bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of cortisol in preparing the fetus for birth
Authors: Liggins GC
Published: October 2005

The glucocorticoids, cortisol and corticosterone, have a unique function in the fetus in inducing a wide range of enzymes before birth that have little or no function during fetal life but on which survival after birth is dependent. The loss of the placenta at birth deprives the fetus of a source of oxygen, glucose and heat (among many other things) for which alternatives must be available immediately if survival is to be assured. In anticipation of these needs several organs undergo maturational changes in late pregnancy aimed at meeting these requirements. The lungs mature structurally and functionally, becoming distensible and capable of coping with high surface tension when air enters the alveoli with the first breath. In the liver, glycogen accumulates and gluconeogenesis is initiated to meet the demands for glucose until feeding begins. There is an increase in the production of tri-iodothyronine and catecholamines in preparation for the sharp increase in metabolic rate and thermogenesis associated with breathing and the cold environment. All these dramatic maturational events are regulated by cortisol as are numerous others in most organ systems that contribute to neonatal well-being but on which survival is less dependent. Pharmacological manipulation of these systems before birth has made a substantial contribution to improving human health.
Low molecular weight components in bovine semen diffusate and their effects on motility of bull sperm
Authors: al-Somai N , Vishwanath R , Shannon P , Molan PC
Published: October 2005

Dialysis of diluted semen before cryopreservation is beneficial to sperm survival. This is due to removal of low molecular weight components from seminal plasma that are damaging to sperm. The apparent molecular weights (M(r)) of these components range between 1000 and 12,000 as estimated by gel permeation chromatography and electrophoresis. The detrimental effect on sperm motility is greatest with the components of M(r) between 5000 and 12,000 and with those of M(r) < 1500. Their effect on sperm motility was dependent on concentration. The small molecular weight components were derived from the high molecular weight components of seminal plasma through disaggregation under prescribed conditions.
Survival of ram spermatozoa at high dilution: protective effect of simple constituents of culture media as compared with seminal plasma
Authors: Ashworth PJ , Harrison RA , Miller NG , Plummer JM , Watson PF
Published: October 2005

During incubation of ram spermatozoa at 1 x 10(7) cells mL-1 or less in a simple HEPES-buffered saline medium, high levels of cell death were detected using propidium iodide as a probe of viability (membrane integrity): some 70% of the cells died during 3 h incubation at 37 degrees C. Because the conditions of incubation were similar to those encountered during manipulations for in vitro fertilization, this phenomenon was investigated further. If ram spermatozoa were diluted in an equivalent sucrose-based medium, or if the saline medium was supplemented with 10% seminal plasma, survival was greatly improved (only 5-15% died during a 3-h incubation at 37 degrees C); the protective effect of seminal plasma resided in a 5-10 kDa fraction. Sperm death in the basal saline medium was strongly dependent on cell concentration below 5 x 10(7) spermatozoa mL-1 whereas little effect of concentration was seen in the sucrose medium or in the presence of seminal plasma. The presence of Ca2+ (2 mM), EGTA (1 mM) or mercaptoethanol (1 mM) enhanced sperm survival in saline medium, but no effect was gained by replacing NaCl with KCl, and neither BSA nor fetal calf serum were beneficial. However, when a combination of pyruvate (1 mM), lactate (21.7 mM), Mg2+ (0.4 mM), phosphate (0.3 mM) and Ca2+ (2 mM) was included in the saline medium (to render it similar to Tyrode's medium), cell survival was greatly improved (12% died during the 3-h incubation).(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of culture in vitro and organ culture on the dry mass of preimplantation mouse embryos
Authors: Turner K , Rogers AW , Lenton EA
Published: October 2005

The dry mass of mouse embryos cultured in vitro in medium alone or in an organ culture system were measured by means of the Vickers M86 scanning microinterferometer. The data were compared with previous data on the dry mass of preimplantation embryos in vivo. The metabolism of embryos cultured in vitro differs from that of fresh embryos. In cultured embryos, dry mass decreases throughout the 2-cell stage whereas the dry mass is increasing at this stage in vivo. Embryos in an organ culture system regain a dry mass profile, similar to that observed in vivo at the late cleavage stage. These results support the view that conditions for embryo metabolism are suboptimal in vitro and that, although the oviduct may confer some advantage on developing embryos in vitro, it is unable fully to support the pattern of metabolism, as assessed by dry mass, observed in vivo.
Effect of post-ovulation nutritional status in ewes on early conceptus survival and growth in vivo and luteotrophic protein secretion in vitro
Authors: Wallace JM , Aitken RP , Cheyne MA
Published: October 2005

