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PubMed1982

Reproductive performance of totally confined sheep bred with semen extended in a lactose-egg yolk-glycerol buffer and stored at 5 degrees C.

Two experiments were carried out in January and May 1975 to study reproductive performance (fertility, prolificacy and fecundity) of totally confined sheep synchronized for estrus. The main objective of the first experiment was to compare reproductive performance of ewes bred naturally to those bred by artificial insemination. Semen for artificial insemination was collected by either artificial vagina or electroejaculation and stored for up to 36 hours at 5 degrees C. A second objective was to evaluate the effect of pregnant mares' serum gonadotrophin on the reproductive performance of ewes synchronized for estrus. Fertility was 53% for ewes bred by natural mating, 34% for ewes receiving pregnant mares' serum gonadotrophin and bred by artificial insemination, and 9% for those not receiving pregnant mares' serum gonadotrophin and bred by artificial insemination. There was no difference in fertility between ewes bred with semen collected by artificial vagina or by electroejaculation. A similar pattern was observed for fecundity. Average prolificacy was 2.0 with no significant differences among mating methods or pregnant mares' serum gonadotrophin application being observed. In the second experiment, the reproductive performance of ewes inseminated with semen stores at 5 degrees C for 48 to 60 hours was compared to that of ewes inseminated with semen stores for 24 to 36 hours. No significant differences in the reproductive performance were detected. Although average fertility (9%) and fecundity (19%) were low, prolificacy averaged 2.0 lambs per ewe lambing.

Animals↗
PubMed1995

Involvement of thyroid hormones in seasonal reproduction.

This article reviews experiments performed to investigate the importance of thyroid hormones to the expression of the seasonal reproductive cycle of ewes. Thyroidectomy was found to block the transition from the breeding season to anoestrus and to cause ewes to exhibit oestrous cycles all year round. Mechanistically, thyroidectomy produced this effect by preventing the seasonal increase in responsiveness to the negative feedback action of oestradiol on episodic GnRH secretion, thus interfering with a key neuroendocrine process necessary for anoestrus to develop. This response to thyroidectomy was fully prevented by replacement with physiological concentrations of thyroxine. Furthermore, the reproductive response to thyroidectomy was specific to the mechanisms that lead to anoestrus; other aspects of reproductive neuroendocrine function and seasonal and photoperiodic mechanisms were not affected. Evidence is presented to indicate that thyroid hormones have a permissive mode of action on seasonal reproduction, and that their effect is exerted during a restricted 'window' of time during the year. It is concluded that thyroid hormones play a crucial role of physiological significance to generation of the seasonal reproductive cycle of ewes.

Animals↗
PubMed1995

Research on human reproduction and the United Nations.

The Special Programme of Research, Development and Research Training in Human Reproduction was established in 1972 by the World Health Organisation to promote, co-ordinate, support, conduct and evaluate research on human reproduction with particular reference to the needs of developing countries. Today, the Programme is the main instrument of reproductive health research in the United Nations System. In addition to advising member state governments, the Programme supports research and development activities in the areas of technology assessment, development, introduction and transfer, epidemiological and social science research on reproductive health and essential national health research. Another important area of activity consists of strengthening the research capability of developing countries to enable them to address reproductive health problems of national relevance.

Demography↗
PubMed1995

Reproductive health in the American workplace.

Helping workers understand their risk of reproductive and developmental hazard exposure can be demanding for the occupational health nurse. The lack of conclusive information about most suspected hazards, as well as concern over job security and advancement, make this issue doubly challenging. Further research is needed to verify or rule out the suspected toxic effects of a hazard. The occupational health nurse must make every effort to keep abreast of new research findings and federal or state requirements related to reproductive hazards. The key to promoting the reproductive health of American workers is primary prevention (Bernhardt, 1990). Educating and counseling workers about reproductive hazards so that they can make informed decisions about their reproductive health, along with implementing engineering controls or ergonomic changes to reduce the risk of exposure, should be the goal of all occupational health programs.

