Journal of Reproduction and Development
Online ISSN : 1348-4400
Print ISSN : 0916-8818
ISSN-L : 0916-8818
Volume 48, Issue 4
August
Displaying 1-13 of 13 articles from this issue
Review
  • Christopher G. GRUPEN, Mark B. NOTTLE, Hiroshi NAGASHIMA
    Article type: scientific monograph
    Subject area: none
    2002 Volume 48 Issue 4 Pages 313-333
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The mechanism of sperm-induced calcium release has been the subject of many studies since the development in the late 1950s of in vitro culture systems that support mammalian fertilization. Despite efforts to elucidate the nature of the signal from the sperm that triggers both the early and late events of oocyte activation, the precise mechanism remains unresolved. Now, with the advent of somatic nuclear transfer technologies, the need to better understand this unique process has been recognised. Nuclear transfer embryos must be induced to commence development artificially because the activating signal from the sperm is absent. The primary activating stimulus is a large increase in the concentration of intracellular-free calcium and numerous physical and chemical treatments have been found to induce calcium changes that initiate the events of oocyte activation. Although live cloned offspring have been produced in a number of species, the overall efficiencies of the nuclear transfer procedures described thus far are unacceptably low and phenotypic anomalies are common. With the aim of improving these efficiencies, researchers are developing artificial activation treatments which induce oocyte responses that mimic those induced by fertilizing sperm. One strategy is to replicate the pattern of calcium change more closely. Another strategy is to couple an activating stimulus with treatments that inhibit maturation (or M-phase) promoting factor (MPF) activity, which regulates meiotic progression in oocytes. This paper reviews what is understood of calcium release at fertilization and describes the treatments that have been used to induce oocyte activation artificially in parthenogenetic and nuclear transfer studies. The relative effectiveness of the strategies employed to mimic the oocyte's response to sperm are discussed.
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Original Articles
  • Tohru HOSOYAMA, Shigeo KAWADA, Ryosuke OSHIUMI, Sachie YONEDA, Chie SO ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 335-342
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    Growth/Differentiation Factor 8, or GDF-8, is a member of the TGF-β family and is expressed specifically in myogenic precursor cells of the myotome during development as well as in adult axial and paraxial muscles of the mouse. It acts as a negative regulator of skeletal muscle mass, and is known as myostatin. As a part of our studies to elucidate mechanisms underlying the growth of skeletal muscle mass due to physical training in mammals including horses and humans, we isolated and cloned myostatin cDNA from equine (Thoroughbred) skeletal muscles by an RT-PCR method. The base sequence of the entire coding region of equine myostatin cDNA (DDBJ accession no. AB033541) exhibited a high degree of homology to those of other species so far reported. In the deduced amino acid sequence, 4 amino acid positions were unique to the equine myostatin, i. e., Val15 instead of Met, Leu18 instead of Val or Ala, Ala201 instead of Thr, Arg244 instead of Gly or Glu in other species. Western blot analysis of the equine skeletal muscles using anti-myostatin antibody, yielded 3 immunoreactive bands, i. e., 26, 45 and 50 kDa. The band at approximately 26 kDa probably represents mature myostatin and another at approximately 50 kDa corresponds in size to the unprocessed precursor myostatin proteins reported in the literature. Western blot analysis of equine sera of 2 independent breeds, Thoroughbred and Kiso-uma, revealed the possible presence of precursor myostatin proteins at relatively high levels. The molecular identity and the biological significance of serum myostatin immunoreactivities remain to be clarified.
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  • Mariko ITOH, Hisashi KISHI, Ken-ichi OHSHIMA, Satoko KAWAZU, WanZhu JI ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 343-353
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    We studied developmental reproduction of male golden hamsters (Mesocricetus auratus) by determining hormone secretion, observing morphological changes including distribution of immunoexpression of inhibin α subunit, 3β-hydroxysteroid dehydrogenase (HSD), and investigating sperm head count from birth to adulthood. Immunoexpression of inhibin α subunit was found in interstitial cells of not well organized testes of neonatal animals, and positive staining was also found in Sertoli cells in developing animals. However, the intensity of immunostaining in Sertoli cells varied when the spematogenic cycle of the seminiferous epithelium began. Testosterone levels in the plasma and testicular contents of testosterone and immunoreactive (ir)-inhibin increased from around 25 days of age, about 10 days before the presence of the first sperm in the testis. On the other hand, plasma concentrations of ir-inhibin progressively increased from birth to 10 days of age, when it reached peak levels. A reciprocal pattern of change between plasma concentrations of ir-inhibin and FSH was found from 10 days of age. Plasma concentrations and pituitary contents of LH increased from 15 days of age and reached adult levels about 40 days of age. The present results suggest that inhibin is an important factor in the regulation of FSH secretion even in infant male golden hamsters, and the regulated FSH may control the increasing the number of germ cells. Inhibin might be not the only endocrine factor as the regulator of FSH secretion, but also a paracrine or autocrine factor which is involved in spermatogenesis in the golden hamster.
