bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical intracytoplasmic sperm injection (ICSI) results from Royal North Shore Hospital
Authors: Catt JW , Ryan JP , Pike IL , O'Neill C , Saunders DM
Published: October 2005

The technique of intracytoplasmic sperm injection (ICSI) was first introduced to the Royal North Shore Hospital in April 1993 as part of a controlled study of 100 patient cycles in which sibling oocytes were inseminated by either subzonal insemination (SUZI) or ICSI. This trial showed direct sperm injection to be superior in terms of fertilization. In that study, 58 embryo transfers of 101 ICSI-derived embryos resulted in 10 pregnancies. No miscarriages have occurred and a total of 10 fetal hearts (9.8% per embryo transferred) were detected on ultrasound. There have been 10 deliveries of 10 babies. Since the beginning of 1994, intracytoplasmic injection has been used exclusively for patients requiring micromanipulation to achieve fertilization. There have been 200 patient cycles with 1650 oocytes collected (8.8 oocytes per cycle). Of these oocytes, 1548 were mature (94%) and were subjected to ICSI, and normal fertilization occurred in 874 (56%) of the injected oocytes. The number of oocytes which cleaved and were suitable for fresh transfer or cryopreservation was 818 (94%). There have been 153 fresh embryo transfers of 326 embryos. Twenty-six pregnancies (17% per embryo transfer) have resulted, 22 of which proceeded to ultrasound examination in which 23 fetal hearts were detected (7% per embryo transferred). Three miscarriages have occurred, leaving 19 ongoing pregnancies. There have been 127 cryopreservation procedures involving 492 embryos. To date, there have been 47 embryo thaw cycles, and 93 of the 115 (81%) thawed embryos survived and were transferred. These 47 embryo transfers resulted in 10 pregnancies (21% per embryo transfer), one of which one has miscarried.(ABSTRACT TRUNCATED AT 250 WORDS)
Intracytoplasmic sperm injection (ICSI): the Brussels experience
Authors: Tournaye H , Liu J , Nagy Z , Joris H , Wisanto A , Bonduelle M , Van der Elst J , Staessen C , Smitz J , Silber S , et al
Published: October 2005

The present report covers the results of a 26-month period in which 1275 consecutive treatment cycles by intracytoplasmic sperm injection (ICSI) were performed in 919 couples. These couples were afflicted with male factor infertility and had had at least one previous failed conventional in vitro fertilization (IVF) treatment cycle. In other couples, the husband had semen parameters incompatible with conventional IVF or suffered from excretory azoospermia which required microsurgical epididymal sperm aspiration or testicular sperm retrieval. Overall, the 2 pronuclear (PN) fertilization rate was 47.7% per retrieved oocyte-cumulus complex and 66.4% per successfully injected metaphase II oocyte. Embryo transfer was performed in 90.8% of started cycles and 362 clinical pregnancies were recorded, giving a clinical pregnancy rate of 28.4% per started cycle or 31.3% per transfer. In addition, updated results on the outcome of pregnancies after microassisted fertilization are presented. As of 30 August 1994, 416 children have been born. Although 16 major congenital malformations have been observed (3.9%), there appears to be no reason for serious concern as regards the occurrence of major congenital anomalies after ICSI.
Interferon, the oxytocin receptor and the maternal recognition of pregnancy in ruminants and non-ruminants: a comparative approach
Authors: Flint AP
Published: October 2005

Ruminant and non-ruminant members of the Artiodactyla appear to use different mechanisms for the maternal recognition of pregnancy. In ruminants, the trophoblast of the developing blastocyst produces a characteristic Type I interferon of the interferon-tau family; this acts by blocking endometrial synthesis of the oxytocin receptor. A similar mechanism applies to domestic ruminants (sheep, cow, goat) and deer. In roe deer, which have embryonic diapause and are monoestrus, there is no requirement for a pre-implantation blastocyst signal to ensure maternal recognition of pregnancy. This paper compares the mechanisms leading to the maternal recognition of pregnancy in ruminants with that suggested to occur in a non-ruminant (the domestic pig).
Placental control of fetal growth
Authors: Robinson J , Chidzanja S , Kind K , Lok F , Owens P , Owens J
Published: October 2005

The placenta exerts its effects on the growth of the fetus from the beginning of pregnancy via metabolic and endocrine mechanisms. To achieve this, the placenta exchanges a wide array of nutrients, endocrine signals, cytokines and growth factors with the mother and the fetus. These exchanges modulate or programme fetal growth and development. This review concentrates on the function and structure of the placenta in humans and in animals, and the effects of experimental perturbation of placental size and function on fetal growth. The consequences for fetal growth of varying the abundance of peptides or, by deleting genes, insulin-like growth factors or cytokines, are also described. Maternal nutritional and hormonal state from as early as the first few days after fertilization, can influence the growth rate of the placenta and the fetus and also the length of gestation. Influences on placental development and their consequences will clearly have an impact on the placental control of fetal growth. Variations in the maternal environment and consequent perturbation of the metabolic and endocrine environment of the placenta and fetus are implicated as being responsible for the associations between prenatal growth of the placenta and its fetus and the subsequent risk of adult disease. The next challenge will be to determine the dominant influences at each stage of fetal and placental growth.
Endocrine regulation of fetal growth
Authors: Fowden AL
Published: October 2005