Female↗
PubMedDate not supplied

Workplace policy on hazards to reproductive health.

At present, workplace policies regarding reproductive hazards are not regulated directly, and inappropriate policies are occasionally corrected by legal actions or union pressures on the employers. Further, information on reproductive hazards is incomplete; however, employees have a legal right to know available information about hazards, including reproductive hazards, that they face in the workplace. Occupational health personnel play a major role in communicating information about reproductive hazards in the workplace and in implementing company policy and complying with legislation. Regulatory and case law likely will continue to evolve as many issues related to safety from reproductive hazards in the workplace have not yet been resolved.

Ethics, Medical↗
PubMed1994

Clinical and research applications of real-time ultrasonography in bovine reproduction: a review.

Transrectal real-time ultrasonography has proved to be a rapid and reliable technique for studying reproductive functions in cattle. Through ultrasonography it is now established that follicular growth occurs in wave-like patterns during each estrous cycle. It has been shown that follicular growth and regression continue during early pregnancy, as well as in the postpartum anestrous period. Ultrasound has also helped us to understand the influence of dominant follicles on medium and small follicles. Among the numerous demonstrated applications of ultrasonography, early pregnancy diagnosis, fetal sexing, and postpartum reproductive management appear to be promising areas for immediate application. The new information that has been generated through ultrasound has thrown light on hitherto poorly understood areas of ovarian follicular dynamics, corpus luteum function, pregnancy establishment, and embryonic development in cattle, thereby opening newer areas for research. Still there is great potential for the continued application of this technology to further our understanding of the reproductive processes and to maximize reproductive efficiency of the bovine species. The significant contributions of real-time ultrasonography to the study of bovine reproduction in general and its practical applications in particular are discussed in this paper. The need for taking up technology assessment studies and for the introduction of low-cost portable equipment are stressed. Literature search for this review was done by scanning Current Contents Series 1991-92, AGRICOLA 1980-92, and MEDLINE 1990-92.

Animals↗
PubMed1993

Neuroendocrine ageing: its impact on the reproductive system of the female rat.

Numerous changes occur with age at all levels of the reproductive axis. Clearly, changing ovarian function plays a critical role in the cessation of reproductive cycles. Likewise, many changes in the function of neurotransmitters, gonadotrophin-releasing hormone and gonadotrophin itself appear to contribute to the ageing of the reproductive axis. It appears that the effects of ageing on neural time-keeping mechanisms may be important in the cascade of events that lead to reproductive dysfunction. The use of modern neurobiological and molecular methods to assess neural function within small regions of the brain should deepen our understanding of the complex interactions between neuroendocrine systems that underlie female reproductive cycles and cause them to change with age.

Aging↗
PubMedDate not supplied

Exposure to sublethal levels of waterborne lead alters reproductive behavior patterns in fathead minnows (Pimephales promelas).

Lead (Pb) caused multiple effects on reproductive behavior and overall reproductive success. Adult fathead minnows (Pimephales promelas) were acclimated at a 16L:8D photoperiod to stimulate reproductive development. Reproductively mature adults were separated as male-female pairs and maintained for 4 weeks in either 0.0 or 0.5 ppm Pb. High lead accumulations occurred in testes and ovaries of treated fish; lead concentrations in control fish gonads were not detectable. Lead suppressed spermatocyte production and retarded ovarian development, although no lead-induced gonadosomatic index changes for either sex were noted. Lead decreased the number of eggs oviposited, increased interspawn periods and suppressed embryo development. Control males displayed maximum secondary sex characteristic development (banding, tubercle formation, head and eye darkening); lead-exposed fish displayed less. Control males spent more time in ceiling-directed behaviors associated with nest preparation and maintenance than lead-exposed. These variables were affected differentially with respect to stage of reproductive maturity at time of lead exposure, i.e., fish displaying greater secondary sex characteristic development before exposure were less affected by lead than those fish that showed less development.

Animals↗
PubMed1993

Reproductive risks from contaminants in drinking water.

