizard Podarcis sicula, the ovarian sensitivity to FSH is correlated to the reproductive cycle and to the expression of membrane receptors involved in the hormone recognition. The results demonstrate that the ovarian adenylate cyclase responsiveness to FSH parallels ovarian functions, being maximal during the ovulatory period. The ovarian sensitivity to FSH is also related to oocyte growth and vitellogenesis. Northern blot analyses reveal that the FSH receptor mRNA is maximally expressed in vitellogenic oocytes during the reproductive period. These results suggest that, in lizard ovary, hormone activation of adenylate cyclase is mediated by de novo synthesis of receptors specifically involved in FSH recognition. In lizards treated in vivo with FSH during the pre-ovulatory period, adenylate cyclase becomes refractory to further FSH stimulation 2 hr after treatment, but sensitivity to the hormone is restored after 2 weeks. Nevertheless, while the restored level of activity never exceeds that observed during the nonreproductive period, the expression level of FSH receptor mRNAs is significantly enhanced in these animals. These results suggest that in lizard the processes that regulate ovarian growth, vitellogenesis, and ovulation are controlled by a complex network of signals including gonadotropin, FSH receptor expression, and adenylate cyclase.
Adenylyl Cyclases↗
The inelastic neutron scattering spectrum of H3B:NH3 and the reproduction of its solid-state features by periodic DFT.
The inelastic neutron scattering (INS) and periodic density functional theory (DFT) vibrational spectra of H3B:NH3 are reported to 1600 cm-1. The H3B:NH3 structural and INS features, specifically the reduced solid-state B:N dative bond length and the altered B:N stretching frequency, are reproduced by the periodic DFT calculations, placing the B:N stretching mode at 800 cm-1, in excellent agreement with experiment relative to previous nonperiodic theoretical treatments of this molecule.
Journal Article↗
Changes in reproductive hormone secretion during the climacteric and postmenopausal periods.
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Aging↗
Blood flow through the reproductive organs in the hen during the maturation period and egg-laying cycle.
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Animals↗
[Effect of hydrocortisone on the reproduction of rat corneal epithelial cells at different periods of postnatal ontogenesis].
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Animals↗
[Effect of copulatory behavior at different periods of the ovarian cycle on ovulation and reproduction in the rat].
The effect of copulation on ovulation and reproduction during the diestrus, proestrus or estrus phases was compared by evaluating insemination, fertilization, number of embryos and ovulation. Copulation increases both ovulation and number of embryos per rat. This increase was significant when copulation occurred during the late of proestrus phase, mainly after the 16 hours of the proestrus phase. The copulation effect was lower during the late hours of diestrus and during the whole estrus phase.
Animals↗