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Results 251 - 300 of 1066
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Love O P - - 2008
Maternal glucocorticoids are known to affect offspring phenotype in numerous vertebrate taxa. In birds, the maternal transfer of corticosterone to eggs was recently proposed as a hormonal mechanism by which offspring phenotype is matched to the relative quality of the maternal environment. However, current hypotheses lack supporting information on both ...
Lebigre C - - 2007
In bird species with pair bonds, extra-pair matings could allow females to choose genetically superior males. This is not needed in lekking species because female choice is not constrained by pairing opportunities. However, polyandry has been reported in most lekking species studied so far. Using 12 microsatellite loci, we determined ...
Stölting Kai N - - 2007
Pregnancy has been traditionally defined as the period during which developing embryos are incubated in the body after egg-sperm union. Despite strong similarities between viviparity in mammals and other vertebrate groups, researchers have historically been reluctant to use the term pregnancy for non-mammals in recognition of the highly developed form ...
Swaab Dick F - - 2007
During the intrauterine period the human brain develops in the male direction via direct action of a boy's testosterone, and in the female direction through the absence of this hormone in a girl. During this time, gender identity (the feeling of being a man or a woman), sexual orientation, and ...
Nazarova L A - - 2007
We developed a method for synchronous registration of electrical activity of the myometrium in pregnant rabbit females and electrocardiograms of the female and fetus on a paper tape and on PC in the online mode using an original pickup for registration of intrauterine pressure in awaken animals in a natural ...
Shaw Donald - - 2007
In Siberian hamsters, juvenile somatic and reproductive development is influenced by the photoperiods experienced both during gestation and after birth. On the day of parturition, parents and young were transferred from either 16L (16 hr of light and 8 hr of darkness/day) or 10L to one of the three photoperiods ...
Wong C L - - 2007
The functional significance of male accessory sex glands (ASG) remains unclear. This study explored their importance in reproduction. In previous investigations, embryos sired by males with ASG either totally or partially removed had a shift in the cell cycle and delayed cleavage during preimplantation development, higher incidence of apoptosis, early ...
Lummaa Virpi - - 2007
In mammals, including humans, female fetuses that are exposed to testosterone from adjacent male fetuses in utero can have masculinized anatomy and behavior. However, the reproductive consequences of such prebirth sex-ratio effects for offspring and their implications for maternal fitness remain unexplored. Here we investigate the effects of being gestated ...
Puscheck Elizabeth E - - 2007
PURPOSE OF REVIEW: The present paper reviews the current literature on the impact of male factor on recurrent pregnancy loss. RECENT FINDINGS: Most clinicians focus their evaluation of recurrent pregnancy loss on the female, without much, if any, consideration of the other half of the couple - the male. Yet, ...
Roselli Charles E - - 2007
A sexually dimorphic nucleus that can be identified in adult sheep by its characteristic pattern of cytochrome P450 aromatase mRNA exists in the preoptic/anterior hypothalamic area and is called the ovine sexually dimorphic nucleus (oSDN). In other species, male-typical sexually dimorphic preoptic nuclei develop under the influence of gonadal testosterone ...
Kühl Aline - - 2007
In polygynous mammals, males generally benefit more from extra allocation of maternal resources than females. However, limitations to sex-specific allocation are usually ignored. We propose the 'allocation constraint' hypothesis, whereby maternal resource allocation is more likely to follow life-history predictions in single sex litters than in mixed sex litters, due ...
Jones Margaret E E - - 2007
Aromatase deficiency is rare in humans. Affected individuals cannot synthesize endogenous estrogens. Aromatase is the enzyme that catalyzes conversion of androgens into estrogens, and if aromatase is nonfunctional because of an inactivating mutation, estrogen synthesis cannot occur. If the fetus lacks aromatase activity, dehydroepiandrosterone sulfate produced by the fetal adrenal ...
Landon Jason - - 2007
Intrauterine growth restriction can lead to significant long-term health consequences such as metabolic and cardiovascular disorders, but less is known about its effects on choice and behavioral adaptation in later life. Virgin Wistar rats were time mated and randomly assigned to receive either ad-libitum access to chow or 30% of ...