Overfeeding during early pregnancy in ewes compromises pregnancy establishment and/or embryo survival. To determine whether high feed intakes after ovulation alter the secretory dialogue between the conceptus and the endometrium, 24 embryos (8-16-cell) from ewes fed maintenance rations were synchronously transferred in singleton on Day 3 of the cycle (oestrus, Day 0) into the uterus of ewes receiving a high or low plane of nutrition from Day 0 (n = 12 ewes per group). Embryo survival and conceptus growth were assessed on Day 16. At this time, pregnancy was maintained in 11 of 12 recipient ewes per group and conceptus mass was not influenced by nutritional plane (637 +/- 48 v. 583 +/- 72 mg for high and low groups respectively). Conceptus and endometrial tissues were cultured separately for a further 24 h in vitro in the presence of [3H]leucine. There was no quantitative difference between nutritional treatments in the incorporation of radiolabel into proteins synthesized and secreted by the conceptus or endometrium. Secretion of ovine trophoblast protein-1 was also similar in both groups. Peripheral progesterone concentrations were significantly (P < 0.05) lower throughout the luteal phase in recipient ewes on high v. low intakes after ovulation. This effect was independent of ovulation rate which was 3.1 +/- 0.40 and 2.6 +/- 0.25 corpora lutea for high and low groups respectively. A high plane of nutrition after ovulation did not influence embryo survival and development in vivo or luteotrophic protein secretion in vitro despite a reduction in peripheral progesterone concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of active immunization against the amino-terminal peptide (alpha N) of the alpha 43 kDa subunit of inhibin (alpha 43) on fertility of ewes
Authors: Findlay JK , Russell DL , Doughton B , Tsonis CG , Borchers C , Forage RG
Published: October 2005

Immunization against the amino-terminal peptide (alpha N) of the alpha 43 subunit of inhibin was shown previously to reduce fertility in ewes. The aim of this study was to examine the effects of active immunization of ewes against alpha N on egg recovery and fertilization rates. Ewes were immunized against alpha N immunogen, and were given 800 I.U. of pregnant mare's serum gonadotrophin at the end of treatment with intravaginal progesterone to synchronize the oestrous cycles. Control ewes received adjuvant only. The ewes were run with fertile rams, and 4 days after withdrawal of the progesterone device the oviducts were flushed to recover eggs and luteal structures on the ovaries were recorded. Eggs were recovered from 17/19 (90%) control ewes compared with 4/16 treated ewes (25%) (P < 0.01), and the egg recovery rates were 76% (45/59) and 17% (7/42) respectively (P < 0.001). The mean number of corpora lutea (CL) per ewe were similar (3.1 +/- 1.4 v. 2.6 +/- 1.0) but several CL in the treated ewes did not appear to have ruptured, and 2 treated ewes had cystic follicles and no CL. There were no apparent differences in either the fertilization rates or the stages of development of fertilized eggs between treated and control ewes. Antibody binding levels in follicular fluid were approximately half those found in peripheral plasma. It is concluded that immunization of ewes against alpha N leads to lowered fertility by suppressing ovulation, implicating alpha N in the normal ovulatory process.
Identification of sperm antigen targets for immunocontraception: B-cell epitope analysis of Sp17
Authors: O'Rand MG , Widgren EE
Published: October 2005

The selection of immunological targets present on gametes is an important first step in the successful production of animal or human vaccines for immunocontraception. One strategy with regard to sperm antigens is to select antigens with physiological roles in gamete interaction, obtain the mRNA sequence for such an antigen, and then determine which region or domain of the molecule is available to the immune system when spermatozoa are presented to the female reproductive system. To illustrate this strategy, we have used the rabbit sperm antigen Sp17 (RSA-3), which has been cloned and sequenced. The peptide pin-block method of Chiron Mimotopes, Australia, has been used to analyse the 146 amino acids of Sp17 with various homologous and heterologous antisera. This study demonstrates that such an analysis can lead to the identification of a B-cell epitope with strong immunocontraceptive potential.
Contraceptive vaccine assessment based on a murine ZP3 mini-autoantigen
Authors: Tung KS , Lou YH , Luo AM , Ang J
Published: October 2005

A summary is presented of published and some unpublished observations from studies on the immunological response of mice to a 13-mer peptide of the murine ovarian zona pellucida glycoprotein ZP3. The findings have the following implications for the design of immunocontraceptive vaccines. To be reversible, a ZP3 vaccine must not contain pathogenic T cell epitopes of ZP3, but contraception without autoimmune oophoritis may be feasible. The immune response to the ZP3 mini-autoantigen is highly variable among inbred mouse strains, suggesting that a single oophoritogenic peptide would not achieve irreversible contraception in an outbred population. The discovery of antigen mimicry at the level of T cell peptide has thrown doubt on the validity of current strategy in detecting relevant self-antigens that might cross react with vaccine immunogens and on the feasibility of fully predicting the cross-reactive autoimmunogenic potential of a peptide or polypeptide vaccine antigen. Autoantibodies directed against epitopes outside the ZP3 mini-autoantigen, produced by immunization with the pure T cell epitope, react with high affinity, with native zona pellucida, and may be useful in identifying B cell epitopes in ZP3.
The common mucosal immune system: from basic principles to enteric vaccines with relevance for the female reproductive tract
Authors: McGhee JR , Xu-Amano J , Miller CJ , Jackson RJ , Fujihashi K , Staats HF , Kiyono H
Published: October 2005

