bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex reversing non-disjunction of the Y chromosome produces exceptionally low sex ratio (% males) and hermaphrodites in the progeny of male BALB/cBm mice: the roles of the maternal genotype and the Y chromosome
Authors: Whitten WK , Carter SC , Beamer WG
Published: October 2005

When females of 21 strains and hybrids were mated to BALB/cBm males to determine the role of the maternal genome in the sex reversing non-disjunction of the Y chromosome, (1) BALB/cBm and BALB/cBy and SJL/J females produced 39.5-41.5% males and 2.4-2.8% hermaphrodites; (2) SWR/J, A/HeJ, DBA/2J and C3HeB/FeJ produced 44.8-49.1% males and 0.2-0.7% hermaphrodites; (3) C3H/HeJ and three strains of C57BL produced normal sex ratios and no hermaphrodites; (4) four F1 hybrids produced 44.5-49.2% males and 0.3-1.9% hermaphrodites; (5) the seven CXB RI strains produced perplexing sets of data: 26.5%-52.0% males and 0.2-3.2% hermaphrodites. These results indicate that a partly dominant gene favouring non-disjunction occurs in the female genomes of BALB/c and SJL/J strains, an enhancing gene occurs in C57BL/6By and there may be others. Heterosis appears to favour normal mitosis. CXBH females produced 26.5% males and 3.2% hermaphrodites, indicating that non-disjunction may have occurred in every male zygote, thus providing models for the generation of Turner's syndrome, hermaphroditism and a predictable non-disjunction. Reciprocal crosses were made between SJL/J and BALB/cBm, followed by 20 backcrosses to the maternal strains, to exchange the Ys and produce two new consomic strains. Males from SJL-BALB/cBm-Y strain, when mated to CXBH females, sired 34.3% males and 4.3% hermaphrodites, whereas BALB/cBm-SJL-Y sired no hermaphrodites and the sex ratio of the offspring was normal. This shows that the non-disjunction involves only the BALB/cBm Y chromosome and is completely independent of genes on the X or autosomal chromosomes. These results indicate that the BALB/cBm Y chromosome is unable to interact normally with the mitotic spindles of some genotypes, particularly CXBH, BALB/c and SJL. The simplest hypothesis is that a primary non-disjunction occurs at first cleavage. This can produce an array of mosaics determined by chance in the many sampling events that take place during development and by the relative vigour and stability of the two original clones.
Adsorption of fetal surfactant protein SP-B on the human amnion at term and on amniocytes incubated with fetal surfactant in vitro
Authors: Newman GE , Phizackerley PJ , Lopez Bernal A , Noble GR , Willis AC
Published: October 2005

Fetal surfactant stimulates the synthesis of prostaglandins by slices of human amnion at term and by a human amnion cell line, and these effects are partly dependent upon surfactant apoproteins. In this paper, methods are described for the purification of surfactant from human amniotic fluid and from post-mortem human lung. A procedure is described for the purification of surfactant protein SP-B from human amniotic fluid, and the sequence of 20 amino acids at the N-terminal has been determined. A monoclonal antibody generated against human lung surfactant has been shown to react with SP-B from amniotic-fluid surfactant, and the presence of SP-B on the surface of the amnion at term has been demonstrated by immunohistochemical methods. It has also been shown that SP-B from surfactant is present on the surface of amniocytes incubated with surfactant in vitro.
Neonatal consequences of placental and membrane dysfunction
Authors: Yu VY
Published: October 2005

Early amnion rupture is a sporadic event that results in mechanical teratogenesis due to amniotic-band disruption and/or compression. It may cause abortion or stillbirth, craniofacial clefts, and cerebral, body wall and limb/skeletal defects. Prolonged and premature rupture of membranes and oligohydramnios result in the dry-lung syndrome and pulmonary hypoplasia. The risk of chorioamnionitis is also increased, with serious consequences to the fetus and neonate. Placental lesions are associated with fetal growth retardation, preterm birth, fetal malformations and other neonatal disorders (congenital infections, erythroblastosis, alpha thalassaemia). In particular, the impact of extremely preterm births on perinatal mortality rates and health costs is substantial. The 1-year survival rate of singleton infants born at the Monash Medical Centre was 10% at a gestation period of 23 weeks, 37% at 24 weeks, 42% at 25 weeks, 61% at 26 weeks and 78% at 27 weeks (11% at birthweights of 500-599 g, 30% at 600-699 g, 55% at 700-799 g and 71% at 800-899 g). Proven measures to minimize the neonatal consequences of extremely preterm delivery include in utero transfer of at-risk fetuses to a perinatal centre and antepartum corticosteroids. Research into the pathophysiological basis of placental and membrane dysfunction may help reduce the prematurity rate.
Ovarian follicular dynamics and concentrations of oestradiol-17 beta, progesterone, luteinizing hormone and follicle stimulating hormone during the periovulatory phase of the oestrous cycle in the cow
Authors: Kaneko H , Terada T , Taya K , Watanabe G , Sasamoto S , Hasegawa Y , Igarashi M
Published: October 2005