Xie Youfu - - 2007
The female red Duroc pig has been found to be a promising model of hypertrophic scarring. The female Yorkshire pig has been demonstrated to heal in a very different manner, more resembling human normotrophic scarring. Given these observations, we studied microvessel density, an important aspect of wound healing, in human ...
Kamimura Y - - 2007
Male and female genitalia generally show a rapid evolutionary rate, which raises the problems related to homologization and the determination of the polarities of evolutionary changes. In earwigs (Dermaptera), multiple or branched female sperm-storage organs (spermathecae) have been reported for members of the Karschiellidae, Pygidicranidae, and Diplatyidae, collectively termed the ...
Thompson Roger N - - 2007
The vomeronasal organ (VNO) has evolved to link an animal's behavior to its environment in a highly species-specific fashion. In mice, it is thought to be the primary sensory system responsible for the detection of pheromones. Pheromones regulate a variety of responses including mate recognition in the context of selective ...
Saxena Arun Kumar - - 2007
A study was undertaken to determine the rate of population expansion of an ischnoceran Phthiraptera, Goniocotes gallinae (infesting the domestic fowl, Gallus gallus domesticus), on the basis of in vitro and in vivo studies. Data obtained from in vitro rearing were utilized to construct the life history of the louse. ...
Chaturvedi S - - 2007
A population-based cross-sectional inquiry was carried out in Delhi to assess the practice of fetal sex determination, sex-selective abortions and awareness about the related law. A total of 1514 respondents, selected through multistage cluster sampling from all across Delhi, were interviewed using a pretested, semistructured questionnaire. Legal awareness (73.6%) was ...
Di Renzo Gian Carlo - - 2007
In maternal fetal medicine, gender differences in outcome are often observed. This article reviews the fetal sex-dependent differences found in many aspects of pregnancy, from conception through birth. The MEDLINE, EMBASE, and Current Contents databases were searched, for the years 1985 to 2006, using the following Medical Subject Headings and ...
Hepner Absalom D - - 2007
BACKGROUND: The prevalence of mitral valve prolapse (MVP) has been reported to be 2.4% according to the Framingham Heart Study. However larger trials have found the prevalence of MVP to be less than 1.5%. We studied the prevalence of MVP using a large echocardiographic database. METHOD: We retrospectively analyzed 24,265 ...
Risch Thomas S - - 2007
We studied litter size variation in a population of Richardson's ground squirrels (Spermophilus richardsonii) in Alberta, Canada, from 1987 to 2004. Litter size at first emergence of juveniles from the natal burrow ranged from 1 to 14; the most common litter sizes, collectively accounting for 41.0% of 999 litters, were ...
Gerrard Edward R ER - - 2007
OBJECTIVE: To determine the effect of female partner age on pregnancy rates after vasectomy reversal. DESIGN: Retrospective review. SETTING: Two academic infertility practices. PATIENT(S): Men undergoing vasectomy reversal and their partners. INTERVENTION(S): Microsurgical vasectomy reversal. MAIN OUTCOME MEASURE(S): Patency and pregnancy rates. RESULT(S): Two hundred ninety-four patients met the inclusion ...
Rubolini Diego - - 2007
Maternal hormones in vertebrate eggs can mediate important forms of maternal effects. However, the function of hormone transfer to the eggs is still debated, especially because long-term fitness consequences have been little studied. We investigated the effect of prenatal exposure to physiologically elevated yolk testosterone (T) levels on reproduction of ...
Linde Forsberg Catharina - - 2007
BACKGROUND: Dystocia occurs more commonly in some breeds of dogs than others. The Boxer breed is one of the highrisk breeds for whelping problems. The aim of this study was to document some reproductive parameters and the frequency of dystocia in Boxers. METHODS: Two questionnaires were sent to the breeders ...
Buckley David - - 2007
The way in which novelties that lead to macroevolutionary events originate is a major question in evolutionary biology, and one that can be addressed using the fire salamander (Salamandra salamandra) as a model system. It is exceptional among amphibians in displaying intraspecific diversity of reproductive strategies. In S. salamandra, two ...
