bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preimplantation embryonic development of spontaneous mouse parthenotes after oocyte meiotic maturation in vitro
Authors: Eppig John J. 
Published: February 2005

AbstractOf eggs ovulated in LT/Sv mice, 10–20% undergo spontaneous parthenogenetic activation, and 40–50% of the parthenotes develop to blastocysts when cultured in simple defined medium from the one‐cell stage. Similar percentages of oocytes isolated from Graafian follicles undergo parthenogenetic activation after spontaneous maturation in simple defined medium, but embryonic development proceeds no further than the two‐cell stage. The simple defined medium that supported preimplantation development of ovulated eggs and spontaneous maturation of extrafollicular oocytes contained no serum, free amino acids, or vitamins. The present experiments were conducted to determine what conditions during spontaneous maturation of extrafollicular oocytes could promote the ability of oocytes to develop to blastocysts after parthenogenetic activation and mimic the environment of preovulatory follicles.Cumulus‐enclosed oocytes that were matured in simple medium supplemented with fetal bovine serum (FBS) developed to blastocysts after spontaneous parthenogenetic activation. Furthermore, minimum essential medium (MEM), a complex medium containing free amino acids and vitamins, could substitute completely for FBS for maturing oocytes from (C57BL/6J × LT/Sv)F1 mice, and to a lesser extent for maturing LT/Sv oocytes. Therefore, even though germinal vesicle breakdown in mouse oocytes and preimplantation development of mouse eggs can occur in the absence of an exogenous supply of free amino acids and vitamins, a complete, or normal, mouse oocyte maturation cannot. These results also demonstrated that gonadotropins are not necessary during oocyte meiotic maturation for parthenogenetically activated eggs to develop through the preimplantation stages.Luteinizing hormone or 17β‐estradiol in MEM during oocyte maturation had no effect on the subsequent development of parthenotes. In contrast, follicle stimulating hormone (FSH) and progesterone in the maturation medium decreased the number of ova that subsequently cleaved, and FSH decreased the number of cleaved eggs that developed to blastocysts.
Sperm abnormalities in the PL/J mouse strain: A description and proposed mechanism for malformation
Authors: Burkhart J. G. , Malling H. V. 
Published: February 2005

AbstractA high frequency (42%) of sperm from the inbred homozygous mouse strain PL/J are abnormal. Head shape abnormalities occur in 15% of the total sperm; and 27% of the sperm are headless, with the mitochondria condensed into a mass at the caudal end of the midpiece region. The sperm without heads exhibit relatively normal motility. Electron microscopy of the testes indicates that some of the abnormal sperm in PL/J males result from a failure of the paired centrioles to attain a normal position on the nucleus opposite the acrosome prior to implantation, or to attach at all. The centrioles that are not attached to the nuclear envelope can differentiate to form the principal piece and midpiece region. The frequency of headless variants in heterozygous F1 indicates that the trait is mainly recessive. The offspring from the backcross of the F1 to homozygous PL/J parents did not give a clear‐cut segregation pattern. The frequency of abnormal sperm in the F1 and the backcross is higher when the female parent is a PL/J.
The movement characteristics of rabbit spermatozoa before and after activation
Authors: Johnson L. L. , Katz D. F. , Overstreet J. W. 
Published: February 2005

AbstractSpermatozoa were flushed with mineral oil from the lower isthmus of the rabbit oviduct at four hours postcoitus (pc) and 11 hours pc. Videotapes were made of sperm behavior in the native isthmic fluid and after dilution of the fluid with culture medium. The tapes showed that, initially, spermatozoa in the native isthmic fluid were virtually immotile, but immediately resumed movement on contact with the culture medium. Isthmic sperm motility then evolved over a five‐ to 10‐minute interval into the characteristic biphasic pattern of activated movement. Cine films of isthmic spermatozoa taken with a high‐speed camera were analyzed to determine flagellar beat frequency, maximum flagellar curvature, and swimming velocity. Progressiveness ratios and hydrodynamic power outputs were then calculated for individual spermatozoa. Two phases of activated sperm movement, a whiplash phase and a progressive phase, were identified and characterized. The power output of activated spermatozoa increased twentyfold in comparison with the preactivated state. The power output of activated spermatozoa did not differ between the two phases of activated movement.
Oocyte maturation inhibitor (OMI) activity in protein granulosa cells
Authors: Centola G. M. , Anderson L. D. , Channing C. P. 
Published: February 2005