Changes in the plasma concentration of oestradiol-17 beta, progesterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were characterized during the transition from the luteal to the follicular phase, the periovulatory period and the early luteal phase in five cycling cows. The pattern of growth and the regression of follicles and corpora lutea in the ovary of the same animals were also assessed by daily ultrasonographic examinations. Two waves of follicular growth (ovulatory and non-ovulatory) occurred in all animals. The ovulatory follicular wave started from 4 days before the preovulatory surges of LH and FSH and the wave of next growth of a dominant follicle (non-ovulatory follicle) started within one day after ovulation. Changes in plasma levels of oestradiol-17 beta correlated well with the growth of both ovulatory and non-ovulatory dominant follicles. Suppression of FSH concentration during the follicular phase was inversely related to the increase in plasma concentration of oestradiol-17 beta. These results suggest that, in the cow, ovulatory dominant follicles suppress FSH secretion by increasing the concentration of oestradiol-17 beta (and probably also inhibin) during the follicular phase.
Peripheral concentrations of immunoreactive inhibin during pregnancy and parturition in the ewe
Authors: Findlay JK , Doughton BW , Russell DL
Published: October 2005

The aim of this study was to measure the peripheral concentrations of immunoreactive inhibin (ir-inhibin) and progesterone (P) during pregnancy and parturition in the ewe and to relate the concentrations of ir-inhibin to P and to the number and sex of the fetuses. P increased across pregnancy with higher levels in ewes with 2 fetuses (n = 5) than in those with 1 fetus (n = 6), and concentrations falling before birth. ir-Inhibin concentrations were relatively stable during the first 40 days of pregnancy for example (Day 20, 34.7 +/- 2.9 pmol L-1; mean +/- s.e.m., n = 11). After Day 40, inhibin fell in all ewes to reach less than or equal to 2.5 pmol L-1 after Day 80 (mean on Day 103, 6.3 +/- 1.2 pmol L-1), and remained low until 2 days before parturition when concentrations rose sharply, peaking at or around the day of birth in all ewes (21.5 +/- 2.1 pmol L-1). Thereafter, ir-inhibin fell and remained low or undetectable for up to 10 days in the six ewes still being sampled. ir-Inhibin concentrations in ewes carrying one (n = 6), two (n = 5) or three fetuses (n = 1) did not differ at any stage of pregnancy examined. The sex of the fetus did not appear to influence the peripheral concentrations of ir-inhibin in the ewe.
Application of reproductive technology to the Australian livestock industries
Authors: Evans G
Published: October 2005

Current use of reproductive technology in the Australian livestock industries is limited, though it increased in line with higher prices for beef and wool through the 1980s. The required techniques, many of which were developed in Australia, are available and the level of expertise is comparable to the best in the world. However, the extensive pastoral industries do not readily lend themselves to these procedures. Only in the dairy industry is artificial insemination used to a significant degree. On the other hand, application of the technology in the pastoral industries is confined largely to studs and breeding cooperatives which provide breeding animals for producer flocks and herds. Hence the impact of applied technology may be more widespread than first appears. Until recently, little regard was paid to application of the technology along sound breeding principles. Artificial insemination and multiple ovulation and embryo transfer (MOET) have not been used so much in planned breeding programmes aimed at local improvement of stock, but more to proliferate genes of reputedly superior stock, imported either from overseas or elsewhere in Australia. This is particularly true of MOET, where the incentive to use it is commonly a short term cash gain made from proliferating breeding stock of a particularly valuable and usually novel strain or breed. Recent technological improvements which render the use of reproductive technology cheaper and more effective will lead to its more widespread use in commercial practice. Techniques for embryo freezing and splitting have been greatly simplified and quickly put into practice. The novel livestock technologies of in vitro oocyte maturation and fertilization have already found commercial application overseas. Fecundity-enhancing products have also been adopted by the livestock industries. There is potential value for greater use of reproductive technology in the livestock industries provided it is implemented according to sound breeding principles and provided associated management practices are applied simultaneously.
Morphometry of the epididymis of the tammar wallaby, Macropus eugenii, and estimation of some physiological parameters
Authors: Chaturapanich G , Jones RC
Published: October 2005

About 14 ductuli efferentes (mean length 48 cm) leave the testis of the tammar. The caput, corpus and cauda epididymidis constitute 37%, 42% and 21% respectively of the total length of the ductus epididymidis (estimated to be 34.9 m long). The initial segments of the ductus epididymidis are longer, relative to body or testis mass, in the tammar than in eutherian mammals such as the rat. The main morphometric features of the male excurrent duct system of the tammar are a high ratio of surface area of luminal border:luminal volume of the ductuli efferentes (which reabsorb most of the fluid leaving the testis), a high ratio of epithelial volume:luminal volume in the caput and corpus epididymidis (which are involved in sperm maturation) and a low ratio of epithelial volume:luminal volume in the cauda epididymidis (which is involved in sperm storage). Estimates of fluid reabsorption by the ductuli efferentes and protein secretion by the caput epididymidis were respectively 8.9 microL cm-2h-1 and 2.8 micrograms cm-2h-1. Other estimates for the ductuli efferentes, caput, corpus and cauda epididymidis respectively were: sperm velocity (4.5, 4.8, 2.2, and 0.9 mm min-1), duration of sperm transit (107 min, 1.9 days, 4.7 days, and 6.3 days), total number of spermatozoa (4950 x 10(6)) and distribution of extragonadal spermatozoa (0.6, 14, 36 and 49% of the total). The values are within the ranges estimated for eutherian mammals.
Immunization of merino ewes with a synthetic inhibin peptide or with preparations obtained from bovine and porcine follicular fluids by immunoaffinity chromatography result in different effects on ovulation rate and on plasma gonadotrophin concentrations
Authors: O'Shea T , Andrews CM , Bindon BM , Hillard MA , Miyamoto K , Sinosich MJ
Published: October 2005