Féron Christophe - - 2007
In many rodent species males display paternal behaviour. The primary reported effect of this paternal care is to increase pup survival. In mammal females, pregnancy and lactation are energetically demanding, especially when they are concurrent in post-partum reproduction. To face this energy requirement, females generally lengthen the duration of their ...
Gilbert Jeffrey S - - 2007
Inadequate nutrition compromises fetal development and poses long-term health risks for the offspring, even without decreased birth weight. The present study sought to 1) establish the ontogeny of fetal renal glomerulus number (GN) in sheep and 2) evaluate the effects of 50% global nutrient restriction (NR) during early to midgestation ...
Lisboa Sabrina F S - - 2007
BACKGROUND/AIMS: Fluoxetine (FLX) has been widely prescribed for depression during pregnancy and/or lactation. Since serotonin is a neurotrophic factor, the use of FLX by mothers could disrupt brain development resulting in behavioral alterations in their progeny. This study evaluated the effects of developmental FLX exposure on anxiety, depression, aggressivity and ...
Covert S F - - 2007
We investigated the sexual reproductive mode of the two most important etiological agents of soybean sudden death syndrome, Fusarium tucumaniae and Fusarium virguliforme. F. tucumaniae sexual crosses often were highly fertile, making it possible to assign mating type and assess female fertility in 24 South American isolates. These crosses produced ...
Mukhopadhyay Arnab - - 2007
What is the relationship between reproduction and longevity? Evolutionary biology suggests that reproduction exacts a cost in somatic maintenance, a cost that reduces longevity. The frequent occurrence of this tradeoff between life span and fecundity, both due to experimental manipulations as well as natural variation, suggest that the mechanism might ...
Hayes UnJa L UL Department of Psychology and Center for Neuroendocrine Studies, University of Massachusetts, Tobin Hall, Amherst, MA 01003, USA. - - 2007
In prairie voles (Microtus ochrogaster), most virgin females are infanticidal. To determine the onset of maternal responsiveness, female prairie voles were tested for maternal behavior as virgins and at different times throughout pregnancy. Female voles that were infanticidal as virgins by and large remained infanticidal throughout pregnancy. In contrast, about ...
Xu Da-De - - 2007
We studied sexual dimorphism, female reproduction and egg incubation of the oriental leaf-toed gecko (Hemidactylus bowringii) from a population in southern China. The largest male and female in our sample were 60 and 57 mm snout-vent length (SVL), respectively. Males are the larger sex; sexual dimorphism in head size and ...
Miller Kimran E - - 2006
Callitrichid females are often described as energetically constrained. We examined the energy budgets of 10 female wild golden lion tamarins (GLTs, Leontopithecus rosalia) in an effort to understand how energy intake and expenditure might influence physical condition and therefore reproductive performance. We used focal animal sampling to record behavioral data ...
Costantini Ruth M - - 2007
Reproductive behavior of virtually all adult male rodents is dependent on concurrent availability of gonadal steroids. The ejaculatory reflex is incompatible with long-term absence of testicular steroids and typically disappears within 3 weeks after castration. Male Siberian hamsters are an exception to this rule; mating culminating in the ejaculatory reflex ...
Suraweera N - - 2006
Min mice provide a good model of human familial adenomatous polyposis. Recently, we have reported on two recombinant inbred lines (I and V) and the location of a modifier (Mom3) close to Apc, which altered polyp numbers in our mice possibly by modifying the frequency of wild-type (WT) allele loss ...
Stark Michael J - - 2006
OBJECTIVE: Peripheral microvascular function is altered in preeclampsia (PE). Recent studies suggest that maternal physiology varies with fetal sex. We wanted to examine if there were sex-specific differences in maternal peripheral microvascular function in normal pregnancy and pregnancy complicated by PE. METHODS: Peripheral microvascular responses were examined using the noninvasive ...
van Dunné F M - - 2006
Interleukin-10 (IL10) is assumed beneficial for a successful pregnancy; it may increase fertility and fecundity. Allele frequencies of IL10 polymorphisms at position -2849, -1082 and -592 were analyzed in association with a past history of fertility and fecundity in men and women of at least 85 years old. Fertility was ...