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  • Keiko SHIMIZU, Chihiro KOJIMA, Masahiro KONDO, WanZhu JIN, Mariko ITO, ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 355-361
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    In order to clarify the endocrinological profiles of inhibins during normal menstrual cycles in Japanese monkeys, plasma concentrations of inhibin A and inhibin B were measured by enzyme-linked immunosorbent assay. In addition, circulating gonadotropins and steroid hormones were measured. Blood samples were taken from four Japanese monkeys showing normal menstrual cycles. Plasma inhibin A remained low during the early follicular phase but was high during the luteal phase. Plasma inhibin B was high in the early follicular phase, but fell during the late follicular phase, and remained low during the luteal phase. A significant inverse correlation was observed between plasma concentrations of inhibin B and FSH during the mid-follicular phase, but not between inhibin A and FSH. Plasma inhibin A showed a significant positive correlation with progesterone in the normal menstrual cycle. These results suggest that inhibin B during mid-follicular phase is mainly involved in the suppression of FSH secretion from the pituitary gland, and also that the main source of inhibin A during the luteal phase is corpora lutea in normal menstrual cycle of Japanese monkeys.
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  • Ken-ichi OHSHIMA, Mariko ITOH, Hisashi KISHI, Gen WATANABE, WanZhu JIN ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 363-369
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    To investigate physiological roles of basal levels of circulating LH on follicular development during the second half of pregnancy in golden hamsters, we treated animals with anti-luteinizing hormone (A/LH) or normal horse serum (control serum) at 1100 h on day 12 of pregnancy (day 0 of pregnancy=sperm positive in vaginal smear). Thereafter, changes in plasma concentrations of immunoreactive (ir)-inhibin, estradiol-17β, progesterone and testosterone were determined until 48 h after the treatment; ovaries were also examined immunohistochemically. Furthermore, pregnant golden hamsters were injected with human chorionic gonadotropin (hCG) to determine the effects of immunoneutralization of LH on follicular activity. Plasma concentrations of ir-inhibin and estradiol-17β decreased significantly within 24 h after A/LH treatment, while plasma concentrations of progesterone and testosterone were unchanged. The number of follicles ovulating in response to hCG in the A/LH treated groups (7.0 ± 3.4, n=3) was significantly lower than in the control serum treated group (34.6 ± 4.8, n=5) at 24 h after the treatment. Immunostaining of inhibin α subunit was observed in granulosa cells of healthy and atretic large follicles at 24 h after A/LH treatment, whereas immunopositive reaction of aromatase was not observed in atretic follicles. Positive immunoreaction of 17α-hydroxylase/C17, 20-lyase (CYP17) was observed in theca cells of healthy follicles but not in atretic follicles. These results clearly demonstrate that basal levels of circulating LH are important for maturation of antral follicles and secretion of ir-inhibin and estradiol-17β, but not for progesterone during the second half of pregnancy in the golden hamster.
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  • Mohamed GHANEM, Abedel Hamid SHALABY, Sayed SHARAWY, Nashet SALEH
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 371-375
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The incidence of endometritis and risk factors between herds and between breeds and its effect on the subsequent fertility of cows may differ among countries. It is therefore necessary to study the etiology of endometritis in these different circumstances. This work was carried out on 190 Holstein Friesian cows (2.5-13 years old) belonging to El-Salhia Agriculture project (Ismailia Province, Egypt) during the period from January 1996 to April 1997. The incidence of endometritis was 22.4%, and the most prominent risk factors leading to the occurrence of endometritis were retained placenta, stillbirth, external interference by herdmen during calving and difficult birth (20.6, 19.1, 12.3 and 5.3% respectively). The cows in the first parity had a higher incidence of endometritis (27.7%) than cows in the subsequent parities. Cows which calved in autumn (31.2%) had a higher incidence of endometritis than cows which calved in the other seasons. The endometritic cows had inferior reproductive indices than the normal cows. The interval between calving and first service in cows with endometritis was 14 days longer than the normal ones. The first service conception rate (12.5%) and final conception rate (45.5%) in cows with endometritis were lower than those in the normal cows (50 and 100%) (P<0.05 ). In conclusion the most important risk factors leading to endometritis are retained placenta and abnormal calving in dairy cows in Egypt. Moreover, postpartum endometritis adversely affects subsequent fertility in dairy cows in Egypt.