Ewes were immunized with either a synthetic peptide (peptide 1-32) that has an amino acid sequence identity with the first 32 amino acids at the amino terminal of the alpha-subunit of porcine inhibin, or with bovine or porcine monoclonal antibody purified inhibin (bMPI and pMPI respectively), obtained by immunochromatography from follicular fluids. The peptide 1-32 was conjugated to albumin before use. Peptide 1-32 and bMPI increased ovulation rate and number of follicles (greater than or equal to 5 mm diameter). Although bMPI increased plasma FSH concentration the peptide did not. pMPI had no effect on ovarian activity but markedly elevated both plasma FSH and LH concentrations. The plasma LH concentration was lowered in ewes immunized with peptide 1-32. It appears, therefore, that ovulation rate can be increased following increased plasma FSH concentrations at luteolysis or in the absence of such an increase. Conversely, greatly increased plasma gonadotrophin concentrations at luteolysis (pMPI) were not followed by an increase in ovulation rate. Antibodies in the plasma of ewes immunized with peptide 1-32 and bMPI bound to iodinated synthetic human inhibin alpha-chain 6-30 peptide. The results suggest that ovulation rate is at least partly determined by intraovarian factors.
Concentrations of immunoactive inhibin in serum during human pregnancy: evidence for an ovarian contribution
Authors: Yohkaichiya T , Polson D , O'Connor A , Bishop S , Mamers P , McLachlan V , Healy DL , de Kretser DM
Published: October 2005

Immunoactive inhibin (ir-inhibin) concentrations in maternal serum during normal human pregnancy have been established in two separate studies employing cross-sectional and longitudinal sampling regimes. Ir-inhibin concentrations rose from the mid-luteal phase (geometric mean + 95% confidence intervals 1.490 (1.086-2.028) U mL-1) to peak at week 11 of gestation (3.77 (3.26-4.35) U mL-1), declined to a plateau from 14 to 25 weeks with means ranging from 1.8 to 2.3 U mL-1, and subsequently rose slowly to a peak of 6.53 U mL-1 at 41 weeks. In the longitudinal study, similar results were obtained and no differences were found in maternal inhibin levels in women carrying male or female fetuses. Paired cord blood and maternal samples showed no significant difference in ir-inhibin concentrations irrespective of the sex of the fetus. However, in all such pregnancies amniotic fluid ir-inhibin levels were 2-3 fold greater than maternal or fetal levels raising the possibility that the amnion may secrete inhibin. In 12 women without functional ovaries in whom a singleton pregnancy was achieved by donation of oocytes and in vitro fertilization, the ir-inhibin levels showed a similar pattern in the first trimester of pregnancy but the concentrations achieved were markedly lower (peak 1.1 U mL-1 at 9 weeks). In five women from the group in whom samples were available late in gestation, three showed greater than normal levels and two had subnormal levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Seasonal prolactin secretion and its role in seasonal reproduction: a review
Authors: Curlewis JD
Published: October 2005

The majority of seasonally breeding mammals show a seasonal pattern of prolactin secretion with peak concentrations in spring or summer and a nadir in autumn or winter. Photoperiod influences prolactin secretion via its effects on the secretion of the pineal hormone melatonin. Preliminary evidence suggests that the effects of melatonin on both prolactin and gonadotrophin secretion are via a common target area, possibly within the anterior hypothalamus, and that differences in response to photoperiod may be due to differences in the processing and/or interpretation of the melatonin signal. In contrast to seasonal gonadotrophin secretion, the seasonal changes in prolactin are not due to changes in the sensitivity of a feedback loop and so must be due to direct effects on the hypothalamic pathways that control prolactin secretion. Little else can be said with confidence about the neuroendocrine mechanisms that lead to the seasonal changes in prolactin secretion. Dopamine and noradrenaline turnover in the arcuate nucleus and median eminence decrease under short daylength. If catecholamine turnover in these structures is positively correlated with catecholamine concentrations in the long or short hypophysial portal vessels, it is unlikely that the decrease in prolactin concentration in winter is due to the effects of increased concentrations of dopamine or noradrenaline in the portal vessels. There is, however, evidence for increased pituitary sensitivity to dopamine under short daylength, so increased dopamine concentrations may not be required for suppression of prolactin secretion at this time. In addition to the diminished secretion of prolactin under short daylength, rate of prolactin synthesis and pituitary content of prolactin also decline although the mechanisms that regulate these changes are poorly understood. Although all seasonal breeders show a seasonal change in prolactin secretion, there are continuously breeding species in which prolactin secretion is also under photoperiodic control. It is likely therefore that a seasonal pattern of prolactin secretion is only evidence of neuroendocrine sensitivity to changing photoperiod. Depending upon the species, this sensitivity to the seasonal changes in daylength may or may not be accompanied by seasonal changes in a biological endpoint such as seasonal reproduction or indeed other adaptations. Whether the seasonal change in prolactin secretion is an endocrine mediator of such adaptations remains in contention. Certainly in some species this signal does have a role in reproduction. For example, in species with an obligate seasonal embryonic diapause, the seasonal increase in prolactin can act as a luteotrophin (mink and western spotted skunk) or luteostatin (Bennett's and tammar wallabies.(ABSTRACT TRUNCATED AT 400 WORDS)
Effects of the ovary, sucking stimulus and season on the pattern of LH and FSH release in the female tammar, Macropus eugenii
Authors: Hinds LA , Diggle PJ , Tyndale-Biscoe CH
Published: October 2005