AbstractTo determine the origin of oocyte maturation inhibitor (OMI), cumulus‐enclosed porcine oocytes from medium follicles were cultured for two days in Medium 199 alone, the low molecular weight (< 2,000 daltons) fraction of porcine follicular fluid (pFFL), or extracts of granulosa cells from small (1–2 mm), medium (3–5 mm), and large (6–12mm) antral follicles. Additionally, the cumulus‐oocyte complexes were grown in the presence of the low molecular weight fraction of “conditioned” medium from suspension cultures of medium follicle granulosa cells. The percent maturation in cultures with pFFL was significantly (P < .001) less than control cultures. Similarly, addition of the granulosa cell extracts at a 1/20 dilution resulted in a significant reduction in the percent oocyte maturation as compared with controls. The percent maturation after addition of conditioned medium was similarly reduced (P < .001). These results suggest that the granulosa cells probably synthesize and secrete OMI which inhibits oocyte maturation in vitro. Additionally, it appears that the content of OMI in the granulosa cells decreases as the follicle matures.
Acquisition of meiotic competence in the rat: Role of gonadotropin and estrogen
Authors: Bar‐Ami S. , Tsafriri A. 
Published: February 2005

AbstractOocytes were removed from the follicles of rats at 15 to 31 days of age, and their ability to resume meiosis (“meiotic competence”) in vitro was correlated with their diameter and the stage of follicular development. The majority of oocytes explanted on day 15 did not resume meiosis when placed in culture, but the percentage of competent oocytes increased from 14.1% ± 3.0% on day 20 to 67.6% ± 3.3% on day 26 of age. This ability to resume maturation correlated well (r = 0.98) with the increase in diameter of oocytes and coincided with the development of antral follicles.Hypophysectomy on day 15 of age, but not on day 20, reduced the percentage (P < 0.001) and number (P < 0.001) of competent oocytes and was accompanied by a reduction in diameter of oocytes. Treatment with PMSG or E2 increased the number (P < 0.001) and percentage (P < 0.001) of competent oocytes. These results suggest that the ability of oocytes to mature in vitro is dependent upon stimulation by gonadotropins and that this action of gonadotropin may be mediated by production of estrogen within the follicles.
Effect of FSH and HCG on progesterone secretion by cultured oocyte‐cumulus complexes and granulosa cells from porcine antral follicles: Influence of follicular development
Authors: Bae In‐Ha , Channing Cornelia P. 
Published: February 2005

AbstractOocyte‐cumulus complexes and granulosa cells were harvested from small (1–2 mm), medium (3–5 mm), and large (6–12 mm) porcine antral follicles and cultured for 2 and 3 days. The effects of various doses of purified hCG and human FSH on progesterone secretion and monolayer formation were examined. After a 2‐day culture period it was found that FSH was more effective in stimulation of progesterone secretion by cultured oocyte‐cumulus complexes than in granulosa cells harvested from small follicles (P < 0.01), whereas hCG was more effective in stimulating progesterone secretion in granulosa cells than in oocytecumulus complexes harvested from large follicles. In contrast, after a 3‐day culture period, granulosa cells secreted more progesterone compared to oocytecumulus complexes under control conditions or in the presence of hCG or FSH. After 3 days both FSH and hCG stimulated progesterone secretion by oocytecumulus complexes and granulosa cells; however, the hormone effect was greater upon granulosa cells than oocyte‐cumulus complexes. After 3 days of culture in the case of both follicular cell types, there was a greater response to FSH in the case of cells harvested from small compared to large follicles. The reverse was true in the case of hCG responsiveness.Monolayer formation ability of oocyte‐cumulus complexes was greater in the case of complexes harvested from small and medium than complexes harvested from large follicles. Addition of hCG to the cultures led to a dose‐dependent decrease in monolayer formation by oocyte‐cumulus complexes harvested from all sizes of follicles.
Glycosidase and cumulus dispersal activities of acrosomal extracts from opossum (marsupial) and rabbit (eutherian) spermatozoa
Authors: Rodger John C. , Young Ronald J. 
Published: February 2005