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  • Keiko SHIMIZU, WanZhu JIN, Chihiro KOJIMA, ZhanQuan SHI, Masahiro KOND ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 377-381
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    Cellular localization of nerve growth factor (NGF) and its receptors (TrkA, p75LNGFR) in the ovary of the Japanese monkey (Macaca fuscata fuscata) was investigated using immunohistochemistry. Strong positive immunostaining for NGF was confined to granulosa and theca cells of large antral follicles in the ovary. The interstitial cells also showed positive immunostaining for NGF. The intensity of immunostaining for TrkA was stronger in granulosa and interstitial cells than in theca cells. Immunoreactions for p75LNGFR were detectable in granulosa, interstitial and theca cells of the ovary. These results strongly suggest autocrine and paracrine regulation of follicular function by NGF in the ovary of the Japanese monkey.
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  • Keiko SHIMIZU, WanZhu JIN, Hisashi KISHI, Junko NOGUCHI, Gen WATANABE, ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 383-391
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    Changes in relaxin concentrations in plasma throughout pregnancy and early lactation up to one month after parturition were characterized in 10 Japanese monkeys by a heterologous radioimmunoassay (RIA) based on the porcine RIA. Plasma levels of LH/monkey chorionic gonadotropin (mCG), estradiol-17β, progesterone and immunoreactive (ir-) inhibin were also monitored for the entire period. Relaxin levels in the plasma were low before conception. An accelerated rise in plasma relaxin levels was found during pregnancy. The first increase was noted during early pregnancy, with a peak (267.5 ± 50.5 pg/ml) at Day 31 ± 2.4 of pregnancy (Day 0= day of LH surge). The second increase was noted just before term with a peak (235.6 ± 37.5 pg/ml). After parturition, relaxin levels in the plasma abruptly declined but were maintained at approximately 100 ng/ml during early lactation. The first rise in plasma relaxin during pregnancy was in parallel with rises of mCG and progesterone, and the second rises was well correlated with those of plasma estradiol-17β ,progesterone and ir-inhibin. These results suggest that the major source of relaxin is corpus luteum and placenta during pregnancy in Japanese monkeys.
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  • Akiko YABUUCHI, Yoko KATO, Yukio TSUNODA
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 393-397
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    Nuclear-transferred mouse eggs receiving embryonic stem cells develop into blastocysts at a high rate, but their potential to develop into fetuses is very low. Therefore, the present study examined the effects of aggregating of two nuclear-transferred eggs at the 8-cell stage to increase the cell number of nuclear-transferred embryos. The proportion of implantation sites on gestational day 10.5 after transfer of aggregated nuclear-transferred embryos (53%) was significantly higher than after single nuclear transfer (29%) or serial nuclear-transfer (37%). The proportion of implantation sites with fetuses did not differ significantly among the three groups (7 to 17%). These results demonstrate that the low potential of nuclear-transferred embryos with embryonic stem cells to develop into fetuses is not due to the lower cell number of nuclear-transferred embryos.
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  • Shelley R. HOUGH, Robert H. FOOTE
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 399-407
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The most effective quantitative separation of ejaculates of semen into subsets of sperm differing in quality by density gradients requires information on the specific effects of processing conditions on sperm density. Reported density of bull sperm varies greatly. This research was undertaken to study the effects of gradient osmolality on sperm density and on separation using gradients with low viscosity and low toxicity to sperm. Semen was available from bulls used for artificial insemination. Cell volume studies revealed that live sperm volume was altered by more than 25% by exposure to solutions differing in osmolality, resulting in predictable differences in density measurable by density gradients. Control studies indicated that discontinuous Nycodenz® gradients differing by less than 1% in density could be prepared. Following centrifugation at 100,000 × g for 1 h fractions containing 96-99% unstained (live) and 91% motile sperm versus a fraction with 100% nonmotile sperm were obtained. The densities (g/ml) of live sperm separated on low osmolality gradients (220-237 mOsm), and on high osmolality gradients (342-345 mOsm) were 1.125 versus 1.145, respectively. Killed sperm on both gradients had a density of 1.233 g/ml. These gradients permit quantitative separation of sperm varying in membrane integrity and ability to function under different conditions, but do not permit sexing.
