SEARCH · PubMed Health

Results for “Reproductive Period”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMedDate not supplied

[The spatial relationships and social structure of gerbils in the genus Meriones (Gerbillinae, Rodentia)].

Comparative analysis of spatial relations of 4 gerbil species (M. tamariscinus M. meridianus, M. libycus, M. unguiculatus) shows differences in the system of space use between species and within a species--between individuals of different sex. During reproduction period females are inclined to isolation, small overlap of home ranges and high degree of individualisation. Males occupy large home ranges overlapping with territories of several reproductive females. The territories occupied by the males of midday and tamarisk gerbils do not have clear boundaries and the level of their individualization is quite low. The males of Mongolian gerbil (M. unguiculatus) occupy well defined territories with high level of individualization. Spatial relations of M. libycus males are intermediate. The relationships of the males of three investigated species (M. meridianus, M. libycus, M. tamariscinus) being characterised by the high degree of asymmetry of pair connections, are organised according to the principle of agonistic dominance. Relationships between individuals of different family groups of Mongolian gerbils are based on the locus-dependent dominance, while within one family group-on principle of hierarchical subordination. The meaning of specific peculiarities in use of space and dominance relations are discussed in terms of reproductive strategies.

Aging↗

PubMed1973

Nutrition and development of infants from poor rural areas. III. Maternal nutrition and its consequences on fertility.

To test the hypothesis that malnutrition alters fertility, the reproductive pattern of a poor rural community with a high natality rate was studied. A late menarche age (15.5 +or- 1.5 years) and an early menopause (40.4 +or- 2.5 years) were found and resulted in a short reproductive period of 25 years. In all, there were 8.8 +or- 2.7 pregnancies and 7.9 +or- 2.9 deliveries during this period, but only 4.8 +or- 2.2 children reached adulthood. A longitudinal observation was made of 2 groups which were similar in all respects, except that one was supplemented and the other was not. Both groups lactated the entire time between pregnancies as well. The control group recovered fertility 14.0 +or- 4.0 months after delivery while the supplemented group did after only 7.5 +or- 2.6 months; this difference, as well as the difference in recovery times in the experimental group before and after supplementation, were highly significant (P0.001). It may be concluded that undernutrition reduced mothers' fertility in 2 potential ways. It may reduce a woman's reproductive life and it determines an increase in the period between deliveries of more than 40%. Therefore, the high natality rate in this community should not be explained by high individual fertility but rather by the sociocultural characteristics of the community.

Americas↗

PubMed1997

Seasonal courses of CO(2) exchange and carbon balance in fruits of Cinnamomum camphora.

Carbon dioxide exchange in fruits of Cinnamomum camphora Sieb. was followed over a growing season from July to December 1992. Dark respiration was exponentially related to temperature, with a Q(10) value near 2. Light dependence of photosynthetic CO(2) refixation, i.e., the ratio of gross photosynthesis to dark respiration, was approximated by a hyperbolic function. Seasonal variation in maximum CO(2) refixation capacity ranged between 52 and 174%, reaching a maximum in early August. Daily photosynthetic CO(2) refixation ranged between 17 and 51% over the growth period. We evaluated seasonal variation in translocation rate to the fruit on the basis of the seasonal rates of gross photosynthesis, dark respiration and increase in fruit dry weight, and used the results to develop a simple carbon flow model of fruit development. Seasonal changes in translocation rate paralleled those in fruit growth rate, with two peaks during the periods before and after September. Seed formation took place in the period between the two peaks. The relationship between fruit growth rate and translocation rate was approximated by a linear function. The carbon flow model estimated that, over the reproductive period, the amount of assimilate translocated to each fruit was 377.2 mg dry weight, of which 58.5% was accounted for by weight growth and 41.5% was consumed by net respiration. Carbon dioxide refixation accounted for 22.9% of the carbon balance of the fruit.

Journal Article↗

PubMed2000

[Gynecological consultations for young females for treatment of sexual organ disorders].

The authors presented their consultations with young females at the out-patient clinic from 1983-1995 and compared them with their consultations during an earlier period. According to the authors, the frequency and character of the issues consulted changed as a result of a greater need for this type of help in general. The authors stressed the particular role of establishing thorough medical case histories on the gynaecology of the pubescent period. They concluded that effective child and pubescent female gynaecology could, in nearly every case, protect the patient against disorders and complications during in maturity and over the reproductive period.