AbstractOpossum and rabbit sperm sonicates dispersed the mouse cumulus oophorus in vitro at the same rate on a per sperm basis, despite much higher activities of the glycosidic acrosomal enzymes N‐acetylhexosaminidase (350 ×) and arylsulphatase (40 ×) in the opossum preparation. Activities of another glycosidase, hyaluronidase, and the protease acrosin where similar in sperm extracts from both species. However, specific inhibitors of N‐acetylhexosaminidase (iodoacetate) and arylsulphatase (SO42−, PO43−) markedly reduced the rate of cumulus dispersal by rabbit sperm sonicates. These findings suggest that, while hyaluronidase action probably represents the rate‐limiting (slow) step, several glycosidases act together to disperse the cumulus and in the passage of the fertilizing spermatozoon through it in eutherian mammals. The likely role of these acrosomal enzymes in the marsupial, where the ovulated oocytes lack a cumulus oophorus, is more uncertain.
Promotion of capacitation of guinea pig spermatozoa by the membrane mobility agent, A2C, and inhibition by the disulfide‐reducing agent, DTT
Authors: Fleming A. D. , Kosower N. S. , Yanagimachi R. 
Published: February 2005

AbstractThe membrane mobility agent A2C accelerates the onset of the acrosome reaction of guinea pig spermatozoa by promoting capacitation. Spermatozoa incubated in a suspension of A2C particles in Ca2+‐free medium for one hour undergo a synchronous, rapid acrosome reaction upon the addition of Ca2+. These acrosome‐reacted spermatozoa are capable of fertilization as assessed by their ability to penetrate (fuse with) zona‐free hamster eggs.The disulfide‐reducing agent, dithiothreitol (DTT) inhibits A2C‐mediated capacitation. It also blocks fertilization of zone‐free eggs by acrosome‐reacted spermatozoa by preventing attachment of the spermatozoa to the egg plasma membrane.The mode of A2C action on spermatozoa is compared to that of A2C‐induced fusion in somatic cells. The similarity of the molecular events in the sperm membrane during capacitation and the acrosome reaction to these in other fusion events is pointed out.Inhibition of capacitation by DTT points to the importance of membrane and/or submembrane proteins and thiol groups in this process. Oxidation of sperm membrane SH groups may play an important role in in vivo capacitation.
Identification of surface autoantigens which appear during spermatogenesis
Authors: Romrell Lynn J. , O'Rand Michael G. , Sandow Pamela R. , Porter James P. 
Published: February 2005

AbstractAutoantigens that appear during spermatogenesis in the rabbit were identified using immunoadsorbent chromatography and SDS‐PAGE. To identify cell‐surface proteins, samples of freshly isolated, staged cells were labeled by the lactoperoxidase or Iodo‐Gen iodination procedure and run on SDS‐PAGE. Autoradiograms of the stained, dried gels were prepared. By correlating the band patterns in the SDS gels of immunocolumn and surface‐labeled samples with the band patterns in the autoradiograms, it was possible to show when the autoantigenic proteins appeared on the cell surface. To further support the identification of membrane autoantigens, surface‐labeled, staged cell samples were lysed in Triton X‐100 and immunoprecipitated with antitestis cell autoantisera.Three types of autoantigens have been identified: (1) late class antigens that are present only on late spermatids and epididymal spermatozoa, but are intracellular in early stages, (2) early class antigens which occur on the surface of pachytene spermatocytes and are present throughout subsequent stages of development, and (3) early class, transient antigens, which appear on spermatogenic cells but are not present on epididymal spermatozoa.
Zinc does not inhibit the capacitation of human spermatozoa in vitro
Authors: Blazak W. F. , Overstreet J. W. 
Published: February 2005

AbstractThe effects of zinc on human sperm motility, fertilizing capacity (as assessed by penetration of human spermatozoa into the zona pellucida‐free hamster oocyte), and nuclear chromatin decondensation were investigated using spermatozoa from four fertile donors. Both sperm motility and the penetration of sperm into zona‐free hamster ova were consistently impaired in media containing 1,000 μM zinc. Spermatozoa from one man were similarly affected at a concentration of 500 μM zinc, but no adverse effects were noted at this zinc concentration in experiments with other donors. Since decreased fertilizing capacity in response to zinc was always accompanied by a significant decline in both the percentage of motile cells and mean swimming speeds, it appears that all of these results reflect a general toxic effect on the cells. At lower concentrations (125–250 μM), zinc had no effect on human sperm motility nor their ability to undergo capacitation and penetrate zona‐free hamster ova in vitro. For some donors, zinc (125–500 μM) stimulated both the attachment of spermatozoa to the hamster vitellus and the incorporation of spermatozoa into the hamster ooplasm. The decondensation of human sperm nuclear chromatin in sodium dodecyl sulfate was largely inhibited when zinc was added to the medium, but no significant changes in nuclear stability were apparent after capacitation in zinc‐free medium. We conclude that zinc, when present in subtoxic concentrations, does not adversely affect the ability of human spermatozoa to undergo capacitation and penetrate zona‐free hamster ova in vitro.
Ultrastructure of follicular atresia in the rat
Authors: Gondos Bernard 
Published: February 2005