The realization that induction of immune responses at mucosal surfaces may prevent colonization, invasion or dissemination of pathogenic microorganisms has spurred intensive efforts to develop vaccines which elicit effective mucosal immunity. In this paper, recent results are discussed for mice given cholera toxin as both an immunogen and as an adjuvant for inducing both humoral and gastrointestinal mucosal immune responses. Oral administration of cholera toxin alone or with a co-administered protein vaccine tetanus toxoid induces a strong T helper type 2 (TH2) cell response in both Peyer's patches and spleen. Both serum IgG and secretory IgA antibodies specific for cholera toxin or for the co-administered protein tetanus toxoid were induced. When administered parentally, however, no mucosal antibody responses were evident and a mixed TH1- and TH2-type CD4+ T cell response was noted in the spleen. Various vectors are being employed in an effort not only to induce mucosal immune responses but also to direct the response to a TH1-type response, thought to promote strong cell-mediated immune responses, or to a TH2-type response for maximum B cell antibody responses. The ability to manipulate the TH cell responses may provide a more rational approach for the design of vaccines. Although lymphoid tissues of the female reproductive tract differ from that of the gut, many of the strategies and evolving principles may be directly applicable to the development of vaccines designed to prevent sexually transmitted diseases.
Enhancement of mucosal IgA responses by interleukins 5 and 6 encoded in recombinant vaccine vectors
Authors: Ramsay AJ , Leong KH , Boyle D , Ruby J , Ramshaw IA
Published: October 2005

The expression of the genes for murine interleukin-5 (IL-5) or IL-6 in recombinant vaccinia virus vectors markedly increased IgA reactivity to co-expressed heterologous antigen in the lungs of mice inoculated intranasally with the viruses. These elevated local IgA responses reached a peak four times higher than those elicited by control viruses 14 days after infection and these peak levels were maintained for at least four weeks. Elevated IgA responses, reaching a peak 3-4 weeks after immunization, were also observed in the lungs of mice inoculated with IL-6 expressed by another vector, fowlpox virus. The results indicate that these factors enhance the development of mucosal IgA reactivity in vivo and suggest that their expression in mucosal vaccine vectors may stimulate local immune responses. The approach described in this study may be useful in stimulating mucosal immunity to a wide range of vector-encoded antigens, not only for vaccination against disease but also for immunocontraception by the co-expression of antigens involved in reproduction.
Disease and fertility control in wildlife and feral animal populations: options for vaccine delivery using vectors
Authors: Boyle DB
Published: October 2005

A wide variety of vertebrates have been introduced into Australia during the 200 years of European settlement. Many have become pests causing significant environmental damage and having the potential to act as reservoirs of infectious diseases. Control of vertebrate pest species by fertility control is attractive on animal welfare grounds. Should exotic animal diseases become established in any of these feral animal populations vaccination would be an essential element in the control or eradication of disease. The only experience to date with vaccination of wildlife or feral animals has been the successful control of rabies in foxes in Europe by means of a live, attenuated rabies vaccine and a vaccinia-rabies recombinant vaccine. The feasibility of vaccination for disease control or fertility control in other vertebrate pests will depend on the development and evaluation of several vaccine vector strategies. The choice of vector, based on live viruses or bacteria, naked DNA coding for vaccine antigen or virus-like particles encapsidating genetic material coding for vaccine antigen, will depend on optimization of vector delivery strategies and immunogenicity of the vaccine antigen. Past experience from the vaccination of foxes against rabies suggests that rates of uptake of the vaccine bait and immunogenicity of the vaccine will be crucial factors in determining the success of other vaccines controlling disease or fertility.
A comparison of sperm and embryo transport in the female reproductive tract of marsupial and eutherian mammals
Authors: Taggart DA
Published: October 2005

A review on current knowledge of sperm and embryo transport in the female reproductive tract of marsupials. Some of the unique features of gamete structure-function and female genital tract morphology will be described and compared with data available on eutherian mammals.
X-chromosome replication patterns in adult, newborn and prenatal opossums
Authors: Robinson ES , Samollow PB , VandeBerg JL , Johnston PG
Published: October 2005

Somatic cells from the opossums Monodelphis domestica and Didelphis virginiana were labelled with 5-bromodeoxyuridine (BrdU), treated with colchicine, stained with acridine orange and examined using fluorescence microscopy. BrdU-incorporated metaphase spreads from females of M. domestica at developmental stages from late bilaminar blastocysts to adults showed replication asynchrony of the two (acrocentric) X chromosomes. The long arm of one X chromosome was the latest replicating region in the entire chromosome complement and is presumed to represent transcriptional inactivation and X dosage compensation. The minute short arm of the same X, which contains a nucleolar organizer region, was earlier replicating and synchronous with the short arm of its homologue and is thus assumed to escape inactivation. BrdU-incorporated spreads from cells of fetuses, neonates and adults of D. virginiana also showed a late replicating (submetacentric) X chromosome. The pattern was different from that of M. domestica because of the different morphology and the presence of large blocks of constitutive heterochromatin in both homologues. The timing and pattern of replication of the single X in males of both species resembled the earlier replicating X in females. The array of molecular techniques now available offers the best means for investigating X-chromosome replication and activity states of X-linked genes in the earliest stages of marsupial embryogenesis.
Site-specific transgene insertion: an approach
Authors: Wigley P , Becker C , Beltrame J , Blake T , Crocker L , Harrison S , Lyons I , McKenzie Z , Tearle R , Crawford R , et al
Published: October 2005