The sequential effects of removal of the corpus luteum, removal of the non-luteal ovary and sucking stimulus and the effects of season of the year on the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) have been determined in the tammar wallaby, Macropus eugenii. Plasma concentrations of LH and FSH were measured at 15 min intervals for 6 h in eight animals at four successive times in the breeding season (lactational quiescence); (A) while they were intact and lactating, (B) 10 days after removal of the ovary bearing the quiescent corpus luteum, (C) 21 days after bilateral ovariectomy and (D) 21 days after removal of the sucking stimulus, and (E) in the following non-breeding season (seasonal quiescence). Single blood samples were taken twice weekly during lactational quiescence. In the presence of ovarian tissue, basal concentrations of LH were low (0.94 ng mL-1) with pulses of low magnitude (1.3 ng mL-1) and low frequency (1.4 pulses per 6 h). There was no response to luteectomy but all three parameters increased after bilateral ovariectomy. Removal of the sucking stimulus affected the LH pulse frequency but seasonal differences were not evident. The pattern of release of FSH was not pulsatile. There was no response to luteectomy in basal concentrations of FSH but these rose significantly after bilateral ovariectomy (P less than 0.001) in lactational quiescence. There was no effect of removing the sucking stimulus but in seasonal quiescence concentrations were higher. The results indicate that non-luteal ovarian tissue is essential for the negative-feedback effects on LH and FSH secretion, that the pattern of release of LH, but not FSH, is pulsatile, and that there is no marked seasonal change in hypothalamo-hypophysial activity.
Maternal recognition of pregnancy in the Tasmanian bettong, Bettongia gaimardi (Marsupialia: Macropodoidea)
Authors: Rose RW
Published: October 2005

The fetus of the marsupial Bettongia gaimardi, the Tasmanian bettong, has both morphological and cytological effects upon the gravid uterus. Development of diapausing embryos or the initiation of oestrous cycles was achieved by removal of the pouch young (RPY). Increases in the diameter of the uterine basal endometrial glands were noted 3 and 4 days later. An animal at Day 5 after RPY had glands in the gravid uterus that were significantly larger than those in the non-gravid uterus (P less than 0.01). This difference was also found in non-pregnant animals before Day 11 and was believed to be due to the local presence of the corpus luteum. Thereafter, significant differences were only found in pregnant animals until parturition at Day 17 or 18 after RPY. These differences were attributed to the local effect of the fetus and reflect a 'maternal recognition of pregnancy', as found in other macropodoid species.
Acute effect of PMSG on ovarian androgen-binding sites in the intact immature female rat
Authors: Campo S , Carson RS , Findlay JK
Published: October 2005

Androgen-binding activity in ovaries containing only immature follicles is compared with that in ovaries stimulated with pregnant mare serum gonadotrophin to induce development of large preovulatory follicles. The androgen-binding sites present in cytosols prepared from unstimulated ovaries exhibited kinetics, affinity and a range of specificities for natural and synthetic androgens consistent with those exhibited by the androgen receptor isolated from androgen-sensitive tissues. Studies of sedimentation and DNA binding suggest that the receptor-like androgen-binding site present in unstimulated ovaries exists as the 'non-activated' form which is able to undergo transformation and bind to nuclear DNA. Properties of the androgen-binding sites isolated from ovaries stimulated with gonadotrophin were very different from those of the androgen receptor present in unstimulated ovaries. Specificity for androgens was reduced, capacity for dihydrotestosterone (DHT) and methyltrienolone (R1881) increased and androgen-binding activity was associated exclusively with the 4.5S form which was not able to bind to nuclear DNA. These data confirm that a shift from a receptor-like to a nonfunctional androgen-binding site is associated with the development of ovulatory follicles and suggest that shifts in androgen-binding populations will determine the response of developing ovarian follicles to androgens.
Control of inhibin production by dispersed human luteal cells in vitro
Authors: Wang HZ , Lu SH , Han XJ , Sun ZD , Shen WX , Zhou W , Bangah ML , Findlay JK
Published: October 2005

The production of inhibin in vitro by dispersed cells from early to mid (Days 16-19) and late stage (Day 23) human corpus luteum (CL) was examined, and the effects of human chorionic gonadotrophin (hCG), follicle stimulating hormone (FSH), oestradiol and testosterone on inhibin production were determined. Corpora lutea from five subjects in the early to mid luteal stage and three subjects in late luteal stage were dispersed with enzymes and the luteal cells cultured in medium supplemented with 5% calf serum and either FSH (1, 10 or 100 ng mL-1), oestradiol-17 beta (2.5, 5 or 10 micrograms mL-1) or testosterone (0.25, 1 or 5 micrograms mL-1) with or without hCG (1 I.U. mL-1). Cells were cultured for 1 to 3 days without changes of medium, and the concentrations of progesterone, oestradiol and immunoreactive inhibin in the medium were measured by radioimmunoassay. Cells from both types of CL produced inhibin in vitro under basal conditions, but only cells from early to mid CLs responded to hCG with a significant increase in inhibin production. Both progesterone and oestradiol production were stimulated by hCG in both groups of CL. Inhibin concentrations in the cell cultures declined with time in culture, particularly in the late CL group, whereas the concentration of steroids increased. Neither FSH, oestradiol nor testosterone significantly changed inhibin production in either CL group. It was concluded that inhibin production by human luteal cells in vitro is influenced by the age of the CL, and is dependent on LH (hCG) but not on FSH or sex steroids.
Corpus luteum and endometrial function in ewes post partum: a study in vivo and in vitro
Authors: Wallace JM , Ashworth CJ , Aitken RP , Cheyne MA
Published: October 2005