Hormones have an important role in the control of fetal growth. They act on both tissue accretion and differentiation and enable a precise and orderly pattern of growth to occur during late gestation. In part, their actions on growth may be mediated by other growth factors such as the insulin-like growth factors (IGFs). Insulin stimulates fetal growth by increasing the mitotic drive and nutrient availability for tissue accretion. It has little effect on tissue differentiation. In contrast, the main effects of cortisol in utero are on tissue differentiation and maturation. Cortisol appears to act directly on the cells to alter gene transcription or post-translational processing of the gene products. Cortisol may also initiate the transition from the fetal to the adult modes of growth regulation by inducing the switch from IGF-II to IGF-I gene expression in the fetal liver. Thyroxine affects both tissue accretion and differentiation in the fetus by a combination of metabolic and non-metabolic mechanisms. Pituitary growth hormone, on the other hand, appears to have little part in the control of fetal growth, unlike its role postnatally. Fetal hormones, therefore, promote growth and development in utero by altering both the metabolism and gene expression of the fetal tissues. These hormonal actions ensure that fetal growth rate is commensurate with the nutrient supply and that prepartum maturation occurs in preparation for extrauterine life.
Day-night changes in c-fos expression in the fetal sheep suprachiasmatic nucleus at late gestation
Authors: Constandil L , Parraguez VH , Torrealba F , Valenzuela G , Seron-Ferre M
Published: October 2005

The suprachiasmatic nucleus (SCN) is a circadian oscillator in mammals and shows day-night changes in metabolic activity. To investigate whether the fetal sheep SCN behaves as a circadian oscillator, day-night changes in c-fos expression, a marker of neuronal activity, were measured. Eight fetal sheep were sacrificed at 135 days gestation--four at day-time (1200 hours) and four at night-time (2400 hours). Fetal brains were fixed, removed and cut in 40-microns serial coronal sections. Alternate sections were incubated with anti-Fos antibody (1:500) and Fos expression was revealed with extra-avidin-peroxidase and 3,3'-diaminobenzidine or stained with cresyl violet. The number of Fos-immunoreactive (Fos-ir) neurons per mm2 in the rostral, intermediate and caudal regions of the fetal sheep SCN was counted. Fetuses sacrificed in the day-time showed a higher number of Fos-ir neurons per mm2 (mean +/- s.e.; 516.7 +/- 60.1) in the three regions of the SCN than fetuses sacrificed at night-time (140.5 +/- 21.8). In addition, at night-time Fos-ir neurons were mainly localized to the ventrolateral area of the SCN. These findings demonstrate day-night changes in molecular activity consistent with the presence of a circadian oscillator in the fetal sheep SCN.
Development of renal function in the fetus: a review
Authors: Lumbers ER
Published: October 2005

This review concentrated mainly on studies of intrauterine renal function carried out in chronically-catheterized fetal sheep. In sheep, as in primates, nephrogenesis is complete before birth. Studies in the rat and neonatal puppy provide insight into the functional development of the kidney, because these species are immature at birth and there is considerable postnatal renal development. Studies of the ovine fetus provide insight into the physiological role(s) of the kidneys during intrauterine life, albeit modified by changes related to maturation.
Prenatal development of somatosensory primary afferent connections in the sheep
Authors: Rees S , Nitsos I , Rawson J
Published: October 2005

A summary is presented of recently published studies on the structural and functional development of cutaneous and muscle receptors and the connections of their afferent fibres in fetal sheep (n = 26) aged between 67 and 143 days gestation (term, 146 days). In these studies it was shown that primary afferent fibres projected to, and made synaptic connections with, dorsal horn neurons in lumbosacral spinal cord by 56-61 days gestation. Sensory innervation of the skin occurred later by about 75 days gestation and, at this age, stimulation of the skin first activated cutaneous afferent fibres and evoked a discharge in dorsal root ganglion and dorsal horn neurons. Muscle stretch first activated muscle spindles and evoked a discharge in dorsal root ganglion cells by about 75 days. Prior to this (by about 67 days) primary afferent fibres had begun to innervate motoneuron pools in the spinal cord, and motor nerves had begun to innervate muscle fibres. Both muscle spindle and cutaneous innervation were relatively simple at mid gestation indicating that the structure of sensory receptors need not be complex in order to generate a response. Neural pathways necessary for reflex activity involving muscle spindles are therefore present and functional by mid gestation as are cutaneous pathways projecting from the skin to the spinal cord.
Cerebral blood flow is increased throughout 12 h of hypoxaemia in the mid-gestation ovine fetus
Authors: McCrabb GJ , Harding R
Published: October 2005