Methods to improve the production of transgenic animals are being developed. Conventional transgenesis, involving microinjection of DNA into fertilized eggs, has a number of limitations. These result from the inability to control both the site of transgene insertion and the number of gene copies inserted. The approach described seeks to overcome these problems and to allow single copy insertion of transgenes into a defined site in animal genomes. The method involves the use of embryonic stem cells, gene targeting and the FLP recombinase system.
Virus-vectored immunocontraception for control of wild rabbits: identification of target antigens and construction of recombinant viruses
Authors: Holland MK , Jackson RJ
Published: October 2005

The need to control animal populations arises in many situations in the world from a variety of motives. Present control strategies are almost universally based on lethal procedures. Increasingly, there is dissatisfaction with such approaches from many different perspectives. In response to these concerns, the concept of controlling populations of pest species through control of their fertility has been mooted. Successful examples of this approach exist in cases of small, discrete pest populations but application of this to a widely distributed species over a broad geographical area has not yet been achieved. In this article, we report on a new approach to fertility control, virus-vectored immunocontraception, and discuss its applicability to control of wild rabbit populations. Particular emphasis is placed on the strategy for selection of a target molecule capable of inducing an immunocontraceptive response and on how the gene encoding such a molecule might be engineered into the myxoma virus for distribution into the population. The fact that the procedures for antigen identification and the viral engineering methods used are, to varying extents, generic means that the broad principles of this approach are applicable in other species.
Transgenic livestock as genetic models of human disease
Authors: Petters RM
Published: October 2005

Genetic models of human disease can lead to new insights concerning disease aetiology or suggest novel therapeutic interventions. Livestock species, especially pigs, cows, sheep and horses, are often good animal models of human disease. However, genetic models in livestock species have included only the study of spontaneous mutations. Production of transgenic livestock is now possible but owing to a low efficiency of production, it is very expensive and its application limited. Anticipated application of improved technologies such as embryonic stem cells and homologous recombination will allow for increased sophistication of experimental design and wider use of genetically modified livestock. In all cases, the appropriate species for a genetic model of human disease should be the species which best models the physiology of the organ or system under consideration. In the future, livestock will play an increasingly more important role in biomedical research through the application of genetic engineering methodologies.
Challenges and progress in the production of transgenic cattle
Authors: Eyestone WH
Published: October 2005

The production of transgenic cattle presents a number of unique challenges not encountered in other species. First, the survival of microinjected zygotes is low; only 15% in vivo-derived develop into morulae and blastocysts and, of these, only about 18% yield live calves. Second, transgene integration frequency is relatively low, around 3%. Thus, more than 1000 zygotes must be injected to produce a single transgenic calf. Obtaining sufficient zygotes from donor cattle to sustain a transgenic cattle programme is logistically and financially prohibitive, since the average superovulated donor yields only about four microinjectable zygotes per collection attempt. In vitro oocyte maturation and fertilization techniques may be used to alleviate this problem, although initially the developmental potential of in vitro-derived microinjected zygotes is lower than their in vivo-produced counterparts (8% v. 15%, respectively, yield morulae and blastocysts). Since only 3-5% of calves born from microinjected zygotes produced in either fashion yield transgenics, at least 20-30 pregnancies must be carried to term for every transgenic calf born. These conditions require that large herds of donor and recipient cattle be maintained. Recipient requirements could be reduced if transgene integration frequency could be increased, but improvements in the near future are unlikely since the mechanism of integration after pronuclear microinjection is poorly understood. Alternatively, embryos could be screened for integrated transgenes before transfer; however, efforts in this area have been complicated by high frequencies of false positive results. Although yet to be developed, bovine embryonic stem cells would alleviate many of these problems and permit a wider range of genetic manipulations.
Association of glycerylphosphorylcholine with human sperm and effect of capacitation on their metabolism
Authors: Mitra J , Chowdhury M
Published: October 2005

The presence and localization of glycerylphosphorylcholine (GPC) on the surface of human sperm, as well as the metabolism of its breakdown product L-glycerol 3 phosphate (G3P), were investigated. GPC was found to be associated with sperm after penetrating cervical mucus and was present after repeated washing of the sperm. GPC was partially released by treatment with 0.4 M NaCl in 0.01 M sodium phosphate buffer (pH 7.4) and localized to the head region after sperm fractionation. G3P did not increase O2 uptake of uncapacitated human sperm. However, under aerobic conditions, lactate accumulated when exogenous G3P or uterine GPC diesterase was added to sperm in suspension. The uptake of O2 by washed capacitated sperm pre-incubated with 1 unit of rat uterine GPC diesterase for 30 min was significant. This effect was inhibited by 2 microM oligomycin indicating that oxidative phosphorylation had occurred. The present study indicates that GPC may play a role in the metabolism of human sperm after capacitation.
Induction of cyclooxygenase and prostaglandin E2 production by the bovine pre-embryo
Authors: Gurevich M , Shemesh M
Published: October 2005