Induction of ovulation post partum is associated with a high incidence of prematurely regressing corpora lutea. However, inadequate luteal function is not the sole reason for pregnancy failure, because ewes with normal corpus luteum function and successful fertilization also fail to establish pregnancies. The effects of suckling status and the interval from post partum to rebreeding on corpus luteum and endometrial function were examined in vivo and in vitro. Ewes were weaned early or allowed to lactate, induced to ovulate using a progesterone-impregnated controlled internal drug release device and an intramuscular injection of pregnant mare serum gonadotrophin, and inseminated (intrauterine) at either 21 or 35 days post partum (n = 10 per group). A further 10 standard ewes whose interval from parturition was in excess of 150 days were included for comparative purposes. On Day 10 after insemination the pregnancy rate was determined in four ewes from each of the post-partum groups and five standard ewes. These ewes were then ovariectomized and hysterectomized for studies in vitro. The incidence of premature luteal regression, as assessed by progesterone concentrations in peripheral blood was independent of the suckling stimulus but dependent on stage post partum (21 days post partum, 6 of 19 ewes; 35 days post partum, 0 of 19 ewes; P less than 0.05). Luteal function was normal in all standard ewes. Ovulation rate, corpus luteum weight, corpus luteum progesterone content and basal progesterone production in vitro were significantly less in 21-day than in 35-day post-partum ewes. Pregnancy rates as determined on Day 10 or at term were low in all post-partum groups (7 out of the 38 ewes inseminated) compared with standard ewes (8 of 10). Uterine function was assessed by culturing endometrial tissue from the tip and body of each uterine horn in the presence of [3H]leucine for 30 h at 37 degrees C. Incorporation of radiolabel into non-dialysable proteins synthesized and secreted by the endometrium in vitro was independent of uterine horn location and suckling status but was significantly lower (P less than 0.001) in media from 21-day than from 35-day post-partum ewes. Irrespective of treatment group, incorporation of radiolabel was positively correlated with mean plasma progesterone concentrations on Days 2-10 after insemination and with basal progesterone production in vitro. Secreted proteins were detected by two-dimensional-polyacrylamide-gel electrophoresis and fluorography.(ABSTRACT TRUNCATED AT 400 WORDS)
Stimulation of protein synthesis and expansion of pig blastocysts by insulin in vitro
Authors: Lewis AM , Kaye PL , Lising R , Cameron RD
Published: October 2005

Present evidence indicates that insulin may act as a growth factor during preimplantation development. This hypothesis has been tested on pig blastocysts by determining the effect of insulin on protein synthesis and blastocyst expansion over 24 h. Blastocysts were collected from superovulated gilts or sows on Day 5 or 6 and incubated overnight in a modified BMOC2 medium. Those that were cultured with 1.7 nM insulin had 14% larger radii, and were 36% more active in their incorporation of [3H]leucine (protein synthesis) than those that had been cultured in non-supplemented medium. There was a significant linear correlation between the rate of protein synthesis and the radius of blastocysts when all blastocysts and only those cultured with insulin were examined, but the correlation for the blastocysts in non-supplemented medium was just outside statistical significance. The regression coefficient for the insulin-treated blastocysts was 132% of that for blastocysts cultured in unsupplemented medium; this suggests that insulin increased the size of blastocysts and the rate of protein synthesis per unit size. The results indicate that pig blastocysts respond to physiological levels of insulin in similar fashion to those of mice and cattle, supporting the hypothesis that insulin may act as a general embryonic growth factor. Because of the cross reaction between the insulin receptor and the ligands, insulin and insulin-like growth factor 1 (IGF-1), the results also suggest that IGF-1, reported to be present in pig uterine fluid, could be involved in this stimulation in utero.
Comparison of a swim-up technique with the Hamilton Thorn Motility Analyser for measurement of sperm velocity and motility
Authors: Suttiyotin P , Thwaites CJ
Published: October 2005

A colorimeter-based swim-up (SU) technique was developed and compared with a Hamilton Thorn Motility Analyser (HTM) for the evaluation of ram semen. SU parameters (sperm velocity in microns s-1, proportion of rapidly moving spermatozoa, and motility index) were significantly correlated (r from 0.47 to 0.98, P from < 0.05 to < 0.001) with most HTM parameters in semen containing known proportions of motile and immotile spermatozoa and in semen that was cold shocked, aged, diluted-stored and frozen-thawed. There were, however, no significant correlations between sperm velocity and HTM parameters in the fresh semen studied, possibly because of the small number of observations (n = 21) and narrow range of semen quality (83 +/- 2% subjectively scored motility) available. It is concluded that the swim-up technique is a simple, cheap, objective and reliable means of measuring sperm velocity and motility in ram semen.
Differential mRNA expression of the phosphoprotein p19/SCG10 gene family in mouse preimplantation embryos, uterus, and placenta
Authors: Pampfer S , Fan W , Schubart UK , Pollard JW
Published: October 2005