The changes in regional cerebral blood flow (CBF) in response to prolonged hypoxaemia were measured using coloured microspheres in the 0.6-gestation ovine fetus (n = 5). Fetal hypoxaemia was induced for 12 h by reducing maternal uterine blood flow with an adjustable clamp. CBF (mL min-1 100 g-1) was increased (P < 0.05) from control values (38.7 +/- 3.5) to 105.6 +/- 5.6 at 6 h of hypoxaemia, and to 121.9 +/- 23.1 at 12 h of hypoxaemia. One hour after fetal hypoxaemia had ceased, CBF (54.0 +/- 3.3) had decreased (P < 0.05) towards control values indicating incomplete cardiovascular recovery. Cerebral vascular resistance at 6 h and 12 h of hypoxaemia was lower (P < 0.05) than control values, and returned to control values 1 h after fetal hypoxaemia had ceased. Cerebral oxygen delivery at 6 h and 12 h of hypoxaemia was not significantly different from control values, but was higher (P < 0.05) 1 h after hypoxaemia had ceased. It is concluded that CBF is sufficiently increased during prolonged hypoxaemia in the mid-gestation fetus to maintain cerebral oxygen delivery.
Chronic stress--the key to parturition?
Authors: McMillen IC , Phillips ID , Ross JT , Robinson JS , Owens JA
Published: October 2005

It is clear that the timing of parturition is dependent on a cascade of endocrine signals from an intact fetal hypothalamo-pituitary-adrenal axis. What is not known, however is the nature or source of the central neural stimulation which results in the stimulation of adrenocorticotrophic hormone (ACTH) synthesis and secretion in late gestation. The changes which occur in the synthesis and posttranslational processing of the ACTH precursor, proopiomelanocortin (POMC), in the fetal anterior pituitary before birth and the consequence of these changes for expression of the corticosteroidogenic enzymes in the fetal adrenal are described in this review. Evidence for the functional heterogeneity of corticotrophic cell types in the fetal sheep pituitary and the proposal that there is a maturational change in the populations of corticotrophic cells in late gestation are discussed. Finally, the development of cortisol negative feedback in the late gestation fetal hypothalamo-pituitary axis and the relevance of chronic stress to the timing of parturition are also discussed.
A cloning strategy for G-protein-coupled hormone receptors: the ovine beta 1-adrenergic receptor
Authors: Padbury JF , Tseng YT , Waschek JA
Published: October 2005

Regulation of beta 1-adrenergic receptors is unusual in developing animals. For example, glucocorticoid-and thyroid hormone-responsiveness for several genes is seen in animals treated during fetal life but beta 1-responsiveness is not seen until after birth. In order to investigate this at the transcriptional level, the ovine beta 1 receptor gene was cloned from a sheep genomic library. An approach using high-stringency screening with cDNA probes and oligonucleotides from regions of human and rat genes conserved but unique to the beta 1 receptor but not to other seven transmembrane, G-protein-coupled receptors. Over 800,000 clones were screened from which 40-50 positive clones were identified by each of the probes. There was, however, only a single clone which was recognized by each of the probes. A 5-kb insert was subcloned and shown to contain sequences which hybridized to each of the probes. Using the restriction map of the rat beta 1 receptor, a 1.0-kb Pst1 internal fragment was further subcloned for sequence identification. Confirmation of this fragment as the ovine beta 1 receptor was based on homology of the beta 1 receptor from other species and tissue distribution of mRNA. Nucleotide sequence homology was 93% with the human beta 1 receptor and 84% with rat. Amino acid sequence homology was > 75% and approached 100% in the transmembrane regions. The approach described represents a practical approach to cloning and identification of hormone receptors from the highly homologous members of the seven-transmembrane, G-protein-coupled receptors.
Fetal metabolic responses to hypoxia
Authors: Hooper SB
Published: October 2005

It has been known for may years that hypoxaemia in the fetus induces a number of biophysical, cardiovascular, endocrine and metabolic responses by the fetus, some of which are not sustained if the period of hypoxaemia is extended. For instance, fetal breathing and body movements and the circulating concentrations of many of the stress-related hormones return to control levels during prolonged periods of hypoxaemia. In particular, circulating fetal blood glucose concentrations gradually return to control levels, after an initial increase. The initial increase is primarily due to a catecholamine-mediated increase in glucose production from glycogen stores leading to a marked reduction in glycogen content. During prolonged periods of hypoxaemia, however, the decrease in fetal blood glucose concentrations is principally due to a decrease in the activity of the major enzymes responsible for glycogenolysis and not to a total depletion of glycogen stores. It is suggested that the decrease in enzyme activity could be due to a prostaglandin E2-mediated antagonism of catecholamine-activated glycogenolysis. In contrast, fetal blood lactate concentrations increase to a plateau after 4-5 h of hypoxaemia and remain at this elevated level for the duration of the hypoxaemia. Circulating lactate concentrations do not increase further, despite production by hypoxic tissues remaining high, due to an increase in lactate clearance by the placenta; under normal conditions the placenta releases lactate into the fetal circulation. It is considered that many of these changes are important adaptive responses which allow the fetus to survive in a sub-optimal intrauterine environment.
Nutrition and fetal growth
Authors: Harding JE , Johnston BM
Published: October 2005