A study was conducted to determine the induction of cyclooxygenase production in the cleaved and non-cleaved oocyte and to measure the secretion of prostaglandin E2 (PGE2), PGF2 alpha and tumour necrosis factor-alpha (TNF alpha) in the conditioned medium of non-mature oocytes (denuded), mature oocytes (oocyte-cumulus complex), cleaved oocytes, and non-cleaved oocytes (mature oocytes incubated in the absence of sperm). Cyclooxygenase was readily detectable in 48-h cleaved oocytes whereas the signal for the enzyme in the non-cleaved oocytes was weak or undetectable. Cyclooxygenase expression in the cleaved oocytes was transient and enzyme concentrations at the early morula stage (72 h) were low. Measurable amounts of both PGE2 and TNF alpha were secreted during the first 24 h of maturation and 6 h after fertilization, whereas PGF2 alpha was undetectable at these times. There was a dramatic enhancement in PGE2, PGF2 alpha and TNF alpha secretion 48 h after fertilization. At 72 h after fertilization, PGE2 concentrations were much lower and PGF2 alpha was again undetectable which corresponded to a low concentration of cyclooxygenase. In contrast, high TNF alpha activity continued to be detected even 72 h after fertilization. It is possible that the induction of the production of cyclooxygenase and the secretion of PGs and TNF alpha by fertilized oocytes at specific times after fertilization plays a role in the regulation of embryonic development, maternal immunological recognition of pregnancy, and the maintenance of a suitable hormonal environment for embryonic viability.
Spermatogenic cells and stages of the seminiferous epithelial cycle in the Indian gerbil field rat, Tatera indica
Authors: Bilaspuri GS , Kaur R
Published: October 2005

Four types of spermatogonia (A0, A, In, B) are distinguished in T. indica. Four generations of A type, a single generation of intermediate (In) and two generations of B type spermatogonia are identified. Seven divisions of spermatogonia have been observed, in Stages 1b, 2b, 3b, 4b, 5, 6 and 7 respectively. Spermatocytes have been observed in prophase, metaphase, anaphase and telophase; in terms of size and morphology, the phases of prophase could be further divided. Pre-leptotene and leptotene appear in Stage 8 and Stage 1 respectively. Round spermatids become asymmetrical in Stage 1b. For the first time in rodents, Stages 1, 2, 3, 4 and 8 have been subdivided. The percentage frequencies of Stages 1-8 are 12.93, 10.69, 17.54, 10.33, 3.76, 11.20, 7.88 and 25.67 respectively. Although the morphology of the spermatogenic cells and associations of these cell types are basically similar to those in albino rats, T. indica markedly differs from all other rodents studied in having two generations of B spermatogonia and subdivisions of Stages 1, 2, 3, 4 and 8; in addition, the relative frequencies of the stages distinctly differ from those recorded in previous studies of rats. Hence, the durations of different cell types in T. indica may differ markedly from those in other rodents.
The effects of bromocriptine on lactation and subsequent reproduction in grey kangaroos, Macropus fuliginosus and Macropus giganteus
Authors: Hinds LA , Tyndale-Biscoe CH
Published: October 2005

Both species of grey kangaroo were tested to determine whether a single exposure to bromocriptine in mid winter will terminate lactation, and whether females that cease to lactate will return to oestrus immediately and give birth early, or at the next summer breeding season. In Experiment 1, 11 lactating western grey kangaroos (Macropus fuliginosus) received injections either of saline (n = 2) or of bromocriptine at dose rates of 0.2, 1.0 or 5.0 mg kg-1 bodyweight (n = 3 per dose). Pouch young of females treated with the highest dose of bromocriptine showed either retarded growth or no growth, but they subsequently survived. In Experiment 2, lactating western (n = 12) and eastern grey kangaroos (M. giganteus) (n = 14) received a single intramuscular injection of saline or approximately 2 mg kg-1 or 4 mg kg-1 Parlodel LA (a long-acting form of bromocriptine) and their young were weighed. Within 3 weeks, the young of all 19 females treated with Parlodel LA had lost weight and 17 had died, whereas only one young, which had not lost weight, was lost from the seven control females. The western grey females did not give birth until the normal summer breeding season but the eastern grey females gave birth 2-4 months early. It is concluded that bromocriptine has potential for the humane control of grey kangaroo populations.
Variation in reproductive parameters in the captive male koala (Phascolarctos cinereus)
Authors: Cleva GM , Stone GM , Dickens RK
Published: October 2005

Plasma androgen concentration was measured in six mature male koalas over 23 months. During this time, four animals were housed isolated from females. Androgen concentration showed a seasonal change, with a nadir about the middle of the year, and began to increase sometime before the start of the breeding season. The concentration was greater when males were housed with females, even when the females were not yet cycling themselves. Changes in androgen concentration were not associated with changes in testicular volume. When plasma extracts were examined following separation by high pressure liquid chromatography, the major circulating androgen was testosterone with only trace amounts of 5 alpha-dihydrotestosterone present. Plasma androgen fluctuated during the day suggesting some form of diurnal rhythm of secretion. Two further animals were fitted with vascular access ports to allow more frequent blood collection and samples were taken every second day for two months, a period that included a major portion of the breeding season. Androgen concentration fluctuated widely from 0 nmol L-1 to 20 nmol L-1 over successive sampling and indicating an episodic pattern of secretion. Plasma cortisol concentration was measured in all animals in these studies to monitor stress and remained low except when animals were undergoing surgery, were being moved to different enclosures or were exhibiting reproductive behaviours. Overall, there was no significant correlation between the concentration of androgen and cortisol in plasma (n = 215). This contrasted with a group of wild-bled animals (n = 4) where there was a highly significant negative correlation.
Testicular and epididymal sperm content in grazing Cashmere bucks: seasonal variation and prediction from measurements in vivo
Authors: Walkden-Brown SW , Restall BJ , Taylor WA
Published: October 2005