The p19/SCG10 gene family encodes two structurally related cellular proteins that are implicated in signal transduction during differentiation of mammalian cells. Previous evidence suggests that both genes are expressed in a stage-specific manner but that expression of p19 is widespread, whereas that of SCG10 is restricted to developing neurons. To determine at which developmental stage these two genes are first expressed, we have probed for mRNA transcripts in preimplantation embryos and the utero-placental unit of the mouse. As determined by polymerase chain reaction (PCR) to amplify reverse-transcribed RNA, expression of both genes was detected in preimplantation embryos, although the temporal pattern was distinct. p19 mRNA appeared transiently in 2-cell embryos, was undetectable in morulae and early blastocysts and reappeared in expanded blastocysts. In contrast, embryonic expression of SCG10 mRNA commenced in morulae and was maintained through to the blastocyst stage. Interestingly, only SCG10 expression could be detected in blastocysts derived from cultures of 2-cell embryos. During the post-implantation period, SCG10 transcripts were only detected in the uterus and placenta by reverse transcriptase-PCR, whereas p19 mRNA could be detected by Northern blotting and showed stage-specific expression in both tissues. The data confirm that, at later developmental stages, expression of p19 is widespread while that of SCG10 is more restricted. The expression of both genes in preimplantation embryos suggests distinct but possibly overlapping roles for p19 and SCG10 in early mammalian development.
Duration of the cycle of the seminiferous epithelium and quantitative histology of the testis of the South American white-belly opossum (Didelphis albiventris), Marsupialia
Authors: Queiroz GF , Nogueira JC
Published: October 2005

The duration of the cycle of the seminiferous epithelium of the South American white-belly opossum, as obtained by autoradiography after intratesticular injection of tritiated thymidine, was estimated to be 17.3 +/- 0.1 days (mean +/- s.d.). Quantitative histological analysis was performed on testes from animals caught both in mating and non-mating periods of the annual reproductive cycle. Significant differences were found in the volumetric proportion of Leydig cells, but the spermatogenic yield remained constant throughout the year. The numerical ratio between type A spermatogonia and zygotene primary spermatocytes (1:12.0), as well as daily sperm production (4.8 x 10(6) sperm cells per g of testis parenchyma per day), were found to be lower than those reported in most eutherian mammals.
Effect of ovariectomy on blastocyst expansion and survival in ferrets (Mustela putorius furo)
Authors: McRae AC
Published: October 2005

The initial objective was to investigate whether progesterone alone can support full blastocyst expansion in ferrets ovariectomized on Day 5 post coitum (p.c.). By Day 11 p.c. blastocysts from control animals had expanded to approximately 2000 microns in diameter, whereas by Days 11 or 14 p.c. blastocysts from ovariectomized animals given progesterone had diameters of < 1000 microns. Thus, ovarian factors in addition to progesterone are apparently required for normal blastocyst expansion in this species. Subsequent experiments indicated that an initial stage of expansion (from approximately 200 microns to approximately 400 microns) occurred regardless of whether ovariectomy was performed on Day 2 or 3 p.c. A second stage of expansion resulted in blastocysts of approximately 700 microns in diameter and it occurred in ovariectomized animals if progesterone was given or if ovariectomy was delayed until Day 5 p.c. A third phase of expansion resulted in blastocysts of approximately 2000 microns in diameter and occurred only if ovariectomy was delayed until Day 8 p.c. Although blastocyst expansion appeared normal in these animals, implantation did not occur in the absence of progesterone replacement. In addition, blastocysts retained in the oviduct by ligation of the uterotubal junction failed to expand beyond approximately 400 microns in diameter. These results suggest that progesterone acts upon the uterus to promote blastocyst expansion up to a diameter of approximately 1000 microns and that additional ovarian factors are required for further blastocyst expansion.
Morphometric and freeze fracture studies of human endometrium during the peri-implantation period
Authors: Rogers PA , Murphy CR
Published: October 2005

This paper reviews recent morphological work on peri-implantation endometrium collected from the Monash University In vitro Fertilization (IVF) Programme. Comparisons of endometrial tissue collected from women who had undergone different superovulation regimens demonstrated that significant structural differences could be detected by morphometry and ultrasound, but not by routine histopathology. Morphometric studies on endometrium from agonadal women receiving hormone replacement therapy demonstrated major differences between women with identical endocrine profiles. A biopsy inadvertently taken from one of these patients at the time of implantation was not of the appearance classically believed to be associated with receptivity for implantation. Studies have shown that the tight junction structure of endometrial epithelium is regulated during the menstrual cycle, suggesting that the integrity of the epithelial barrier may be important in the preparation of the endometrium for implantation.
Embryo-derived platelet activating factor
Authors: O'Neill C
Published: October 2005

Platelet-activating factor (PAF) is secreted by the preimplantation embryo of a number of species. The role of this secretion is yet to be fully elucidated. Evidence to date indicates that it has an important function as an autocrine stimulant of embryonic metabolism, growth and viability. Production of PAF by embryos appears to be severely compromised in vitro. This may be a major cause of reduced embryo viability following embryo culture and it may also help to explain the controversy in the literature regarding the production of PAF by embryos. PAF also alters several aspects of maternal physiology during early pregnancy including endometrial prostaglandin secretion. The significance of these changes remains to be defined.
Roles of prostaglandins (PG) F2 alpha, E1, E2, adenosine, oestradiol-17 beta, histone-H2A and progesterone of conceptus, uterine or ovarian origin during early and mid pregnancy in the ewe
Authors: Weems CW , Vincent DL , Weems YS
Published: October 2005