Nutrient supply to the fetus is a key factor in the regulation of fetal growth. However, the direct supply of nutrients to provide building blocks for tissue growth is likely to be only a minor component of this regulation. The indirect effects of nutrition on fetal endocrine and metabolic status, and on the interaction between the fetus, placenta and mother all of which must be coordinated to allow fetal growth are also important. Maternal undernutrition may alter the growth of the fetus and its different component tissues in a way which cannot be explained solely on the basis of reduced substrate supply during the rapid growth phase of the tissues involved. Adaptation to altered substrate supply, during both undernutrition and refeeding, involves sequential changes in the metabolic and endocrine interactions between the fetus and the placenta. In addition, undernutrition has long-term consequences for the fetus. There is evidence for nutritional programming of fetal endocrine and cardiovascular systems before birth. Nutritional effects may also persist over more than one generation. The effects of nutrition on fetal growth are far more complex than simply those of substrate deprivation.
Cardiovascular responses to graded degrees of hypoxaemia in the llama fetus
Authors: Llanos AJ , Riquelme RA , Moraga FA , Cabello G , Parer JT
Published: October 2005

The fetal llama exposed to an intense degree of hypoxaemia did not increase cerebral blood flow, but showed a marked peripheral vasoconstriction. The same cardiovascular response is observed in fetal sheep submitted to a extremely severe hypoxaemia, when the initial compensatory vasodilatory mechanisms in brain and heart fail. To investigate whether the fetal llama responses to acute hypoxaemia are adaptive, or whether they are the result of a breakdown of mechanisms of blood flow redistribution that favours the central nervous system, we studied seven fetal llamas (0.6-0.7 of gestation) chronically-catheterized during 1 h of graded and progressive hypoxaemia. Fetal ascending aorta blood gases and fetal cardiac output and its distribution (radiolabelled-microspheres) were measured after 60 min of normoxaemia (B) and at the end of 20 min (H20), 40 min (H40) and 60 min (H60) of hypoxaemia. Data were analysed by ANOVA and Newman-Keuls tests. Each treatment resulted in a lower (P < 0.05) percentage of haemoglobin saturation than hypoxaemia; H40 was lower than H20, and H60 was lower than H20 and H40. No statistical difference was observed among treatments for cardiac output or cerebral blood flow. These results demonstrate that fetal cardiac output and brain blood flow are maintained at all degrees of hypoxaemia, indicating that these cardiovascular responses are an adaptive response in the llama fetus, rather than an index of cardiorespiratory decompensation.
A retrospective study of increased plasma progestagen concentrations in compromised neonatal foals
Authors: Rossdale PD , Ousey JC , McGladdery AJ , Prandi S , Holdstock N , Grainger L , Houghton E
Published: October 2005

Plasma progestagen concentrations were measured daily by radioimmunoassay (RIA) in 35 sick foals for the duration of their illness. The foals were divided into three groups on the basis of time to stand after birth. Foals were given intensive care treatment according to the severity of their illness. Plasma and urine concentrations of pregnenolone (P5) and pregnenediol (P5 beta beta) were measured by gas chromatography--mass spectrometry; plasma cortisol concentrations were measured by RIA and the foals' renal and respiratory status were assessed by creatinine clearance ratios and arterial oxygen concentrations respectively. Five patterns of plasma progestagen concentrations were identified; in general, values increased when the foal's clinical condition deteriorated and decreased as the foal improved. Median progestagen concentrations decreased over the first three days post partum in Group 1 foals but remained elevated in foals from Groups 2 and 3. Similar changes were observed in plasma P5 and P5 beta beta concentrations. Plasma cortisol concentrations were highest in foals from Groups 2 and 3 (P < 0.01) compared with foals from Group 1. Regardless of foal group, mean cortisol concentrations were highest (P < 0.001) in those foals treated with adrenocorticotrophic hormone compared with those treated with dexamethasone or with neither drug. There was no relationship (r2 = 0.21) between plasma cortisol and progestagen concentrations. Results from renal clearance, steroid conjugation and respiratory status suggest that these factors did not play a significant role in elevating progestagen concentrations in sick foals. It is hypothesized that there may be a relationship between adrenal stimulation and an enzyme block resulting in overproduction of P5 and P5 beta beta in the sick neonatal foal.
Free radicals, lipid peroxidation and sperm function
Authors: Aitken RJ
Published: October 2005

The cellular generation of reactive oxygen species was first observed in mammalian spermatozoa in the late 1940s. The field then remained dormant for 30 years until Thaddeus Mann and Roy Jones published a series of landmark papers in the 1970s in which the importance of lipid peroxidation as a mechanism for damaging mammalian spermatozoa was first intimated. The subsequent demonstration that human spermatozoa produce reactive oxygen species and are susceptible to peroxidative damage has triggered intense interest in the role of oxidative stress in the aetiology of male infertility. Moreover, data have recently been obtained to indicate that, although excessive exposure to reactive oxygen species may be harmful to spermatozoa, in physiological amounts these molecules are of importance in the control of normal sperm function. This review considers the dualistic role of reactive oxygen species and sets out the current understanding of the importance of oxidative processes in both the physiology and the pathology of the human spermatozoon.