Adult↗

PubMed2004

Effect of pregnancy on survival in women with cutaneous malignant melanoma.

PURPOSE: An adverse influence of pregnancy on the risk of death in women with cutaneous melanoma was suggested historically by anecdotal reports. Previous studies included small numbers of women observed for short periods. METHODS: Using data from the Swedish National and Regional Registries, we performed a retrospective cohort study of all Swedish women who were diagnosed with cutaneous melanoma during their reproductive period, from January 1, 1958, to December 31, 1999. The relationship between pregnancy status at the diagnosis of melanoma and overall survival was examined in multivariable proportional-hazards models. RESULTS: The cohort comprised 185 women (3.3%) diagnosed with melanoma during pregnancy and 5,348 (96.7%) women of the same childbearing age diagnosed with melanoma while not pregnant. There was no statistically significant difference in overall survival between pregnant and nonpregnant groups (log-rank chi(2)1[r] = 0.84, P = .361). Pregnancy status at the time of diagnosis of melanoma was not related to survival in a multivariable Cox model in the 2,101 women (hazard ratio for death in the pregnant group was 1.08; 95% CI, 0.60 to 1.93). In the multivariable analysis, pregnancy status after diagnosis of melanoma was not a significant predictor of survival (hazard ratio for death in women who had pregnancy subsequent to the diagnosis of melanoma was 0.58; 95% CI, 0.32 to 1.05). CONCLUSION: The survival of pregnant women with melanoma is not worse than the survival of nonpregnant women with melanoma. Pregnancy subsequent to the diagnosis of primary melanoma was not associated with an increased risk of death.

Adult↗

PubMed1986

Reproduction of the male eastern pipistrelle, Pipistrellus subflavus, in the north-eastern United States.

The major reproductive events in the male eastern pipistrelle, are similar to those of other hibernating vespertilionids. The eastern pipistrelle stores epididymal spermatozoa throughout hibernation, a time when the testes are involuted but accessory gland activity is maintained. However, this species differs from others in that epididymal and testicular spermatozoa persist longer and the weights of the accessory glands are not strongly differentiated between winter and spring/summer. It is suggested that the reproductive period is extended in this species as a function of a more prolonged period of hibernation, resulting in only a brief period of sexual quiescence in mid-summer. The eastern pipistrelle (Pipistrellus subflavus) resembles the canyon bat (P. hesperus) in that some testicular spermatozoa persist during winter. Many aspects of the reproductive anatomy and chronology of these two species are similar; however, eastern pipistrelles apparently lack a seminal vesicle and possess a distinctly different baculum.

Animals↗

PubMed1976

The association of semen traits and fertility in the turkey.

There were no significant correlation coefficients between semen traits (yield, concentration and frequency of bent sperm) measured prior to the first insemination and fertility over a 12-week hatching period when the amount of semen inseminated per female was greater than the minimum (.025 cc.) usually recommended. Although there were some statistically significant correlations between semen measurements made later in the reproduction period and fertility for the entire period, they were very small ranging from -- .29 to +.20.

Animals↗

PubMed1997

Effects of androgens on male sexual behavior and secondary sex characters in the explosively breeding spadefoot toad, Scaphiopus couchii.

In male Scaphiopus couchii, plasma elevations in androgens are associated with the seasonal expression of sexual behavior. To test the hypothesis that androgens are necessary for the expression of one aspect of sexual behavior, amplexus, and for the development of secondary sex characteristics in male S. couchii, the effects of testosterone (T) and dihydrotestosterone (DHT) on clasping behavior and thumb pad growth were investigated. Forty toads were divided into five treatment groups as follows: (1) intact, with no hormonal or surgical treatment; (2) sham-castrated, with silastic implants of cholesterol; (3) sham-castrated, with implants of T and DHT; (4) castrated, with implants of cholesterol; and (5) castrated, with implants of T and DHT. Displays of sexual behavior (amplexus) for each individual were counted during a 3-hr observation period at 2, 4, and 7 weeks after the surgical procedure. For each observation trial, there was no significant difference in the amount of clasping among treatment groups: virtually all individuals from each group displayed vigorous clasping. No calling was noted at any time. Thumb pad darkness of each individual was assessed at the 4- and 7-week time intervals. At both time periods, the thumb pads of androgen-treated males were significantly darker than those of cholesterol-treated males, while intact males remained intermediate. Measurement of plasma steroid levels from the treatment groups indicated that androgens were basal in the castrate group and higher in the implant treatment. These results suggest that in S. couchii, although androgens are associated temporally with the onset of reproductive behavior, they are not necessary for its expression. The elevation in androgens during the reproductive period may be instead important in the development and maintanence of secondary sex characteristics and possibly other reproductive functions.

