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PubMed1989

Effect of Actinomyces pyogenes and gram-negative anaerobic bacteria on the development of bovine pyometra.

Fifteen lactating Holstein cows were used in a trial designed to evaluate the effectiveness of intrauterine inoculation (challenge) of Actinomyces pyogenes (A) alone or in combination with Fusobacterium necrophorum (F) and Bacteroides melaninogenicus (B) to induce pyometra. Cows were assigned to one of five groups: A (n = 3), AB (n = 3), AF (n = 3), ABF (n = 3) or C (control, broth medium alone; n = 3). All cows exhibited estrus 12 or 13 d prior to challenge (Day 0=first day of challenge). During the prechallenge period, the reproductive tract of each cow was palpated per rectum and uterine fluid aspirates for culture and uterine biopsies were also obtained. All cows received an intravenous injection of 5,000 IU of human chorionic gonadotropin (hCG; Day 5) and an intrauterine infusion of 40 ml of 0.7% iodine solution (Day 1). Cows were then inoculated on Days 0, 1 and 2 of the experiment. Sequential palpations of the reproductive tracts, samples of uterine fluid for culture and uterine biopsies were performed for a total of 30 d after the first inoculation. A cow was diagnosed as having pyometra when purulent uterine fluid and a corpus luteum were detected by palpation per rectum. The number of cows that developed pyometra in Group A was 2 of 3, in Group AB 3 of 3, in Group AF 3 of 3, in Group ABF 3 of 3 and in Group C 0 of 3. Cows with pyometra did not exhibit estrus. In 7 of 11 cows, pyometra persisted for more than 21 d. In cows that developed pyometra, the same species of bacteria infused into the uterus were usually recovered one or more times during the postchallenge period. When clinical pyometra was diagnosed, histologic endometritis was invariably present. Histologic endometritis and concurrent isolation of A . pyogenes alone or A . pyogenes with gram-negative anaerobic bacteria occurred in 91.7% of samples during the postchallenge period. Regardless of bacterial treatment, gram-negative anaerobic bacteria were frequently isolated with A . pyogenes during this period.

Journal Article↗

PubMed2006

Developmental exposure to environmental endocrine disruptors: consequences within the ovary and on female reproductive function.

Female reproductive function depends upon the exquisite control of ovarian steroidogenesis that enables folliculogenesis, ovulation, and pregnancy. These mechanisms are set during fetal and/or neonatal development and undergo phases of differentiation throughout pre- and post-pubescent life. Ovarian development and function are collectively regulated by a host of endogenous growth factors, cytokines, gonadotropins, and steroid hormones as well as exogenous factors such as nutrients and environmental agents. Endocrine disruptors represent one class of environmental agent that can impact female fertility by altering ovarian development and function, purportedly through estrogenic, anti-estrogenic, and/or anti-androgenic effects. This review discusses ovarian development and function and how these processes are affected by some of the known estrogenic and anti-androgenic endocrine disruptors. Recent information suggests not only that exposure to endocrine disruptors during the developmental period causes reproductive abnormalities in adult life but also that these abnormalities are transgenerational. This latter finding adds another level of importance for identifying and understanding the mechanisms of action of these agents.

Animals↗

PubMed1995

Influence of the opposite sex on photoperiodically induced LH and gonadal cycles in willow tit (Parus montanus).

In early January photosensitive willow tits (Parus montanus) were transferred from natural to long days (20L;4D). The study included three groups of birds: one group consisted of pairs (one male and one female kept together in a cage), a second group consisted of males, and a third group included only females. Birds from the separate groups could neither see nor hear each other. Gonadal and LH cycles were followed over a 2-month period. The reproductive systems of male and female willow tits were activated by the long day exposure. This response was, however, affected by the presence/absence of a mate. Ovarian follicles in females caged together with a male grew faster than did follicles in females kept alone in their cages. Ovarian regression started at the same time in both female groups. Contrary to females, gonads in males caged together with females grew slower and also regressed much earlier than did tests in males kept alone. LH cycles differed only slightly between the two groups of females. In both groups maximum LH levels were reached already after 3 days of long day exposure. Maximum LH level was attained earlier in paired males (Day 3) than in single male (Day 7). Males without female company however maintained high plasma levels of LH for a much longer period of time (about 4-5 weeks) than did paired males. The observed differences are discussed in relation to the ecology of the willow tit.