Reproductive toxicity is a complex subject which, besides birth defects or sterility, includes adverse effects which may be less readily observed but more relevant to chronic low-level exposures (e.g., impaired functional development of target organs or systems, secretion of toxic chemicals in maternal milk). Sodium chlorite, when present at high concentration, may be related to impaired reproduction; among water chlorination by-products, further research is required on the developmental toxicity of chloroacetic acid and dichloro- and trichloro acetonitrile. Among the water pollutants which may pose significant developmental hazards, risk assessments have been performed for nitrates/nitrites, fluorides and lead. Molinate (a herbicide), dibromochloropropane (a nematocide) and the halogenated contaminants ethylene dibromide and epichlorohydrin show an almost selective male reproductive toxicity, although they are likely to pose a risk mainly at occupational exposure conditions. Ethylene thiourea, an environmental metabolite of some fungicides is markedly teratogenic in the rat: however, other toxic effects are induced at levels of exposure significantly lower than the teratogenic ones. Such poorly water-soluble compounds as TCDD or hexachlorobenzene also need to be considered, because of their remarkable potentials for reproductive toxicity. Finally, it should be noted that the data on reproductive toxicity for a number of chemicals do not allow a risk assessment at present: this holds true also for some substances which might pose concerns on the basis of their levels in drinking water (e.g. tetrachloroethylene, nickel). Another area which deserves more attention is the investigation of the possible interactions of several contaminants present together at low levels.

Animals↗
PubMed1993

Gonadotropin-releasing hormone-containing neurons change size with reproductive state in female Haplochromis burtoni.

In the preoptico-hypothalamic area (POA) of teleost fish, neurons containing gonadotropin-releasing hormone (GnRH) regulate reproduction through direct projections to pituitary gonadotropes. Here we show that these GnRH-containing cells change size depending on the reproductive and maturational state in female Haplochromis burtoni. We selected animals prior to, during, and after the reproductive portion of their life history, in both brooding and spawning states. Immunocytochemical staining of GnRH-containing neurons in the POA revealed that these cells are up to twice as large in females that have never spawned or are in the act of spawning than they are in females that are carrying broods. Older, postreproductive females have the largest cell sizes. Previous work on male H. burtoni has shown that soma sizes of the homologous neurons change according to social status, with dominant fish having larger cells than subordinates. Since reproductively active females have no apparent social hierarchy and are all exposed to approximately the same external stimuli, the primary factor(s) controlling GnRH-immunoreactive (irGnRH) neuron size appears to be internal reproductive state. Thus, while irGnRH neurons are pleiomorphic in both males and females, cell size change is differently regulated in each.

Animals↗
PubMed1996

Race, genetics, and human reproductive strategies.

The international literature on racial differences is reviewed, novel data are reported, and a distinct pattern is found. People of east Asian ancestry and people of African ancestry average at opposite ends of a continuum, with people of European ancestry averaging intermediately, albeit with much variability within each major race. The racial matrix emerges from measures taken of reproductive behavior, sex hormones, twinning rate, speed of physical maturation, personality, family stability, brain size, intelligence, law abidingness, and social organization. An evolutionary theory of human reproduction is proposed, familiar to biologists as the r-K scale of reproductive strategies. At one end of this scale are r-strategies, which emphasize high reproductive rates; at the other end are K-strategies, which emphasize high levels of parental investment. This scale is generally used to compare the life histories of widely disparate species, but here it is used to describe the immensely smaller variations among human races. It is hypothesized that, again on average, Mongoloid people are more K-selected than Caucasoids, who are more K-selected than Negroids. The r-K scale of reproductive strategies is also mapped on to human evolution. Genetic distances indicate that Africans emerged from the ancestral hominid line about 200,000 years ago, with an African/non-African split about 110,000 years ago, and a Caucasoid/Mongoloid split about 41,000 years ago. Such an ordering fits with and explains how and why the variables cluster.

Biological Evolution↗
PubMed1997

Standard values for reproductive and clinical chemistry parameters of Japanese quail.