Androgens↗

PubMed1991

Chronic toxicity of a pure and technical grade pentachlorophenol to Daphnia magna.

Chronic toxicity test procedures (static, with renewal) were used to determine the chronic toxicity of sublethal concentrations of a technical formulation of pentachlorophenol (PCP) and pure pentachlorophenol to Daphnia magna. Test organisms 48 +/- 12 h old were exposed for their entire lifespan (i.e., until death) to 0.01, 0.05, 0.1 and 0.5 mg technical PCP/L and 0.01, 0.087 and 0.1 mg pure PCP/L. Criteria used to assess chronic toxicity were mean time to appearance of the primiparous instar in the brood chamber, mean number of days to release of the first brood, mean number of broods produced per female, mean brood size per female, mean number of reproductive days, mean number of young produced per reproductive day per female and survivorship. Pentachlorophenol differentially affected maturation and reproduction but not survivorship or longevity. Mean number of broods produced per daphnid, length of the reproductive period, longevity and survivorship were insensitive criteria relative to mean time to appearance of the primiparous instar, time to release of first brood, brood size, and number of young produced per daphnid per reproductive day. Generally, there was little difference in toxicity of the three concentrations of pure PCP, for they significantly reduced mean brood size and rate of reproduction of young and significantly but differentially affected maturation. Technical PCP, at the highest concentration of 0.5 mg/L, significantly reduced mean brood size and the rate of production of young, and significantly delayed both time to appearance of the primiparous instar and release of the first brood. When differences in toxicity occurred, generally, pure PCP was more toxic than comparable concentrations of technical PCP. Although enhanced maturation was observed there was no compensatory reproduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

[The effect of chronic ionizing radiation at low doses on a number of reproductive indices in CC57W/Mv mice from an experimental Chernobyl population].

The effects of low doses of environmental ionizing radiation on reproductive functions of seven generations of CC57W/Mv mice from Chernobyl experimental population has been investigated. A decrease in the number of litters per female during reproductive period, the number of newborn animals per litter, and an increase in the postnatal mortality during the first month of life were shown. These effects are due to the stable disorders of parental reproductive system and the high level of in-vivo preimplantation deaths in F1--F7 generations of CC57W/Mv mice from the Chernobyl experimental populations.

Animals↗

PubMed1987

[Inversion polymorphism in the malaria mosquito Anopheles messeae. VII. Fertility and the population genetics structure of the species].

The role of chromosomal inversional complexes of different fecundity has been studied in the process of formation of karyotypic populational structure. Females with homozygotes 2R11 and "north-est" inversional combinations are shown to have maximal total egg production, while females with three or four inversional heterozygotes from XL01, XL12, 2R01, 3R01 and 3L01 demonstrated lower level of fecundity. It is found that the seasonal conversion from r-selection to K-selection occurs in the period of population "prosperity" (July). The results of such conversion are destruction of "northest" genocomplexes and reduction of relative fecundity of inversional homozygotes 2R11-Alternative tendencies take place at the beginning of the reproductive period.

Animals↗

PubMed1989

[Resistance to drought of mollusks of the genus Bulinus, vectors of human and animal trematode infections in Senegal. II. Study under natural conditions in the North-Sudan area. Ecology and resistance to drought of Bulinus umbilicatus and B. senegalensis].