AbstractObservations were made on the sequence of morphologic changes in atresia of medium‐sized preantral follicles in the rat. Ultrastructural studies indicated that in both control and hormonally treated animals granulosa cell changes, including nuclear condensation and alterations in cytoplasmic organelles, occurred prior to effects on the oocyte. In more advanced stages of atresia, extensive disruption of granulosa cell cytoplasm was associated with loss of microvilli and cytoplasmic vacuolization in oocytes. The findings are consistent with the view that follicular atresia begins with alterations in granulosa cells, effects on the oocyte occurring later in the atretic process.
Influence of luteinizing hormone and progesterone on maturation and fertilizability of rat oocytes in vitro
Authors: Barak Yona , Kaplan Ruth , Kraicer P. F. , Shalgi Ruth 
Published: February 2005

AbstractThe effects of luteinizing hormone (NIH‐bovine LH) and progesterone on maturation in vitro of oocyte‐cumulus complexes from adult proestrous rats were studied by comparing proportions of oocytes showing germinal vesicle breakdown, mucification of the cumulus oophorus, and fertilizability. Addition of either or both of the hormones to the medium in concentrations between 1.25 and 10 μg/ml during maturation had no discernible effect on germinal vesicle breakdown or on fertilization. Mucification was stimulated by LH and even more by LH plus progesterone. It was concluded that maturation in vivo is the result of concerted action of the two hormones. However, addition of LH + progesterone had no effect on the fertilizability of these oocytes. We attribute this to a relative insensitivity of the system for fertilization in vitro to subtle changes in the oocyte.
Stage‐specific changes in protein phosphorylation during preimplantation development in the mouse
Authors: Lopo Alina C. , Calarco Patricia G. 
Published: February 2005

AbstractTo gain insight into the role of protein phosphorylation during early mammalian development, seven mouse preimplantation stages were metabolically labeled with radioactive orthophosphate and the radiolabeled proteins identified using gel electrophoresis and autoradiography. The results obtained indicate that there are marked differences in protein phosphorylation patterns between the zygote and two‐cell stage and between the morula and blastocyst stage. In addition, there is a compaction‐specific change in the phosphorylation profile of three components of Mr 37,000. This compaction‐specific change takes place during compaction in the eight‐cell embryo; thus, it is the first biochemical change specifically correlated to this important event of early development.
Ultrastructure of the head of ctenomys maulinus spermatozoon with special reference to the nucleus
Authors: Feito R. , Barros Claudio 
Published: February 2005

AbstractThe spermatozoa of the neotropical hystricomorph rodent Ctenomys maulinus have been examined cytochemically and under the transmission electron microscope. The head is flattened dorsoventrally. At the caudal end of the head there is a process oriented parallel to the tail. This process corresponds to a cylindrical extension of the nucleus, which constitutes a unique feature among mammals.
Microdensitometric evaluation of the DNA content, as ploidy parameter, of spermatozoa in the polymorphic chromosomal system of Akodon molinae cabrera (rodentia, cricetidae)
Authors: Redi C. A. , Garagna S. , Merani M. S. , Capanna E. , Bianchi N. O. , Romanini M. G. Manfredi 
Published: February 2005