Extra keywords: human spermatozoa, reactive oxygen species.
Spermatology for understanding, managing and conserving rare species
Authors: Wildt D , Pukazhenthi B , Brown J , Monfort S , Howard J , Roth T
Published: October 2005

Most conventional spermatology research involves common mammalian species including livestock, laboratory animals and humans. Yet, there are more than 4500 mammalian species inhabiting the planet for which little is known about basic reproductive biology, including sperm characteristics and function. This information is important, not just as adjunct knowledge, but because the majority of these species are threatened with extinction, largely due to human-induced pressures. The field of conservation is changing rapidly, and global cooperation is emerging among a variety of wildlife enthusiasts, ranging from management authorities of nature reserves to curators of rare zoological collections. Conservation progress depends on systematic, multidisciplinary research first to answer basic questions, with new data then applied to endangered species management plans. The reproductive physiologist is a crucial component of this scheme. Reproduction is the essence of species survival, and enormous effort needs to be directed at these 'untraditional' research species, subspecies and populations. Spermatology research combined with simultaneous efforts in endocrinology, embryology and cryopreservation (among others) can lead to the successful application of assisted reproduction. Examples from this laboratory include an array of wild felid species and a rare cervid and mustelid. Obstacles to success are formidable, including unique species-specificities, diminished genetic diversity and a general lack of resources. Nonetheless, the field offers tremendous opportunities for generating unique knowledge of comparative interest and with conservation utility.
Micro-assisted fertilization
Authors: Payne D
Published: October 2005

In couples who undergo routine in vitro fertilization (IVF), 17% experience significant problems with fertilization and many others are unable to have routine IVF because the quality of their semen is too poor. Often, the only options previously available to these couples were to use sperm donated by fertile men or to remain childless. Micromanipulative assisted fertilization techniques have improved the treatment of severe male factor infertility significantly and this paper provides a brief overview of the recent methodologies. Initially, techniques such as zona drilling and partial zona dissection, in which a hole or slit is placed in the zona pellucida, demonstrated that fertilization and pregnancies could be achieved with semen of very poor quality, but successes were sporadic. Later, subzonal injection of spermatozoa provided more consistent results with many units reporting pregnancies; however, relatively low rates of fertilization (14-34%) and high rates of polyspermy remained unresolved problems. The latest technique, the injection of a single spermatozoon into the oocyte cytoplasm, although technically difficult in animal models, proved to be highly successful in the human, restoring fertilization rates to those seen in routine IVF (65%) and producing good pregnancy rates from transferred embryos. Intracytoplasmic sperm injection has become the method of choice in the treatment of severe male factor infertility and preliminary data suggest that there is no increase in congenital abnormality among babies born after the transfer of injected oocytes.
Derivation and reliability of kinematic measures of sperm motion
Authors: Davis RO , Siemers RJ
Published: October 2005

Studies of sperm movement are relevant in the diagnosis of sperm function and in investigations of cellular biology. Such studies have been traditionally performed by analysing the kinematics of the flagellum or the head. Analysis of the flagellum can provide insights into the cell biological mechanisms responsible for the control of movement. However, the mathematical correspondence between head kinematics and flagellum kinematics is not unique. Therefore, it is not possible to use head kinematics to obtain detailed insights into cell mechanisms or physiology. The accuracy and precision of kinematic measurements are limited by a number of technical and biological factors. Therefore, the interpretation of kinematic data is dependent on a thorough understanding of the assumptions and conditions underlying the analysis. Evaluation of the reliability of kinematic measurements has suffered because no absolute standard for measurement has existed. The development and application of a new standard based on images which were simulated using the equations of motion is described. Because the kinematics of these images are known prior to empirical measurement, the performance of different methods can be determined absolutely. Some kinematic measures are unreliable because they are inappropriate analogues for engineering concepts. The development and use of appropriate engineering measures for the frequency and amplitude of sperm motion is also described. Some types of sperm motion cannot be analysed using kinematic measures (e.g. hyperactivated movement). The concept of the fractal dimension as a more accurate measurement for such motions is introduced. It is concluded that kinematic measurements of sperm motion can provide valuable information about cell biological mechanisms (in the case of the flagellum) and about general membrane and axoneme function (in the case of the head) when the measurements are made under the appropriate conditions, when standard techniques are followed, and when the assumptions underlying the analysis are well understood.
Ionic control of sperm function
Authors: Fraser LR
Published: October 2005

Successful sperm function leads to fertilization. It is dependent on the extracellular environment, especially the array and concentration of various ions. Considerable evidence indicates that this is because of consequent effects on the intracellular ionic composition. Although both cations and anions undoubtedly play a role in a modulating sperm function, most of the evidence currently available concerns cations. Therefore, this review will concentrate on cations, focussing on Ca2+, Na+, K+ and H+. Their requirements for successful capacitation (mammalian sperm) and acrosomal exocytosis (both invertebrate and mammalian sperm) will be considered. In particular, the mechanisms which may control ion fluxes, leading to changes in the intracellular ionic composition and subsequently to changes in sperm functional potential, will be addressed.
Interactions between gametes leading to fertilization: the sperm's eye view
Authors: Storey BT
Published: October 2005