The authors report on the results of a 2-year study on the ecology and resistance to drought of B. umbilicatus and B. senegalensis on 3 temporary ponds in the North-Sudan area (region of Tambacounda, Senegal). The variations in some abiotic factors like the temperature and the pH of water do not seem to have a strong influence on the ecology while rainfall has a great importance on the distribution and the density of molluscs. As a fact, the quantity of water and the drying out period of these ponds depend upon rain factors which rule the existence and the survival of the malacological fauna. In the second part of the rainy season, the population reaches its maximum, i.e., during the reproduction period. Monthly observations show that the relative abundance of B. umbilicatus is higher than that of B. senegalensis. These ponds are dry during 6 to 8 months per year. However the populations of molluscs regenerate regularly, a fact which presupposes a certain ability to resist drought. Some come through this period successfully, but the middle-sized ones (7 to 9.9 mm) resist better than others (70 to 80 per cent of the population). Immediately after the first rains they resume their activity and lay intensively in order to reconstitute the population. B. umbilicatus and B. senegalensis are potential intermediate hosts for human and animal trematode infections, but in the studied region only B. umbilicatus intervenes in the transmission of S. haematobium and S. curassoni which occurs between September and November. Under natural Sahel conditions the epidemiological cycle is short and everything happens within 4 to 6 months with the regeneration and the growth of the population of molluscs, its infestation and the transmission of trematode infections. The ecological behaviour of these molluscs in the North-Sudan region is very important in the epidemiology of human and animal trematode infections and requires a new controlling strategy. The destruction of molluscs is more effective and more economic at the end of the rain season, which is the beginning of the drying of ponds, a period in which they concentrate in the residual water pools.

Animals↗

PubMed1989

Regulation of the onset of the breeding season of the ewe: importance of long days and of an endogenous reproductive rhythm.

Three experiments were conducted to evaluate the role that the increasing day lengths of late winter and spring play in timing the breeding season of the Suffolk ewe. In the first experiment, ewes were denied their normal complement of increasing day length by maintaining them on the photoperiod experienced at the winter solstice. This prevented the breeding season from occurring the subsequent autumn. In the second experiment, ewes were exposed to increases in day length at different time-intervals after the winter solstice: the normal time, later than normal or earlier than normal. Once the summer solstice photoperiod was reached, it was maintained until the end of the study. When increasing photoperiod was provided early, the breeding season was advanced; when it was provided late, reproduction was delayed. In the third experiment, ewes were exposed to a continuously increasing photoperiod matching the maximal rate of rise in natural conditions; this treatment was begun on the spring equinox and continued until mid-autumn. The steadily increasing photoperiod did not alter the time of reproductive onset in the autumn. These findings support the following conclusions for timing of the breeding season of the Suffolk ewe. (1) The lengthening photoperiod between the winter and summer solstices is required for the occurrence of the breeding season in the autumn. (2) The time of initial exposure to this lengthening photoperiod provides an important cue for determining when the reproductive period occurs. (3) The time of onset of the breeding season does not depend upon the decreasing photoperiod after the summer solstice, nor does it require the photoperiod to stop increasing as the summer solstice approaches. These findings have been incorporated into a conceptual model for temporal regulation of the annual reproductive cycle of the ewe. An important component of this model is a critical role for increasing photoperiod to initiate a process in the late winter-spring which ultimately leads to an obligatory reproductive onset in the autumn.

Animals↗

PubMed1980

Changes in plasma calcium, phosphorus, lipids, and estrogens in turkey hens with reproductive state.

Plasma calcium increased during the two weeks prior to first egg. The increase was in the protein bound (CaB) but not the ultrafilterable (CaU) fraction. Plasma neutral lipids (NL) and low density lipoprotein fraction (LDF, d < 1.006) increased similarly to CaB. Free fatty acids (FFA) had a transitory increase at first egg but then returned to levels not different from those when the hens were immature or in a reproductive pause. Plasma total phosphorus (Pt) increased similarly to CaB. This increase was associated with the protein (Pp) and lipid (Pl) phosphorus fractions. No change was noted for inorganic (Pi) phosphorus. Total plasma estrogen (Et), as estimated with radioimmunoassay utilizing an estriol antiserum, increaed similarly to CaB. Most of the increase was in an unidentified estrogen (Eu) fraction, but a sustained increase was also noted in the estrone (El) fraction. Estradiol (E2) levels did not differ with reproductive period. Simple correlations were calculated between all factors within the stimulatory and laying periods. In general, all correlations except those with diffusible calcium (CaD), FFA, and E2 were positive, relatively high (> .6) and significant (P < .01). The correlations tended to be greater in the stimulatory period than in the laying period. Partial correlations of the three estrogens with the other factors were calculated for the stimulatory and laying periods. The partial correlations of Eu were significant for all factors except CaD during the stimulatory period, but only with FFA, Pp and Pi in the laying period. The partial correlation of El with LDF was significant in the stimulatory period, and for LDF, NL, and Pi in the laying period. Partial correlations of E2 within the stimulatory period were not significant, but in the laying period a significant partial correlation with NL was noted.