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  • Masahiro KAWAKAMI, Tetsuya TANI, Xi Jun YIN, Yoko KATO, Yukio TSUNODA
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 409-414
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The effects of oxygen tension (5% and 20%) during in vitro culture of oocytes and fetal fibroblast cells on the developmental potential of parthenogenetic and nuclear-transferred porcine oocytes were examined. The potential of parthenogenetic oocytes matured and cultured under different oxygen tensions to develop into blastocysts was not significantly different (5 to 16%). The proportions of enucleated oocytes receiving fetal fibroblast cells that developed into blastocysts were significantly lower when somatic cells were cultured under low oxygen tension (2 and 3%) than under high oxygen tension (7%). The effects of oxygen tension during culture of oocytes and somatic cells on the developmental potential of parthenogenetic and nuclear-transferred oocytes is discussed.
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  • Wen-Chang ZHANG, Toshihiko NAKAO, Katsuya KIDA, Masaharu MORIYOSHI, Ke ...
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 415-422
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The objectives of this study were to show changes of blood parameters for nutrition during pregnancy and to examine the relationships between the blood parameters and calf birth weights, calf viability, time required for expulsion of fetal membrane, and the fetal membrane weights. Forty-one Holstein Friesian pregnant cows were used. The duration of the dry period was 74 ± 2 (SEM) days. The average milk yield (4% FCM) per cow per lactation for 305 days was 9,795 ± 146 kg. Mean gestation length, body weight of cows at parturition, and cotyledonary weight were 283.7 ± 0.5 days, 761 ± 11 kg, and 1562 ± 33g, respectively. Mean birth weights were 47.4 ± 1.1 kg for female, and 49.8 ± 0.8 kg for male calves. Of the 41 cows, 10 had weak calves and 13 had retained fetal membranes (RFM). No significant effects of parity, bull, lactation length, milk yield, gestation length, cows' body weights, and gender of calves on the cotyledonary and calf birth weights, incidences of neonatal weakness and RFM were shown. Cows showing low plasma glucose and TP concentrations in mid and late lactation periods had lower calf birth weights and cotyledonary weights, and a higher incidence of neonatal weakness. Likewise, cows with low glucose, cholesterol and Ca concentrations in plasma during the late dry period had a higher incidence of RFM. The results indicate that low intake of energy and protein during late lactation and early dry periods adversely affects feto-placental development, leading to neonatal weakness and RFM. Low intake of energy and Ca during the dry period may also cause RFM.
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  • Kaung Huei LIU
    Article type: technical report
    Subject area: none
    2002 Volume 48 Issue 4 Pages 423-430
    Published: 2002
    Released on J-STAGE: August 28, 2002
    JOURNAL FREE ACCESS
    The purpose of the study was to determine and compare the secretion of RBP by bovine spherical, elongating and filamentous conceptuses, and to identify the cellular location of RBP in developing conceptuses by immmunocytochemistry. Bovine conceptuses were removed from the uterus between days 13 and 22 of pregnancy. Events of early bovine embryonic development were observed. The conceptuses underwent a transformation from a spherical to a filamentous morphology during the periattachment period of placentation. Isolated conceptuses were cultured in a modified minimum essential medium in the presence of radiolabeled amino acids. Presence of retinol-binding protein (RBP) in culture medium was determined by immunoprecipitation using bovine placental anti-RBP serum. Presence of immunoreactive RBP in detectable quantities in spherical blastocyst (day 13) culture medium was evident. Increased amounts of RBP were clearly detected in cultures on days 14 and 15, the time of elongating conceptuses. RBP was abundant in cultures on day 22, when the conceptuses were filamentous. Cellular sources of RBP in day 15 and 22 conceptuses were determined by immunocytochemistry with anti-RBP serum. Strong immunoreactive RBP was localized in trophectoderm of day 15 conceptuses, and in epithelial cells lining the chorion and allantois of day 22 conceptuses. RBP originating from the conceptus may serve to transport retinol locally from the uterus to embryonic tissues. Secretion of RBP by spherical blastocysts (day 13) suggests that retinol is needed for initiating the early events of embryonic development. Increased secretion of RBP on days 14 and 15, the time of elongating conceptuses, was coincident with the timing of rapid trophoblast hyperplasia and remodeling. Greater secretion of RBP by the filamentous conceptus (day 22) coincided with the timing of differentiation of the chorion and allantois as well as growth of the embryo proper. Production of RBP by the developing conceptuses may be indicative of an important role for conceptus RBP in the transport, availability and metabolism of retinol during early pregnancy.
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