Sexual reproduction requires that the gamete carrying the male-derived haploid chromatin join with the gamete carrying the female-derived haploid chromatin during fertilization to produce the diploid zygote. To accomplish this feat, the sperm must not only meet the egg, it must recognize the egg and be recognized in turn by the egg, and in the end must enter and be engulfed by the egg. In this selective overview of gamete interactions that lead to fertilization, encounters of three kinds, followed by the finale of gamete fusion, are considered from the sperm's viewpoint, with particular emphasis on the mammalian species with the mouse as the principal model. The first encounter is with the zona pellucida of the egg, to whose surface the sperm must bind. Mouse sperm appear to have four binding sites for zona ligands. Three interact with sugar moieties of the oligosaccharide chains of the mouse zona glycoprotein ZP3; the fourth binds a peptide backbone arginine. Capacitation is not required for this encounter, but is obligate for the second encounter--induction of the acrosome reaction in the bound sperm. The acrosome reaction is an exocytotic process that makes available the enzymatic machinery needed for sperm penetration the zona which is the end point of a sequence of reactions directed by intracellular signalling systems. In mouse sperm, these systems are presumed to be activated by ligands on ZP3 binding to ligand-specific sperm receptors with consequent aggregation of receptors. No receptor has been identified with certainty, nor have candidates for putative ZP3 ligands been identified. Completion of the acrosome reaction allows the sperm to penetrate the zona and, bind to the egg plasma membrane, thereby completing the third encounter. In the mouse, a 94-kDa protein appears essential for this binding. In the guinea-pig, a sperm plasma membrane protein (formerly PH-30, now fertilin), is a strong candidate for the mediator of the fusion process by which the egg engulfs the sperm. Decondensation of the sperm chromatin reverses the remarkable packing of DNA organized by sperm protamines. Mitochondrial DNA is also engulfed by the egg; the question of whether this DNA makes a small finite, or null, contribution to cytosolic inheritance is still in debate. The puzzles attending these encounters are presented as reminders of the intricacy and fascination, as well as of the vital necessity, of gamete interaction.
Aspects of current and future inhibin research
Authors: Burger HG , Farnworth PG , Findlay JK , Gurusinghe CJ , Healy DL , Mamers P , Mason A , Robertson DM
Published: October 2005

Inhibin was first isolated in 1985. Major progress has been made in defining various aspects of its structure and physiology, using a heterologous radioimmunoassay. Current research is aimed at characterizing the nature of the circulating forms of inhibin and is examining whether there are sex-specific roles for inhibins A and B. It has been recognized that various forms of epithelial and stromal ovarian cancer produce members of the inhibin peptide family but the precise nature of these products is not yet clear. The recognition that the inhibin subunits together with follistatin are expressed locally within the pituitary has lead to an investigation of their possible roles in intrapituitary regulation. It is clear that these peptides also have intragonadal roles. Of particular current interest is the nature of the signals that control the specificity of cellular peptide production and that determine whether a particular cell produces inhibin or activin. The inhibins are members of a complex family with many potential roles in physiology and pathophysiology. The role of the inhibins in feedback control of follicle stimulating hormone in the male, particularly, remains unclear. New applications for inhibin and related peptides are likely to be developed.
Monotreme and marsupial reproduction
Authors: Renfree MB
Published: October 2005

Marsupials were regarded as curiosities by their early European discoverers, animals to be wondered at. Monotremes were even more surprising; the platypus was such an amalgam of characters that it was thought to be a hoax. They were recognized very early as mammals that could make a major contribution to our understanding of reproductive processes, and work on marsupials at the turn of the century was much in evidence. It is, however, only in the past two decades, and especially in the past few years that marsupial research has regained this position. There is no doubt that future research will strengthen this contribution, but we are faced with serious conservation questions that must be solved if we are to maintain these wonderful animals as a resource for future generations.
Inhibition of glycolysis in boar spermatozoa by alpha-chlorohydrin phosphate appears to be mediated by phosphatase activity
Authors: Jones AR , Porter LM
Published: October 2005

(R,S)-alpha-chlorohydrin-1-phosphate, previously shown to have no anti-glycolytic activity on mature boar sperm in vitro, is a substrate for acid and/or neutral phosphatase(s) that are associated with washed sperm. The high phosphatase activity hydrolyses the ester to alpha-chlorohydrin which undergoes oxidation to (S)-3-chlorolactaldehyde, a specific inhibitor of sperm glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase, thereby exhibiting an anti-glycolytic action.
X-Y chromosome dissociation in mice and rats exposed to increased testicular or environmental temperatures
Authors: van Zelst SJ , Zupp JL , Hayman DL , Setchell BP
Published: October 2005

Heating the testes, scrota and tails of mice and rats by immersion in a water bath at 42 degrees C for 20 min caused an increased percentage of X-Y univalents in meiotic preparations made after 6 and 12 days respectively. It was also confirmed that exposing mice of a cool-adapted strain to an environment at 33 degrees C for 5 days resulted in an increase in the percentage of X-Y and autosomal univalents in meiotic preparations made after a recovery period of 2 days. Mice of a strain adapted to living at 33 degrees C also showed a higher rate of X-Y dissociation than control cool-adapted mice, but a lower frequency of autosomal univalents than cool-adapted mice exposed to the hot environment. The testes of the heat-adapted mice were even more sensitive than the testes of cool-adapted mice to the effects of local heating, as judged by the fall in testis weight 21 days afterwards.
Chromosome condensation activity (CCA) in bisected C57BL/6JxCBA mouse oocytes
Authors: Fulka J , Ouhibi N , Fulka J , Kanka J , Moor RM
Published: October 2005