Animals↗

PubMed2005

Hormonal control of the IGF system in the sea bream ovary.

Numerous studies have described the presence of an intragonadal IGF system involved in regulation of gametogenesis in teleost fish. In the present study, the in vivo effects of estradiol-17beta (E2) and growth hormone (GH) exposure on IGF-I, IGF-II, IGF1R, and IGFBP2 gene expression in sea bream ovary were monitored by RT-PCR during prereproductive and reproductive periods. The evidence demonstrates that both hormones investigated here affect the ovarian IGF system, showing that it is not only under GH control, but also can be regulated by sexual hormones; this hormonal modulation is related to reproductive phase.

Animals↗

PubMed1980

Influence of dietary protein during the pre-breeder period on subsequent reproductive performance of large white turkeys. 2. Growth, feed consumption, and male sex-limited reproductive traits.

the effect of low dietary protein during the rearing and breeding periods on the reproductive performance of Large White turkey males was examined. At 12 weeks of age 251 males were randomly divided into two groups and fed either 12 or 17% protein through 56 weeks of age. Body weight gains from 12 to 20 weeks and 20 to 28 weeks of age were significantly reduced for the males receiving the 12% dietary protein. However, after 28 weeks of age, weight differences decreased and by 56 weeks of age body weights of both groups were approximately the same. In addition, a significant reduction in feed consumption was noted for the males fed 12% protein. Males on the high protein diet experienced a higher mortality than those on the low protein diet. Low dietary protein reduced semen volume and spermatozoa concentration at 33 weeks of age, but there were no significant differences thereafter. The percentages of normal, abnormal, or dead spermatozoa were unaffected by dietary protein levels. Feeding 12% protein from 12 to 56 weeks of age to Large White turkey breeder males was adequate for high quality semen production.

Animals↗

PubMed1992

Fish consumption and reproductive outcomes in Green Bay, Wisconsin.

Prenatal exposure to polychlorinated biphenyls (PCBs) and reproductive outcome was determined in a population of 1112 women during 1987-1989. The women studied were from the Green Bay, Wisconsin area, thereby providing a population with potential PCB exposure from Lake Michigan sport fish consumption. All women with positive pregnancy tests from two Green Bay prenatal clinics were asked to complete a self-administered questionnaire on fish consumption, health and reproductive history, and other relevant issues and to provide blood samples for PCB analysis. A positive correlation was found between the amount of Lake Michigan fish mothers claimed to consume and their PCB serum levels. After the pregnancy period, reproductive outcome measures (fetal wastage; stillbirths; and birth weight, birth length, head circumference, ponderal index, and birth weight percentiles for live births) were abstracted from hospital labor reports. Typical negative associations between birth size measures and consumption of caffeine, smoking, and alcohol were found. Birth size was positively associated with gestational age, birth order, weight gain during pregnancy, male babies, and rural residence. Birth size was also associated with PCB exposure; however contrary to expectations, a positive association was found (P < 0.044) for most mothers (the exception being those mothers who gained more than 34 lb during their pregnancy). PCB exposures were lower than the other studies that found that birth size was negatively associated with PCB exposure.

Adolescent↗

PubMedDate not supplied

[Cestode egg production dynamics and fertility in Diphyllobothrium dendriticum (Cestoda, Pseudophyllidea)].

Dynamics of egg production of the tapeworm Diphyllobothrium dendriticum has been estimated experimentally in nestlings of the herring gull Larus argentatus per day and per reproductive period. The number of eggs in strobiles has been estimated for the maturation period. Mean egg production of the tapeworm per day (10.43 +/- 2.72 mln) is two orders of magnitude as high as the maximum number of eggs in a mature strobile (0.206 +/- 0.007). It is proposed to estimate coefficient of reproduction intensity as the ratio of egg output per unit of time and maximum egg number in a mature strobile.

Animals↗