Animals↗

PubMedDate not supplied

Coronary artery disease in women.

Although most women cite breast and reproductive cancers as the diseases they most fear, in fact cardiovascular disease is much more likely to kill them: 500,000 American women die each year of diseases of the heart and blood vessels compared with 189,000 who die of all cancers combined. Women's focus on breast, uterine, and ovarian cancer is very much socially and culturally determined. It reflects an outmoded image of women as valuable principally by virtue of their ability to bear and raise children. While women died at about the age of 48 at the turn of the century, biomedical science was extended their life span to the point that a girl born today has an average life expectancy of 86 years. The focus of recent biomedical investigation reflects the changing experience and expectations of women, who will live a full third of their lives beyond the period of reproductive viability. Since 1988, a flood of new information established that the epidemiology, risk factors, clinical features, outcome and therapeutic choices physicians make for female patients with cardiovascular disease are significantly different from those of men. Regrettably, most of the new information we have acquired was almost exclusively harvested from data on Caucasian women: black women often are less than 10% of study populations. The information we do have, however, shows striking differences between women of different races in the severity and outcome of diseases of the heart and blood vessels: black women have significantly higher mortality rates from stroke and myocardial infarction than do white women. Intensive research has achieved gratifying corrections in the promptness with which physicians diagnose women with cardiovascular disease and in the aggressiveness of the therapy they offer to female patients. The result has been a reversal of the trend for women to have worse outcomes from revascularization procedures than men.

Adult↗

PubMed1979

Male reproductive patterns in nonhibernating bats.

Knowledge relative to the reproduction of nonhibernating bats is reviewed. Events in the male, as they are now understood, are summarized for all families for which data exist. Attention is given to the wide species diversity of male accessory sex oragns in respect to gross structure and glandular complement. Stability or variability or organization of the male reproductive system is noted. Functional relationships between primary and accessory sex organs are considered and any synchrony between these organs and their functional cyclicity identified. Various frequencies of male reproductive cycles are examined for each species within families. Factors influencing male reproductive evens in nonhibernating Chiroptera are briefly considered. It has long been speculation that reproductive cycles under natural conditions are strikingly related to the environment, with such features as temperature, moisture, length of day and available food all implicated. These cues, however, appear to be filtered through varied genetic potential and physiological patterns, since not all species respond similarly, even though residing together in a homogeneous environment. Variation between certain species in frequency and length of the oestrous cycle seem to be accommodated to by parallel adjustments in the male, including extended sperm production or storage and continued secretory activity of accessory sex glands.

Animals↗

PubMed2001

Sex differences in plasma corticosterone in desert tortoises, Gopherus agassizii, during the reproductive cycle.

Blood samples from 30 female and 20 male adult desert tortoises, Gopherus agassizii, were collected at monthly intervals during the annual reproductive cycle (April to October). Plasma corticosterone and the sex steroids in each of the samples were analyzed by radioimmunoassay. Mean corticosterone levels in males were significantly higher than in females (P < 0.001) in every month. Male tortoises showed a marked seasonal pattern in plasma corticosterone with a highly significant peak in July, August, September, and October that corresponded with a similar peak in plasma testosterone. Testosterone and corticosterone in the male showed a highly significant correlation (P < 0.0001). The pattern of corticosterone in the female was less marked, with a significant peak in May during the mating and nesting season, but no association with the peak in estradiol in late summer was apparent. The highest levels of corticosterone in the males were associated with the peak in spermatogenesis and intense male-male combat. These results support similar data from other reptiles that suggest increased glucocorticoid secretion during periods of increased activity and metabolism.

Animals↗

PubMed2001

Developmental stage sensitivity and mode of action information for androgen agonists and antagonists.