Pregnancy does not prevent the local transfer or accumulation of prostaglandin F2 alpha (PGF2 alpha) by the corpus luteum (CL), the number of receptors for PGF2 alpha or the binding of PGF2 alpha to the CL. However, the conceptus does depress the response of the CL to PGF2 alpha during early pregnancy. PGE1 and PGE2 appear to be blood-borne antiluteolysins that are delivered locally to prevent the actions of PGF2 alpha during early pregnancy, since they prevent luteolysis only when given by chronic intrauterine infusion adjacent to the ovary with the CL. The concentrations of PGE1 and PGE2 in the endometrium and PGE2 in uterine venous plasma increase during early pregnancy. A Day 10 embryo transferred to a Day 6 progestagen-primed recipient ewe advances the time at which PGE2 is secreted. The uterine venous PGE/PGF2 alpha ratio is 12:1 at midgestation, and exogenous PGF2 alpha increases the placental secretion of oestradiol-17 beta. This is followed by increases in PGE secretion when endogenous PGF2 alpha increases. Both oestradiol-17 beta and PGE may protect placental secretion of progesterone from PGF2 alpha, since PGF2 alpha causes the CL to regress but does not affect placental progesterone or pregnancy in the presence or absence of the ovary.
Nutrition-progesterone interactions during early pregnancy in sheep
Authors: Parr RA
Published: October 2005

A series of studies was undertaken to determine the relationship between level of feed intake during early pregnancy, concentrations of peripheral progesterone and embryo survival in sheep. Ewes fed twice maintenance (2M) rations after joining had a pregnancy rate of 48%. Ewes fed 2M rations and given exogenous progesterone between 8 and 14 days after mating had a pregnancy rate of 76%. Ewes fed rations calculated to maintain live weight (maintenance, M) or fed restricted rations during this same time had pregnancy rates ranging from 60 to 68%, with no beneficial effect of progesterone supplement. Concentrations of peripheral plasma progesterone on Day 12 after mating were inversely related to the level of feed intake; this relationship reflected an increase in the metabolic clearance rate of progesterone with increased feed intake (1/2M, M and 2M) without concomitant changes in the entry rate of the hormone. Injection of epostane, an inhibitor of the enzyme 3 beta-hydroxysteroid dehydrogenase, caused 'windows' of progesterone reduction for 48-h periods over Days 9-13 after mating. The sheep embryo was sensitive to low peripheral plasma progesterone concentrations only on Days 11 and 12 after mating. Blood flow rates in the portal vein of ewes fed either 1/2M, M or 2M rations for 7 days were directly related to the level of feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)
Endocrine events associated with endometrial function and conceptus development in cattle
Authors: Geisert RD , Morgan GL , Short EC , Zavy MT
Published: October 2005

Regulation and timing of luteolysis during the bovine oestrous cycle is controlled by the initiation and length of progesterone stimulation. Results have demonstrated that early administration of progesterone shortens the interoestrous interval in the ewe and cow, and removal of progesterone stimulation through a progesterone receptor antagonist delays luteolysis in sheep. Current data suggest that down-regulation of progesterone receptors in the uterine epithelium may initiate events involved in the synthesis and release of prostaglandin F2 alpha (PGF2 alpha) for luteolysis. Progesterone is also involved in the stimulation of the uterine secretions that regulate conceptus growth and the release of the bovine trophoblast protein-1 (bTP-1) necessary for inhibiting endometrial PGF2 alpha release. Conceptus secretion of bTP-1, a Type I trophoblast interferon, increases the concentration of the cellular enzyme 2',5'-oligoadenylate synthetase within the endometrium. The biological role of 2',5'-oligoadenylate synthetase in the establishment of pregnancy is discussed.
Interaction between oxytocin and prostaglandin F2 alpha during luteal regression and early pregnancy in sheep
Authors: Jenkin G
Published: October 2005

The pulsatile release of oxytocin from the corpus luteum in the sheep is responsible for the pulsatile release of prostaglandin F2 alpha (PGF2 alpha) from the uterus at luteolysis. It has been proposed that PGF2 alpha also reinforces this process by stimulating the release of oxytocin from the corpus luteum. It is, however, unlikely that PGF2 alpha is the major stimulus for oxytocin release at this time. Although the stimulus for the pulsatile release of oxytocin from the corpus luteum appears to reach the ovary from the peripheral circulation, the nature of the stimulus is unknown. Pulses of oxytocin originating from the corpus luteum have also been observed during early pregnancy, but the release of PGF2 alpha, in response to this signal, is abrogated in some way by ovine trophoblast protein-1 (oTP-1). This protein has been shown to inhibit endometrial prostaglandin production and to decrease the amount of PGF2 alpha released in response to oxytocin. Reduction of uterine oxytocin receptor concentrations by conceptus secretory proteins or by interferons related to oTP-1 remains equivocal. Inhibition of uterine oxytocin receptors is, however, probably the major mechanism that prevents luteal regression during early pregnancy. In cyclic sheep the specific inhibition of uterine oxytocin receptors by 1-deamino-2-D-Try (oET)-4-Thr-8-Orn-oxytocin (CAP), a synthetic oxytocin receptor antagonist, inhibits luteal regression and suppresses pulsatile, but not basal, secretion of uterine PGF2 alpha. Thus, the effects of CAP directly parallel the endocrinological changes that occur in early pregnancy in the sheep.
Insulin, insulin-like growth factors and glucose transporters: temporal patterns of gene expression in early murine and bovine embryos
Authors: Schultz GA , Hogan A , Watson AJ , Smith RM , Heyner S
Published: October 2005