Historical control data of Japanese quail collected from reproduction studies conducted at the Federal Institute for Health Protection of Consumers and Veterinary Medicine between 1988 and 1994 are presented in this paper. Reproductive and clinical chemistry data from control animals of 10 ecotoxicological studies are summarized and discussed to develop a normal data base of this species. The data obtained were compared to the control reproductive parameters of bob-white quail and mallard ducks available in the literature. For a long time these two species have been most used in avian reproductive toxicology studies. In summary, the data obtained indicate that Japanese quail appears to be more appropriate to be used for the determination of reproductive effects of pesticides on birds.

Animals↗
PubMed1997

Socioeconomic differences in reproductive behaviour.

There are marked socioeconomic variations in the risk of female reproductive cancers. We examine here data from the World Fertility Surveys, the Demographic and Health Surveys, and other national surveys, to assess whether these variations in cancer risk might be explained, at least in part, by socioeconomic variations in reproductive behaviour. There were marked socioeconomic differentials in achieved parity, age at first birth, final childlessness, duration of breastfeeding, and possibly also age at menopause. These differentials were present in almost all settings: countries with low and high levels of modernization, and countries with low and high levels of fertility. In general, women of higher socioeconomic status and with more education had lower fertility and later age at first birth, but a greater prevalence of childlessness, shorter duration of breastfeeding and later age at menopause. However, the size and even the direction of these differentials varied markedly from country to country according to its level of economic development and, within each country, from generation to generation of women. It is possible that some of these socioeconomic differences may be narrowing in recent generations in Western countries. There was little evidence of socioeconomic variations in age at menarche. The observed socioeconomic differentials in most aspects of reproductive behaviour could potentially account for some of the socioeconomic variation in the risk of female reproductive cancers. However, this relationship could not be assessed directly because such analysis would require birth-cohort-specific data on socioeconomic variations in reproductive behaviour and in cancer risks. Unfortunately, these data are not available.

Adult↗
PubMed1998

Effects of p,p'-DDE on male reproductive organs in peripubertal Wistar rats following a single intraperitoneal injection.

The effects of p,p'-DDE on male reproductive organs were investigated in detail in peripubertal Wistar rats following a single intraperitoneal injection. 220 mg/kg of p,p'-DDE (1/4 of LD50) were injected once into prepubertal and postpubertal Wistar rats and its effects were observed until 20 weeks of age. Weights of the body and reproductive organs in p,p'-DDE-injected rats were similar to those in control rats, who were injected with corn oil only. Sperm profile parameters such as spermatid number within the testis, sperm number within the epididymis, sperm motility and its morphology were not different between the prepubertal or postpubertal p,p'-DDE-exposed group and the control group. Like-wise, the histopathological examination at stage VII of the seminiferous epithelium cycle, when the germ cells are sensitive to testosterone, was similar in all three groups during the observation period. Serum levels of testosterone also showed no significant changes by exposure to p,p'-DDE under the conditions of this study. From these results, the antiandrogenic or estrogenic activity attributed to p,p'-DDE was not confirmed in male reproductive organs and no impairment of sperm profile was observed. This study confirmed that the reproductive functions of matured animals are scarcely affected by p,p'-DDE exposure during the peripubertal period and revealed that they might be relatively resistant to exogenous endocrine-disrupting chemicals. p,p'-DDE may threaten the hormonal equilibrium required for normal gonadal development during the organogenesis period, at an earlier stage of life. Further studies are necessary to fully reveal all the effects of p,p'-DDE on male reproductive organs and sperm profile.

Animals↗
PubMed2006

Infertility, assisted reproduction and rights.

The rights to reproduce and found a family are recognized as basic human rights. Infertile couples should enjoy the same right to reproduce as those who have the ability to do so without assistance. Both positive and negative rights to access to assisted reproductive technologies are required in order to fully realize the reproductive rights. However, there is a limit to such a claim. The positive right of individuals to have state-funded assisted reproductive treatments has to be balanced against the provision of other societal goods and healthcare rationing. The negative right to acquire access to assisted reproductive technologies by individuals' own resources is also restrained. The barrier to such access is often of a moral nature, the standard of which depends on the values of the society.