The response from exposure to a toxic agent during development may vary depending on the dose, time of exposure and the mode of action. The mode of action and developmental stage sensitivity are established only for a limited number of chemical classes. Some aspects of developmental stage sensitivity that appear to affect the response to androgen agonists and antagonists are the levels and distribution of endogenous androgens and the androgen receptor at particular times during development. This information is summarized and discussed as it relates to two critical windows of development: the period of male reproductive tract differentiation, and the peripubertal period when male sexual maturation occurs. Developmental stage sensitivity and mode of action data for the androgen antagonist vinclozolin are reviewed. Vinclozolin acts by binding to and activating the androgen receptor and affects a number of endpoints of reproductive tract differentiation as well as pubertal maturation. Approaches to incorporating mode of action, developmental stage sensitivity, and dose/potency information into risk assessment, as well as the additional data needed for using mode of action information, both qualitatively and quantitatively, in risk assessment are discussed. These issues are also considered in the context of combining the risks of exposure to two or more chemicals with similar modes of action.

Aging↗

PubMed2000

Age-dependent changes in sperm production, semen quality, and testicular volume in the black-footed ferret (Mustela nigripes).

The black-footed ferret (Mustela nigripes), which was extirpated from its native North American prairie habitat during the 1980s, is being reintroduced to the wild because of a successful captive-breeding program. To enhance propagation, the reproductive biology of this endangered species is being studied intensively. The typical life span of the black-footed ferret is approximately 7 yr. Female fecundity declines after 3 yr of age, but the influence of age on male reproduction is unknown. In this study, testis volume, seminal traits, sperm morphology, and serum testosterone were compared in 116 males from 1 to 7 yr of age living in captivity. Results demonstrated that testes volume during the peak breeding season was similar (P > 0.05) among males 1 to 5 yr of age, reduced (P < 0.05) among males 6 yr of age, and further reduced (P < 0.05) among males 7 yr of age. Motile sperm/ejaculate was similar in males 1 to 6 yr of age but diminished (P < 0.05) in those 7 yr of age. Males at 6 and 7 yr of age produced fewer (P < 0.05) structurally normal sperm than younger counterparts; however, serum testosterone concentrations were not reduced (P > 0.05) in older males. Histological comparison of testicular/epididymal tissue from 5- and 7-yr-old black-footed ferrets confirmed that the interval between these two ages may represent a transitional period to reproductive senescence. In summary, functional reproductive capacity of male black-footed ferrets exceeds that of females by at least 2 yr. Testes and seminal quality are indistinguishable among males 1 to 5 yr of age, with progressive reproductive aging occurring thereafter.

Aging↗

PubMed1989

Simulated drought influences reproduction in male prairie voles.

The environmental factors that arrest breeding in prairie voles during the middle of the breeding season are unknown. The role of water availability on reproductive function was examined by limiting water intake to 50% of ad lib water consumption for 10 weeks. At autopsy, testicular, epididymal and seminal vesicle masses were reduced in water restricted males as compared to animals with ad lib access to water. Body mass was also reduced in water restricted males. Plasma testosterone levels and the number of testicular and epididymal sperm were significantly reduced in water restricted voles as compared to animals drinking water ad lib, but plasma levels of luteinizing hormone were unaffected. Taken together, these data suggest that reduced water availability can inhibit male prairie vole breeding.

Animals↗

PubMed1990

Photoperiod affects reproductive responsiveness to 6-methoxy-2-benzoxazolinone in house mice.

House mice (Mus musculus) have traditionally been characterized as nonphotoperiodic because reproductive function is unaffected by day length in the laboratory. In the present study, the reproductive responsiveness of CF1 mice to a naturally occurring plant metabolite was assessed in animals that were maintained in either long (16L:8D) or short (8L:16D) photoperiods from birth until the end of the study. Males and females were implanted i.p. with either an empty Silastic capsule or one containing 6-methoxy-2-benzoxazolinone (6-MBOA) at either 21 or 60 days of age for 3 days. Other 31-day-old mice were implanted with capsules for 8 wk. Three-day exposure to 6-MBOA stimulated uterine growth in short-day, adult females, but did not affect adult females housed in long photoperiods. Short-term treatment with 6-MBOA did not significantly affect reproductive parameters in either long- or short-day peripubertal house mice, or in adult males regardless of photoperiod, nor did exposure to 6-MBOA for 8 wk influence reproduction in males in either photoperiodic condition. However, short-day female mice had significantly reduced ovarian and uterine masses after 8 wk chronic 6-MBOA treatment as compared to long-day animals or mice unexposed to 6-MBOA. Short-day females exposed to 6-MBOA for 8 wk developed a denser pelage compared to long-day mice treated with this compound. Photoperiod-mediated differential responsiveness to 6-MBOA indicates that female house mice can discriminate long from short days, and these results suggest that the physiological mechanisms for photoperiodic responsiveness remain extant in this species previously characterized as nonphotperiodic.