Each month, for 15 months, the testes and epididymides were recovered from five Australian cashmere bucks selected at random from a group of mature bucks (initial n = 116) at pasture (location 29 degrees S, 153 degrees E). The extent of seasonal change in testicular and epididymal sperm reserves was determined and indirect methods for predicting these reserves were developed. Paired testicular weight exhibited clear seasonal variation from 137 g in August to 269 g in February. The total elongated spermatid content of the testes, determined by homogenization, showed a very similar seasonal pattern, ranging from 13.8 x 10(9) in September to 36.2 x 10(9) in March. Seasonal changes of similar timing were observed for paired epididymal weight and sperm content. Although changes in total testicular spermatid content were largely the result of change in testicular weight (R2 = 0.72, P < 0.001), the elongated spermatid content of testicular parenchyma (mean, 127 x 10(6) g-1) exhibited significant seasonal variation with elevated values between February and June, suggestive of an increase in the efficiency of spermatogenesis. Daily sperm production, calculated by means of a spermatogenic time divisor for sheep, ranged from 2.76 x 10(9) in September to 7.23 x 10(9) in February. Scrotal circumference, scrotal volume and testicular length x diameter2 were identified as accurate predictors of testicular weight (R2 > or = 0.87) and sperm content (R2 > or = 0.70). The results demonstrate that: (a) cashmere bucks exhibit considerable seasonal variation in spermatogenesis associated primarily with changes in testicular mass but also with changes in the efficiency of spermatogenesis; and (b) indirect measures of testicular size are good predictors of testicular elongated sperm content. When the correct spermatogenic time divisor for goats is determined, such indirect measures may be used to predict daily sperm production.
Immunocytochemical localization and changes in endometrial progestin receptor protein during the porcine oestrous cycle and early pregnancy
Authors: Geisert RD , Pratt TN , Bazer FW , Mayes JS , Watson GH
Published: October 2005

Changes of progesterone receptor (PR) protein and cellular localization in the endometrium were evaluated during the oestrous cycle and early pregnancy of the gilt. During the oestrous cycle, the concentration of total PR protein within the endometrium was highest on Days 0-5 and decreased on Day 10. The endometrial concentration of PR reached a nadir on Day 12 and this level was maintained throughout the remainder of the oestrous cycle (Day 18). In pregnant gilts, the concentration of endometrial PR protein from Day 10 to Day 18 was similar to that in cyclic gilts. Western blot analysis with antiserum specific for the A and B isoforms of PR indicated that porcine endometrium expresses both isoforms of PR. Immunostaining was detectable for both the A and B isoforms of PR from Day 0 to Day 12 of the oestrous cycle. However, no staining was observed on Day 15 and Day 18 of the oestrous cycle or pregnancy Immunocytochemical localization of PR in the endometrium of cyclic gilts and pregnant gilts indicated that there was intense staining for PR in surface epithelium and glandular epithelium during oestrus (Day 0) and on Day 5. However, the staining was less intense on Day 7 and Day 10 of the oestrous cycle and no epithelial staining was observed after Day 12. PRs were present in the stroma and myometrium throughout the oestrous cycle and early pregnancy. The presence of conceptuses during pregnancy did not affect the loss of PR from the uterine epithelium after Day 10 of gestation. Down-regulation of epithelial PR might be one factor involved in the timing of luteolysis during the oestrous cycle as well as conceptus growth and placentation during early pregnancy.
Comparisons between peripheral progesterone concentrations in cyclic and pregnant Landrace x large White and Meishan gilts
Authors: Ashworth CJ , Ross AW , Haley CS
Published: October 2005

Progesterone concentrations were determined in blood samples collected twice daily (at 0900 and 1700 hours) from the day of oestrus (Day 0) until Days 15-24 in ten Landrace x Large White gilts (four cyclic and six pregnant gilts) and eight Meishan gilts (four cyclic and four pregnant gilts). Progesterone concentrations during the early luteal phase tended to be higher in pregnant Meishan gilts than in pregnant Landrace x Large White gilts. Furthermore, when differences in ovulation rate and peak progesterone concentrations were accounted for, maximum progesterone concentrations occurred earlier in Meishan gilts than in Landrace x Large White gilts (P < 0.01); this difference was particularly marked when pregnant animals of the two breeds were compared. In non-mated animals, analyses of the timing and magnitude of progesterone concentrations observed towards the end of the oestrous cycle revealed that the decrease in progesterone concentrations occurred earlier (P < 0.05) in Meishan gilts. Such breed differences in the peripheral progesterone profile may be associated with reduced prenatal mortality, a characteristic of Meishan females.
Intrauterine and peripheral steroid concentrations and conceptus development in Meishan and Large White hybrid gilts
Authors: Hunter MG , Faillace LS , Picton HM
Published: October 2005