Chromosome condensation activity (CCA) has been analysed in C57BL/6Jx CBA mouse oocytes bisected (i) shortly after germinal vesicle breakdown (GVBD), (ii) in metaphase I (MI) and (iii) in metaphase II (MII) into two equal halves (nucleated, enucleated) which were thereafter fused to S- or G2-phase 4-cell-stage mouse blastomeres. In nucleated halves, premature chromosome condensation (PCC) in transplanted nuclei was always induced irrespective of the cell cycle stage of the blastomere, whereas in enucleated halves only G2 nuclei underwent PCC after transplantation. Premature chromosome condensation in S-phase nuclei was induced only in enucleated halves produced shortly after GVBD. Although S-phase nuclei transplanted to MI or MII enucleated halves remained intact, their capacity to synthesize DNA was invariably suppressed. When spindles were destroyed by preincubation of the oocytes in colcemid before bisection, both nucleated and enucleated halves produced at MI or MII induced PCC of both G2- or S-phase nuclei. These results demonstrate that chromosome condensation activity in mammalian oocytes is compartmentalized rather than uniformly distributed across the cell, and that the enucleation of mammalian oocytes before nuclear transplantation may, under some conditions, influence the levels of CCA and subsequent response of introduced nuclei to cytoplasmic factors.
Peripheral plasma progesterone concentrations in pregnant and non-pregnant greyheaded flying-foxes (Pteropus poliocephalus) and little red flying-foxes (P. scapulatus)
Authors: Towers PA , Martin L
Published: October 2005

Blood was collected from breeding-season and pregnant P. poliocephalus females shot in the wild and from captive pregnant and ovariectomized P. poliocephalus and P. scapulatus females. Peripheral plasma progesterone concentrations measured by radioimmunoassay were similar to those obtained by gas chromatography-mass spectroscopy: in intact non-pregnant P. poliocephalus females without corpora lutea (CLs) values ranged from 2 to 30 ng mL-1; after ovariectomy, they ranged from 1 to 85 ng mL-1. A significant source of progesterone in these bats may be the adrenal. In P. poliocephalus, peripheral plasma progesterone concentrations showed relatively little change over the breeding season or in early pregnancy when a CL formed, but increased from mid pregnancy to reach 200-800 ng mL-1 in late pregnancy. A mid-pregnancy ovary with CL contained 2.80 ng progesterone whereas the contralateral ovary contained 0.13 ng. Overall, CL size decreased during pregnancy and was negatively correlated with plasma progesterone concentrations. In late pregnancy, the main source of progesterone appears to be the placenta; plasma concentrations increase with placental growth and are significantly correlated with placental weight, and placentas contain 4-8 micrograms progesterone g-1. There was no evidence that progesterone concentrations fall before parturition. Limited observations indicated that peripheral progesterone concentrations follow similar patterns in P. scapulatus.
Development of the gonads in the triploid (ZZW and ZZZ) fowl, Gallus domesticus, and comparison with normal diploid males (ZZ) and females (ZW)
Authors: Lin M , Thorne MH , Martin IC , Sheldon BL , Jones RC
Published: October 2005

Gonadal development in fowls aged from 1 day to more than 4.5 years was studied in 63 ZZW and 16 ZZZ triploid crossbreds and compared with normal diploid males (ZZ) and females (ZW). In the ZZW fowl, the right gonad developed into a testis (although this occurred earlier in the ZZ genotype), and a structurally-abnormal excurrent duct system containing some malformed spermatids and spermatozoa was associated with the gonad of young adults. The left gonad was an ovotestes at hatching and no excurrent ducts were associated with it. The ovarian component was much less developed than that in the ZW genotype-it started to degenerate by 1 week of age, and most of the oocytes had disappeared by about 3 weeks of age. The seminiferous tubules developed in the medullary region, but only abnormal spermatozoa were produced. Leukocytes infiltrated both gonads at about 9 months of age and the seminiferous epithelium had degenerated in most fowls over 1 year old. In ZZZ fowl, gonadal and excurrent duct development was normal, but occurred earlier than in the ZZ genotype. However, meiosis and spermiogenesis were abnormal and malformed spermatozoa were produced. The heads of spermatozoa from the ducts deferens were about 1.4-times longer in the ZZZ genotype than in the ZZ genotype, indicating that the former may be producing some diploid spermatozoa.
Cyclic alterations in rhesus monkey endometrium by scanning electron microscopy
Authors: Bhartiya D , Bajpai VK
Published: October 2005