Female↗
PubMed2004

A survey of the practices and opinions of the domestic members of the American Society for Reproductive Medicine.

OBJECTIVE: To learn how the domestic members of the American Society for Reproductive Medicine (ASRM) use its services and to survey their opinions regarding clinical practices and research in reproductive medicine. DESIGN: A self-administered mail survey. SETTING: Members of a professional organization. SUBJECT(S): A total of 1,291 members responded. Of these, 80% were physicians, embryologists, or nurses. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Demographics, use of ASRM services, and opinions. RESULT(S): Eighty-five percent of the respondents provided some type of clinical care for individuals with fertility problems. Two thirds read the ASRM News, and more than half used ASRM Practice Committee statements, Ethics Committee opinions, and patient education materials. Eighty-three percent reported that they followed the Ethics Committee opinions. Whereas 78% did not support reproductive cloning, two thirds supported somatic cell nuclear transfer to produce stem cells for research. The majority opposed governmental regulation of assisted reproductive technologies. CONCLUSION(S): The domestic membership of the ASRM is diverse in terms of demographics, practices, and opinions. In addition, they find the services of the ASRM to be of value.

Attitude of Health Personnel↗
PubMed1997

Gender and social differences in adolescent sexuality and reproduction in Nicaragua.

PURPOSE: The aim of this research was to study gender and social differences in adolescent sexuality and reproduction, as reflected in age at first intercourse and age at first pregnancy, as a basis for future interventions in the municipality of León, Nicaragua. METHODS: In a community-based cross-sectional study including 7789 households, all women aged 15-49 years (n = 10,867) were interviewed about socioeconomic, sexual, and reproductive issues. A random subsample of men (n = 388) and women (n = 413) aged 15-49 years was interviewed in more detail about sexual patterns and reproduction. RESULTS: The median age at first intercourse for women and men was 17.8 and 16.2 years, respectively. Women's average latency period to end of first pregnancy was 22 months. There was a significant tendency to start active sexual life later among today's girls aged 15-20 years, compared to the groups 21-27, 28-35, and 36-49 years old. A similar trend was found in age at first pregnancy. These secular trends were not found among men. Age at first pregnancy for current adolescents was lower among those having less formal education. CONCLUSIONS: The short latency period between first sexual intercourse and end of first pregnancy, probably reflecting lack of access to counseling and contraception, is worrying in light of the growing sexually transmitted disease/human immunodeficiency virus threat. The secular trend of later start of reproduction, however, is a positive sign which partly may be an effect of increasing education in the Nicaraguan society.

Adolescent↗
PubMed2000

What husbands in northern India know about reproductive health: correlates of knowledge about pregnancy and maternal and sexual health.

Women in India suffer from a high incidence of reproductive disease, disability and death. Very little work has been done on men, but a much higher incidence of sexual experience outside marriage and sexually transmitted diseases (STDs) among males than previously expected for this population is now being documented. In north India, women are dependent on their husbands and other family members for health-related decisions. Therefore, the behaviour, knowledge and attitudes of men are integral to the reproductive health status of couples there. This study explores knowledge about three distinct areas of reproductive health among 6549 married men in five districts of the northern state of Uttar Pradesh, India. Factors contributing to men's knowledge in the areas of fertility, maternal health and STDs were investigated. Results showed that very few men had basic knowledge in any of these areas. The likelihood of reporting knowledge was associated with a set of determinants that differed in their magnitude and effect across the areas of reproductive health explored. In particular, men's belief about the ability of an individual to prevent pregnancy demonstrated an independent association with men's knowledge. After controlling for factors such as age, parity and educational and economic status, men who believed it not possible to prevent a pregnancy were less likely to know when during the menstrual cycle women would become pregnant and certain facts about STDs, but they were more likely to be able to name two or more symptoms of serious maternal health conditions. Possible explanations for this trend are discussed.

Adolescent↗