Six Meishan and five Large White hybrid gilts were naturally mated to boars of the same breed during their tenth or third oestrous cycle respectively. Maternal serum progesterone and total oestrone were monitored throughout the pregnancy period. On Day 30 of gestation, all gilts were slaughtered and ovulation rate, embryonic survival, conceptus development and intrauterine steroidogenesis were evaluated. The results of the study confirm previous reports that Meishan pigs have a higher number of live conceptuses (P < 0.03), a higher rate of embryonic survival (92.1% v. 78.6% for Large White hybrids) and a higher ovulation rate (P < 0.02) than Large White hybrid gilts. Embryos from Large White hybrid gilts were heavier (P < 0.001) than Meishan embryos and placental lengths (P < 0.001) and weights (P < 0.001) were greater. The volume of allantoic fluid per conceptus was greater (P < 0.03) in Large White hybrid gilts. The oestradiol concentration in the allantoic fluid was greater in Large White hybrid gilts (P < 0.002), but the progesterone concentration in allantoic fluid did not differ (P > 0.15) between the breeds. More oestradiol was synthesized in vitro on a wet weight basis from placental tissue in Large White hybrid gilts than in Meishan gilts (P < 0.001); however, a positive linear relationship existed in both breeds between oestradiol synthesis and placental length (P < 0.005). Progesterone concentrations in maternal serum tended to be higher overall (P < 0.1) in Meishan gilts than in Large White hybrid gilts throughout the 30-day period of study and were significantly higher (P < 0.02) from Day 13 to Day 30.(ABSTRACT TRUNCATED AT 250 WORDS)
Cellular composition of primary cultures of human granulosa-lutein cells and the effect of cytokines on cell proliferation
Authors: Wang LJ , Brannstrom M , Pascoe V , Norman RJ
Published: October 2005

The cellular composition of cells collected from the follicular fluid obtained during the IVF procedure and cultured in vitro was examined, as well as the effects of two cytokines, interleukin-2 (IL-2) and tumour necrosis factor-alpha (TNF alpha), on the proliferation of individual cell types. After 48 h in culture, most of the cells were granulosa-lutein cells exhibiting positive staining against 3-beta-hydroxysteroid dehydrogenase (3 beta-HSD). About one-third of the total cell population stained positive with monoclonal antibodies against specific antigen sites on lymphohaemopoietic cells, including B-lymphocytes, T-lymphocytes, natural killer cells, monocytes and macrophages. During this 48-h period, IL-2 and TNF alpha significantly (P < 0.05) increased the proportion of leukocyte common antigen (LCA)-positive cells and monocytes. At the end of 144 h in culture, although LCA-positive cells and monocytes were still present, there were fewer. The main targets for the proliferative effects of IL-2 and TNF alpha in this culture system during the first 48 h are leukocytes rather than steroid-producing cells. Thus, any observed effects from the addition of cytokines in this system may be due to indirect effects of cytokine-activated leukocytes on granulosa-lutein cells.
Interactions between large and small luteal cells collected during the mid- or late-luteal stages of the bovine oestrous cycle
Authors: Del Vecchio RP , Thibodeaux JK , Saatman R , Hansel W
Published: October 2005

The effects of contact between large and small bovine luteal cells together with those of luteinizing hormone (LH) or arachidonic acid (AA) on progesterone production during the oestrous cycle were investigated. Corpora lutea were collected during the mid-luteal stage (Days 10-12; n = 4) and late-luteal stage (Days 17-18; n = 4) of the oestrous cycle. Large and small luteal cells were dispersed and separated and then incubated together or separately. Mid-luteal stage cells were treated with LH (0 or 5 ng) whereas late-luteal stage cells were treated with LH (0 or 5 ng) or AA (0 or 10 microM). Culture medium was collected and replaced 1, 3 and 6 h after starting treatments. Progesterone production decreased (P < 0.0001) with increased incubation time irrespective of cell arrangement, the stage of the oestrous cycle or treatment. During the 18 h before treatment, cells in the contact arrangement produced more progesterone (P < 0.003) than cells without contact in both mid- and late-luteal stages of the oestrous cycle; progesterone production within cell arrangements between prospective treatment groups was similar. After initiating treatments, mid-luteal stage cells in the control group without contact produced more progesterone (P < 0.01) than cells with contact. Mid-luteal stage cells treated with LH produced more (P < 0.0001) than control cells; progesterone production between cell arrangements within the LH treatment group was similar. In the late-luteal stage cells, both LH and AA increased (P < 0.01) progesterone production by comparison with control cells; LH and AA treatment groups produced similar results.(ABSTRACT TRUNCATED AT 250 WORDS)
Platelet-activating factor-antagonists reduce implantation in mice at low doses only
Authors: O'Neill C
Published: October 2005