mRNA phenotyping by the reverse transcription-polymerase chain reaction (RT-PCR) method was used to compare the patterns of expression of insulin and insulin-like growth factor (IGF) ligand and receptor genes in preimplantation bovine embryos with those established previously for preimplantation murine embryos. In the early bovine embryo, transcripts for IGF-I, IGF-II and mRNAs encoding receptors for insulin, IGF-I and IGF-II were all detectable at all embryo stages from the 1-cell zygote to the blastocyst. In the mouse, IGF-II ligand and receptor mRNAs were not expressed until the 2-cell stage, and the insulin and IGF-I receptor mRNAs were not detectable until the 8-cell stage. Since transcriptional activation of the embryonic genome occurs at the 8- to 16-cell stage in the bovine embryo and at the 2-cell stage in the murine embryo, it is suggested that these transcripts are products of both the maternal and embryonic genomes in the bovine embryo whereas in the mouse they are present only after activation of the embryonic genome. Transcripts for insulin were not detected in preimplantation embryos of either species. Colloidal-gold immunocytochemistry with antibodies directed against the insulin receptor, IGF-I receptor and IGF-I ligand has confirmed the presence of these molecules in bovine blastocysts. RT-PCR and indirect immunofluorescence procedures demonstrated that the glucose transporter (GLUT) isoform 1 is present in murine embryos from the oocyte to blastocyst stage whereas GLUT 2 expression begins at the 8-cell stage.
Intraovarian regulation: the IGF-I example
Authors: Adashi EY
Published: October 2005

A large body of information now supports the existence of an intraovarian system of insulin-like growth factors (IGFs) replete with ligands, receptors, and binding proteins. The intraovarian IGF system is most likely concerned with the amplification of gonadotrophin hormonal action, other potential regulatory roles remaining speculative at this time. There is every reason to believe that work in the next few years will yield the insight necessary to establish whether or not IGFs are truly indispensable to ovarian function; this remains to be demonstrated through selective ablation of ovarian IGF-I gene expression and the examination of the impact of such manipulation on reproductive potential.
Studies on the reproductive performance of Ethiopian sheep by means of an enzyme immunoassay technique; a review
Authors: Mukasa-Mugerwa E , Mutiga ER , Girma A
Published: October 2005

Measurement of the concentration of hormones associated with reproductive function in female animals can aid in the evaluation of their reproductive status. In particular, from the point of view of production, determination of the concentration of circulatory progesterone can aid in the correct assessment of ewes. Many investigators have used radioimmunoassay for this purpose, but the enzyme-linked immunosorbent assay (ELISA) is equally reliable, quicker and cheaper. This report reviews the use of the ELISA in Ethiopian Menz sheep. Progesterone profiles in Ethiopian Menz sheep during pubertal development, the oestrous cycle, pregnancy and post-partum anoestrus were similar to those of temperate breeds. The practical applications of progesterone determination to sheep production and the requirement for the correct handling of samples are emphasized.
Developmentally related changes in the uptake and metabolism of glucose, glutamine and pyruvate by cattle embryos produced in vitro
Authors: Rieger D , Loskutoff NM , Betteridge KJ
Published: October 2005

The metabolism of, and retention of radioactivity from, radiolabelled glucose, glutamine and pyruvate were measured in individual cattle embryos produced in vitro from the 2-cell to hatched blastocyst stage. Uptake was defined as the numeric sum of metabolism and retention of radiolabel. Glucose metabolism increased significantly between the 8- and 16-cell stages, but was accompanied by a much larger increase in glucose uptake. Consequently, the proportion of glucose uptake that was metabolized through the pentose-phosphate and Embden-Meyerhof pathways reached a minimum at those stages. From the compacted morula stage onward, the calculated uptake of [14C]glucose was only 25 to 33% of that calculated for [5-3H]glucose. This suggests that 66 to 75% of glucose carbon leaves the embryo, after metabolism to phosphoenolpyruvate, in some form other than CO2. Little or no glucose metabolism by the Krebs cycle could be detected at any stage. Both glutamine and pyruvate metabolism were relatively high at the 2- and 4-cell stages, declined to a minimum at the compacted morula stage and then increased with blastulation. Glutamine metabolism continued to increase with expansion and hatching of the blastocyst, but pyruvate metabolism did not. This suggest that, relative to the activity of the pathway from pyruvate to 2-oxoglutarate, the activity of the 2-oxoglutarate-to-oxaloacetate segment of the Krebs cycle is of increasing significance during expansion and hatching of the cattle blastocyst.
Interaction of ovary lectin with homologous sperm from Bufo arenarum
Authors: Fink NE , Elola MT , Cabada MO
Published: October 2005

A soluble beta-galactoside lectin purified from Bufo arenarum ovary agglutinated homologous neuraminidase-treated spermatozoa. Microscopic observations of sperm clusters showed that spermatozoa agglutinated in a random way, but the head-to-head type of sperm agglutination was the most common (94-98%). The lectin activity was specifically inhibited by D-galactose and its derivatives, thio-digalactoside being the most active saccharide inhibitor.