AbstractThe influence of chromosome variability on the production of euploid spermatozoa was investigated in a suitable biological model, the Akodon molinae system. This consists of individuals whose chromosome constitution is 2n = 42, 2n = 43, or 2n = 44. The only difference between these three karyotypes occurs through a Robertsonian rearrangement combined with two pericentric inversions. Thus, the animals with 2n = 42 (simple homozygotes or SH) have two large metacentric chromosomes number 1; animals with 2n = 43 (heterozygotes or Ht) have a chromosome 1 and two subterminal chromosomes la and lb homologues of the long and short arms of the chromosome 1, respectively; animals with 2n = 44 (double homozygotes or DH) have a pair of la and a pair of lb chromosomes. The gametic euploidy frequency correlated with each chromosome constitution was evaluated on the basis of the DNA content of spermatozoa, which was determined microdensitometrically after the Feulgen reaction, taking into account the site of the spermatozoa along the male genital tract. A comparative assessment of gametic aneuploidy frequency in caput epididymis versus vas deferens demonstrated (1) a falloff in euploid production in passing from the 2n = 42 to the 2n = 44 chromosome forms, alongside a high degree of intragroup variability, and (2) a lower aneuploidy frequency in the vas deferens than in caput epididymis in all the forms considered. These two features, taken together with similar results in the mouse chromosome variability system, suggest that a selection mechanism is operative against aneuploid spermatozoa in the epididymis. This finding is of interest in a wider perspective, since it might turn out to be valid for many mammals.
Timing of human sperm chromosome replication following fertilization of hamster eggs in vitro
Authors: Balkan Wayne , Martin Renée H. 
Published: February 2005

AbstractThe visualization of human male pronuclear chromosomes is possible by utilizing a technique in which human sperm fertilize zona‐free Golden hamster (Mesocricetus auratus) ova in vitro. R banding of these chromosomes can be achieved by adding 20 μg/ml 5‐bromode‐oxyuridine (BrdU), a thymidine analogue, to the culture medium during mid‐to‐late S phase and subsequently staining the chromosomes with 0.1 mg/ml acridine orange. BrdU was added 3.0–10.0 hr postinsemination (hr pi). R bands were obtained when fertilized eggs were transferred into medium containing BrdU between 5.0 and 6.5 hr pi. This indicates that the human (male) pronuclear chromosomes were in mid‐to‐late S phase at these times.
Evaluation of premeiotic activity in the developing rabbit testis using a modified squash technique
Authors: Randolph Margaret , Gondos Bernard 
Published: February 2005

AbstractGerm cells in the developing rabbit testis were studied using a modified squash technique. Preleptotene figures present in the postnatal testis were examined and compared with corresponding stages in ovarian germ cells. The findings indicated differences in the pattern of preleptotene changes in the developing ovary and testis.
22Na+and86Rb+fluxes in spermatozoa and oocytes of arbacia punctulata
Authors: Adeyemo Oyewole , Koide S. S. 
Published: February 2005

AbstractThe fluxes of22Na+and86Rb+in Arbacia sperm and oocytes were studied in order to determine how these cells carry out cation exchange with the sea environment. The uptake of these ions by serum followed a pattern of early rapid influx (initial 0.5 min) and subsequent efflux (1–3 min) followed by a gradual uptake (after 3 min). Neither the uptake nor the efflux of these cations by Arbacia sperm were affected by ouabain, suggesting that influx and efflux of22Na+and86Rb+in Arbacia sperm occur predominantly by passive transport. The22Na+uptake by Arbacia oocytes showed a steady increase after an initial rapid uptake. A slight but significant inhibition of22Na+uptake was observed with ouabain. However,86Rb+uptake by the oocytes reached an early equilibrium and was not affected by ouabain. The uptake of Rb+by Arbacia oocyte is by passive transport while that of Na+is both by passive and active transport.
Fusion of hamster and pig zona‐free eggs stimulated by boar and guinea pig sperm at fertilization in vitro
Authors: Pavlok Antonin , Trávník Pavel , Kopečnčy Václav , Šťastná Jitka 
Published: February 2005

AbstractIn the course of in vitro fertilization of zona‐free hamster and pig eggs by boar and guinea‐pig spermatozoa it was observed that homologous and heterologous eggs fused together, forming cell hybrids between two or more cells. The fusogenic activity was attributed to spermatozoa and this was the hypothesis tested. The fusogenic activity (coinciding with sperm penetration activity) was dependent on the duration of sperm preincubation, which may be regarded as capacitation in vitro. Fusion occurred only after 3 hr of sperm preincubation and a narrow optimum was detected at 4–4.5 hr. Fusion of eggs was also dependent on sperm concentration. A relatively high proportion of fusions was observed at a sperm concentration of 4.0 × 104 per ml and an optimum was attained at a concentration of 5.0 × 105 per ml. The first fusions were observed at 90 min after semination. After 3 hr more than a half of the eggs reacted, and by 20 hr of incubation 80% of ova were fused. The fusability of eggs was tested and found to occur at 14 hr after ovulation. The fusion process was also studied using transmission electron microscopy. It is supposed that the process of egg fusion may be caused either by a similar mechanism to sperm‐egg fusion, or by products released during the sperm acrosome reaction.