The effects of a number of platelet-activating factor (PAF)-antagonists on embryo implantation were investigated. Mice were treated from Day 1 to Day 4 of pregnancy with three defined PAF-antagonists: SRI 63 441, BN 52021, and WEB 2086. Necroscopies were performed on Day 8 and the number of implantation sites, the implantation rate (number of implanted embryos compared with the number of corpora lutea) and the proportion of animals pregnant were determined. Each agent caused a reduction in the number of implantation sites at relatively low doses. The dose that had a maximum contragestational effect was 40 micrograms, 10 micrograms and 10 micrograms (per 30 g bodyweight per day) for SRI 63 441, WEB 2086 and BN 52021 respectively. This contragestational effect was completely lost at twice (SRI 63 441), five times (WEB 2086) and ten times (BN 52021) the most effective dose. Treatment with WEB 2086 on the day of implantation (Day 4) by intraperitoneal injection or instillation into the uterus only did not significantly reduce the implantation rate and neither did treatment after implantation (Days 5-8). The results show that the pharmacology of PAF-antagonists in early pregnancy is not simple. An understanding of the actions of these agents in early pregnancy will require a detailed knowledge of their pharmacokinetics, pharmacodynamics and targets of action in early pregnancy.
Inhibition of glyceraldehyde 3-phosphate dehydrogenase in boar spermatozoa by bromohydroxypropanone
Authors: Porter LM , Jones AR
Published: October 2005

In the presence of 3-bromo-1-hydroxypropanone (BOP), cauda epididymal sperm obtained from mature boars produced a carbonyl compound which is assumed to be (S)-3-bromolactaldehyde. Glyceraldehyde 3-phosphate dehydrogenase was rapidly inhibited which resulted in the accumulation of dihydroxyacetone phosphate and fructose-1,6-bisphosphate, and no accumulation of lactate when fructose was the substrate. The energy charge potential of the cells declined in the presence of BOP when either fructose or glycerol were substrates. It is suggested that BOP is transformed into (S)-3-bromolactaldehyde, which is the actual inhibitor of glyceraldehyde 3-phosphate dehydrogenase, thus demonstrating BOP to be the first brominated chemical to have an anti-glycolytic action on mature sperm in vitro.
Large equine blastocysts are damaged by vitrification procedures
Authors: Hochi S , Fujimoto T , Oguri N
Published: October 2005

Viability following vitrification of equine blastocysts with different sizes was investigated in vitro. Twenty-four blastocysts were classified into three groups according to their diameters (< 200 microns, 200-300 microns and > 300 microns; n = 8 each). The solution used for vitrification was defined as EFS and contained 40% ethylene glycol, 18% Ficoll and 0.3 M sucrose in modified-phosphate-buffered saline (m-PBS). During pretreatment with 20% ethylene glycol in m-PBS for 20 min, the larger blastocysts responded to the osmotic pressure caused by 20% ethylene glycol more slowly than the smaller blastocysts. Single blastocysts were loaded into the EFS in 0.25-mL straws, left to stand for 1 min and vitrified in nitrogen vapour. After thawing for 20 s in water (20 degrees C), a fractured zona pellucida or capsule was seen in: 1 of 8 blastocysts < 200 microns in diameter; 1 of 8 blastocysts 200-300 microns in diameter; and 2 of 8 blastocysts > 300 microns in diameter. When the blastocysts were cultured for 48 h in TCM199 supplemented with 10% fetal bovine serum at 37 degrees C in 5% CO2 in air, 7 of 8 (88%) blastocysts < 200 microns in diameter and 6 of 8 (75%) blastocysts 200-300 microns in diameter developed with re-expansion of the blastocoele. However, the developmental ability of blastocysts > 300 microns in diameter (2 of 8, 25%) was significantly lower than that of blastocysts < 200 microns in diameter (P < 0.05).
Relationship between testicular morphology and sperm production following ischaemia in the ram
Authors: Markey CM , Jequier AM , Meyer GT , Martin GB
Published: October 2005

Arteriosclerosis was induced in the internal spermatic artery of rams to determine if this condition is implicated in the aetiology of testicular pathology which causes male infertility. Data were collected on sperm concentration and motility for 56 days following surgery to provide an index of testicular function. Testes were then weighed and a testicular biopsy score count was performed on histological sections to assess spermatogenic potential of seminiferous tubules. Vascular disturbance caused focal damage of the seminiferous epithelium, similar to that seen among infertile men, and a reduction in ejaculate volume, sperm concentration and sperm motility. Sperm concentration decreased following ischaemia yet was maintained to some degree by a germ-cell depleted spermatogenic epithelium. Normal testicular morphology was maintained above a testis weight of about 120 g (for an individual testis), but below this threshold spermatogenesis was severely impaired. In conclusion, these data have provided information on the relationship between testicular morphology and function following ischaemia in the ram. Furthermore, the morphological changes induced in the testis were similar to those seen among infertile men and, by their focal nature, could explain the distinction between oligozoospermia and azoospermia in men exhibiting spermatogenic arrest.
Spermatids as male gametes
Authors: Ogura A , Yanagimachi R
Published: October 2005

Intracytoplasmic sperm injection (ICSI) is becoming increasingly popular in human infertility clinics as an efficient method for the treatment of male infertility. It is proposed that spermatids can be used as substitutes for spermatozoa if men are unable to produce sperm in their testes. At least in the hamster and mouse, the nuclei of round spermatids were capable of participating in syngamy when incorporated into homologous mature oocytes either by microsurgical ICSI or electrofusion. Normal mouse offspring were born after after electrofusion of oocytes with round spermatids. When culture in vitro of spermatogonia and spermatocytes is perfected, then spermatids, transforming spermatids and spermatozoa will all be able to be used as male gametes.