Animals↗

PubMed2001

Identification and synthesis of male-produced sex pheromone components of the stink bugs Chlorochroa ligata and Chlorochroa uhleri.

The reproductive behaviors of the stink bugs Chlorochroa ligata and C. uhleri were studied in the laboratory. Adults of both species became sexually mature about 12-14 days after the final molt, and both sexes mated multiple times during their lifetimes. The mean duration of copulation was 54 +/- 24 min for virgin bugs and 46 +/- 33 min for experienced bugs for C. ligata and 78 +/- 55 min for field-collected C. uhleri of unknown mating status. Male C. ligata were found to transfer a significant fraction of their body mass (19%) to females during mating. Sexually mature C. uhleri males produced three sex-specific compounds, methyl (R)-3-(E)-6-2,3-dihydrofarnesoate, methyl (2E,6E)-farnesoate, and methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate, in a ratio of 100:0.9:0.6. These three compounds were also produced by sexually mature male C. ligata in a ratio of 100:0.5:0.4. Identifications of the compounds were confirmed by synthesis. Production of the male-specific compounds peaked in late afternoon to early evening, coincident with the peak period of reproductive activity. Laboratory and field bioassays demonstrated that female bugs were attracted to odors from live males and to reconstructed blends of the male-specific compounds.

Animals↗

PubMed2000

Seasonal adiposity and androstenedione production as a possible mechanism for asynchronous reproductive activity between males and females of vespertilionid bat, Scotophilus heathi.

Relationship between changes in the body weight and circulating androstenedione concentration was examined in order to find out their involvement in asynchronous gametic cycle of male and female S. heathi. Body weight of both male and female bats increased from September due to accumulation of white adipose tissue and reached to a peak in November. The body weight declined gradually due to consumption of adipose tissue during December and January reaching basal level in February. A significant correlation between body weight and serum androstenedione concentration was observed. Correlated with maximum body weight, peak androstenedione level was found during November in both male and female bats. Peak androstenedione level during November may be responsible for stimulating spermatogenesis in the male, but may suppress follicular growth and ovulation in the female, thus resulting in asynchronous gametic cycle of male and female S. heathi.

Adipose Tissue↗

PubMed1995

The influence of the reproductive cycle on levels of some metabolism indices in ewes.

Investigations were performed in 14 ewes of the Polish Merino race, undergoing the second reproductive cycle. Fundamental indices of the protein and energy metabolism, levels of Ca, P, Mg, Cu, Fe and beta-carotene as well as vitamins A, E and C in the blood plasma and serum were determined. The analyses were carried out during the following periods of the reproductive cycle: 3 weeks before mating, the early and late pregnancy, the culmination and close of lactation. The levels of metabolism indices, especially those of the protein and energy metabolism, were found to vary during the studied periods of the reproductive cycle. In all the periods, low levels (during lactation a deficiency) of Ca and Mg and a distinct deficiency of vitamin C were detected. It seems therefore, necessary to work out the reference values for particular periods of the reproductive cycle.

Animals↗

PubMed2004

Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilian Uraeotyphlus narayani (Amphibia: Gymnophiona).

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.

Amphibians↗

PubMed2005

Reproduction of Zoanthus sansibaricus in the infra-littoral zone at Taisho Lava Field, Sakurajima, Kagoshima, Japan.