Gidlöf Sebastian - - 2007
CONTEXT: The mechanisms behind onset of labor and prolongation of pregnancy are not fully understood, but steroid hormones are thought to contribute. 17-Hydroxyprogesterone has been shown to prolong pregnancy in humans. Male fetuses have been reported to have longer gestation than females. OBJECTIVE: The objective of the study was to ...
Browne P - - 2006
Female spotted hyenas (Crocuta crocuta) have an erectile peniform clitoris and a pseudoscrotum but no external vagina, all established by day 35 of a 110-day gestation. Recent studies indicate that these events are androgen-independent, although androgen secretion by fetal ovaries and testis was hypothesized previously to induce phallic development in ...
Glickman Stephen E - - 2006
Female spotted hyenas (Crocuta crocuta) are the only female mammals that lack an external vaginal opening. Mating and birth take place through a urogenital canal that exits at the tip of a hypertrophied clitoris. This 'masculine' phenotype spurred a search for an alternate source of fetal androgens. Although androstenedione from ...
Young Andrew J - - 2006
In cooperative animal societies, dominant females typically show higher breeding success than subordinates, and are commonly believed to control the extent of reproductive sharing. However, studies of social insect societies reveal that subordinates too can interfere with the breeding attempts of others, with important implications for the distribution of fitness ...
Cammack K M - - 2006
The damaging effects of heat stress on male fertility are evident in developing spermatozoa expressed in ejaculates 18-28 days post-stress in mice. Our objectives were to: (1) assess genetic variation in fertility of heat-stressed male mice and (2) determine response to selection for fertility after heat stress in male mice. ...
Waterland Robert A - - 2006
Transient environmental exposures during mammalian development can permanently alter gene expression and metabolism by influencing the establishment of epigenetic gene regulatory mechanisms. The genomic characteristics that confer such epigenetic plasticity upon specific loci, however, have not been characterized. Methyl donor supplementation of female mice before and during pregnancy permanently increases ...
Brown Lawrence M - - 2006
BACKGROUND: Pharmacist salary and wage surveys have been conducted at the state and national level for more than 20 years; however, it is not known to what extent, if any, wage disparities due to gender still exist. OBJECTIVES: The overall objective of this study was to determine if wage disparities ...
Boseret Géraldine - - 2006
The contribution of social factors to seasonal plasticity in singing behavior and forebrain nuclei controlling song, and their interplay with gonadal steroid hormones are still poorly understood. In many songbird species, testosterone (T) enhances singing behavior but elevated plasma T concentrations are not absolutely required for singing to occur. Singing ...
Khan Christin B - - 2006
The goal of this research was to determine when harbor seal pup vocalizations become sufficiently distinctive to allow individual recognition. A total of 4593 calls were analyzed from 15 captive pups. Nineteen were harsh, broadband, staccato calls used in an aggressive context. The rest were tonal "mother attraction calls," having ...
Dickinson Hayley - - 2007
We investigated the effects of maternal glucocorticoid exposure in the spiny mouse, a precocial species with a relatively long gestation, few offspring, and in which nephrogenesis is complete before birth. We hypothesized that exposure of the fetus to glucocorticoids before the formation of glomeruli would result in adult hypertensive offspring ...
Weatherhead Patrick James - - 2006
Variation in intrauterine exposure to hormones associated with variation in the sex of litter mates has well-established and far-reaching effects on sexual development in some mammals. Research on this phenomenon in reptiles is scant, but suggests that lizards may follow the mammalian model whereas snakes may be affected differently. We ...
Wood S L - - 2006
Our objective was to examine whether mouse lines divergently selected for response to fescue toxicosis differed in the impact of increasing reproductive intensity on growth, final weight or first and second parity reproduction. Resistant (R) and susceptible (S) females were never mated (NR), mated only once (low reproduction, LR), mated ...
Anway Matthew D - - 2006
The current study was designed to examine the actions of a model endocrine disruptor on embryonic testis development and male fertility. Pregnant rats (F0) that received a transient embryonic exposure to an environmental endocrine disruptor, vinclozolin, had male offspring (F1) with reduced spermatogenic capacity. The reduced spermatogenetic capacity observed in ...
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