The present study was undertaken to correlate the surface topography of endometrium with altered concentrations of circulating steroids during different phases of the artificially-induced menstrual cycle. Scanning electron microscopy demonstrated that oestradiol during the oestrogenic phase induces an increase in the number of ciliated cells and the size of microvilli; by contrast, progesterone, in addition to inducing secretory activity in non-ciliated cells, had a negative effect on oestradiol-dependent morphological characteristics of ciliated cells, causing a reduction in cell number and deciliation, and inducing drooping of cilia during the progestogenic phase of the artificially-induced menstrual cycle. In addition, surface and glandular epithelial cells both actively participate in restoration of the endometrial surface during the menstrual phase, an event which parallels endometrial shedding.
Concentrations of corticotrophin-releasing hormone in the umbilical-cord blood of pregnancies complicated by pre-eclampsia
Authors: Goland RS , Tropper PJ , Warren WB , Stark RI , Jozak SM , Conwell IM
Published: October 2005

The effect of pre-eclampsia on concentrations of corticotrophin releasing hormone (CRH) in umbilical-cord blood of fetuses at delivery was studied in order to determine if fetal CRH is elevated in this disorder when compared with uncomplicated pregnancy. Placental CRH may be a regulator of fetal pituitary-adrenal function and we therefore also measured ACTH, cortisol and dehydroepiandrosterone sulfate (DHEAS) in the umbilical-cord blood. The mean umbilical-cord plasma CRH in the fetuses from pregnancies complicated by pre-eclampsia, 667 +/- 153 pg mL-1, was significantly higher than the plasma CRH in the fetuses from normotensive pregnancies, 185 +/- 22 pg mL-1 (P < 0.001). The mean fetal cortisol concentration was significantly higher in pre-eclampsia, than in the normotensive, pregnancies (pre-eclampsia, 13.5 +/- 1.8; normotensive, 7.6 +/- 1.3 micrograms dL-1; P < 0.001). Plasma DHEAS was 217 +/- 23 micrograms dL-1 in the umbilical-cord blood of the fetuses from pregnancies complicated by pre-eclampsia and 281 +/- 35 micrograms dL-1 in the normotensive pregnancies (P < 0.01). Placental CRH synthesis and release, in contrast to hypothalamic CRH, appears to be stimulated by glucocorticoids. In pregnancies complicated by uteroplacental insufficiency, as may occur in pre-eclampsia, placental CRH production may be enhanced by increased fetal glucocorticoids. In turn, placental CRH may modulate fetal pituitary-adrenal steroidogenesis to favour increased cortisol secretion. Thus, placental CRH may play an important role in the fetal response to a compromised intrauterine environment.
Endothelin stimulates ACTH secretion in the ovine fetus
Authors: Greer IA , Thomas GB , Brooks AN
Published: October 2005

The endothelins are a series of peptides with potent vasoconstrictor effects in vascular tissue; however, they may also have a role as neuroendocrine secretagogues because endothelin and endothelin receptors have been found in hypothalamic and pituitary tissues. Since activation of the fetal hypothalamo-pituitary-adrenal axis is crucial to the process of parturition, the aim of this study was to determine whether endothelin could activate the hypothalamo-pituitary-adrenal axis in the ovine fetus. Catheters were inserted into the carotid artery, jugular vein and lateral cerebral ventricle of six fetal lambs at 118-122 days' gestation. After a 5-day recovery period, endothelin-3 or placebo (saline) was infused intravenously (i.v.) or intracerebroventricularly (i.c.v.) over 30-60 min. The dose of endothelin-3 employed was 0.01 and 0.1 microgram min-1 i.c.v. and 0.1 and 1.0 microgram min-1 i.v. Arterial blood was taken from the fetus before, during and for 1 h after the infusion for measurement of ACTH and cortisol. Blood gas analysis was also performed. Intravenous endothelin-3 produced a dose-dependent increase in ACTH and cortisol concentrations in fetal plasma and was associated with transient fetal hypoxia and acidosis. pH correlated inversely with plasma ACTH (r = -0.701, P < 0.001) and cortisol (r = -0.308, P < 0.001) concentration. An increase in ACTH and cortisol concentrations in fetal plasma was also induced by endothelin-3 administered i.c.v. at 0.1 microgram min-1, and this was not associated with fetal acidosis These data suggest that endothelin administered i.v. will stimulate ACTH and cortisol release indirectly through vasoconstriction and acidosis; however, the response to i.c.v. endothelin administration suggests that it may also act as a central secretagogue for ACTH in the fetus and could therefore play a role in the process of parturition.
Recording and analysis of uterine activity in pregnant guinea-pigs
Authors: Schellenberg JC , Lacey P , Withy S
Published: October 2005

Guinea-pigs are of considerable interest for the study of the physiology of parturition in view of their lack of placental 17-alpha hydroxylase, a property which they share with Man and monkeys. To allow long-term analysis of uterine activity, a chronic guinea pig model was developed carrying a uterine electromyogram (EMG) electrode array, intrauterine and intraabdominal balloon catheters and vascular catheters. Operative procedures and the characteristics of the hardware and software are described and evaluated. Quantitative analysis of uterine activity relies on the quasi-integrated EMG signal which is highly correlated with the raw EMG signal. Under optimal conditions of intrauterine pressure recording, the area of the quasi-integrated EMG signal is highly correlated with the area of the intrauterine pressure increment. The preparation is stable for at least four weeks, measurements are reproducible, and biologically meaningful results are obtained from the recordings.