In order to obtain data on the reproductive pattern of the clonal cnidarian Zoanthus sansibaricus, polyps were sampled by scuba gear at Taisho Lava Field, Sakurajima, for 24 months between April 2000 and March 2002 (polyps collected weekly for breeding season). According to cross-sections, Zoanthus polyps were divided into three sexual types; male, female and asexual, and were found in the same colony. At Sakurajima, Zoanthus sansibaricus spawned in the middle of July, releasing oocytes and sperm. These spawning events occur synchronously with moon phase. In gametogenesis of Zoanthus sansibaricus, oocytes became recognizable in February and grew rapidly from the end of June onward. Spermatocytes became recognizable in June and matured rapidly in the middle of July. After spawning events, oocytes still remaining in the endoderm were absorbed into Zoanthus tissue quickly.

Animals↗

PubMed1985

The role of rhythms in the response to melatonin.

Rhythmicity of melatonin secretion is critical to the regulation of mammalian reproduction by daylength. In the ewe, photoperiod determines ovarian function by modulating the ability of oestradiol to suppress pituitary secretion of luteinizing hormone (LH). This influence of daylength depends in turn upon the pineal gland, which mediates photic control of the frequency at which the brain stimulates the pituitary to secrete gonadotropin. Photoperiod determines the pattern of melatonin secretion, most notably setting the duration of the nightly elevation in serum concentrations. Replacement of melatonin in pinealectomized ewes drives responsiveness to oestradiol negative feedback; LH levels are determined by the duration of the nightly melatonin infusion rather than by the photoperiod to which ovariectomized, oestradiol-implanted pinealectomized ewes are exposed. Refractoriness to stimulatory and inhibitory photoperiods may reflect circannual modulation of the responsiveness of neuroendocrine mechanisms to melatonin signals of a given duration.

Animals↗

PubMed2004

Temporal variation of autonomic balance and diseases during circadian, seasonal, reproductive, and lifespan cycles.

Many diseases show patterns of temporal variation that remain unexplained. We hypothesize that oscillation of autonomic balance over different time intervals plays a role in these variations. In the Darwinian struggle, organisms must perform various functions related to fitness such as survival, energy acquisition, and reproduction in a prioritized fashion. Autonomic systems enable differential allocation of effort to various functions under different conditions, some of which vary in patterns that are predictable such as circadian, menstrual, seasonal, and life cycles. For many species, daytime functions such as seeking food and avoiding predators are achieved with sympathetic activity while night-time functions such as internal processing are achieved with parasympathetic activity. For organisms that maintain thermal homeostasis year-round, cooler temperature seasons may demand sympathetic bias to drive adaptive thermogenesis. Reproduction may necessitate autonomic shift to sympathetic bias during the luteal phase and pregnancy to modulate immune balance towards a more tolerant Th2 bias. Many diseases including infectious, cardiovascular, inflammatory, pulmonary, metabolic, fertility, oncologic, and neurologic conditions also show variation in prevalence over these cycles. The co-variation of autonomic balance and diseases over time intervals suggests that autonomic balance, by its direct effects as well as its indirect effects through modulation of T helper immune balance, plays an under-recognized role in diseases. The theory is extended to the co-variation of autonomic balance and diseases over the lifespan. Termination of organisms during senescence, achieved by emergence of autonomic imbalance and other systemic dysfunctions, is explored from a Darwinian perspective.

Adaptation, Physiological↗

PubMed2000

Simulation of cow-calf production systems in a range environment: II. Model evaluation.

Development of a general beef cattle simulation model was described in a companion paper. The objectives of this research were to demonstrate and evaluate the model's performance. Four experiments were conducted to demonstrate 1) life-cycle weight and body condition changes for different genotypes raised in a northern range environment; 2) responses in forage intake and weight to changes in forage quality, protein supplementation, and cow physiological state; 3) responses in reproduction, weight, body condition, and calf growth to differences in pre- and postpartum nutrition; and 4) differences in enterprise efficiency and profit for different genotypes and mating systems. Results indicated that the model performs acceptably for the types of situations for which it was designed and highlighted areas of animal science where more information is needed in order to better understand and manipulate beef cattle systems. Computer simulation models are useful tools to facilitate the integration of scientific concepts and to help scientists, teachers, and producers better understand the complex production systems that they study and manage. In addition to addressing enterprise-level problems that are beyond the scope of traditional experimentation, modeling and simulation help identify research needs and foster exchange among disciplines.

Animal Feed↗