bluuebunny/crossref_metadata_2025_split huggingface dataset:
Delayed fertilization of anuran amphibian (Xenopus) eggs leads to reduced numbers of primordial germ cells
Authors: Wakahara Masami , Neff Anton W. , Malacinski George M. 
Published: February 2005

AbstractSeveral media were tested for the extent to which they promoted high fertilization efficiencies in ovulated, stripped Xenopus eggs. One medium was selected for maintaining eggs in a ‘delayed fertilization’ (DelF) condition. DelF eggs displayed several unusual characteristics, including shift of the center of gravity, prominent sperm entrance site, and occasional polyspermy.The frequency of normal pattern formation varied according to the length of time eggs were maintained in the DelF condition. Various developmental abnormalities were observed during gastrulation, neurulation, and organogenesis. Most abnormalities appeared, however, to be related to morphogenesis of the endoderm.Primordial germ cell (PGC) development was examined in DelF eggs which displayed normal external morphological features at the swimming tadpole stage. PGC counts were usually normal in short‐duration (eg, 5 hr) DelF eggs, but frequently substantially reduced or completely diminished in longer‐duration (eg, 25hr) tadpoles. Six spawnings were compared and shown to exhibit considerable variability in fertility, morphogenesis, and PGC development. Yolk platelet shifts and developmental parameters were examined in two additional spawnings.The subcortical cytoplasm in which the germ plasm is normally localized appeared to be disrupted in longer duration DelF eggs. That observation may account for low PGC counts in DelF tadpoles.
Changes at the hamster oocyte surface from the germinal vesicle stage to ovulation
Authors: Ebensperger C. , Barros C. 
Published: February 2005

AbstractImmature and ovulated hamster oocytes were studied with the scanning electron microscope. Immature oocytes at the germinal vesicle stage have their surface uniformly covered by microvilli. When meiosis has progressed to the first meiotic metaphase the overlying surface shows the differentiation of a circular area 19 μm in diameter with a low density of microvilli. Later, from this region the first polar body emerges, and the oocyte surface at the point from which it was extruded shows a cluster of cytoplasmic, conical projections. When the zona‐free oocytes are cultured at 37°C for 5 minutes these projections disappear and the oocyte surface at that point becomes smooth. However, when the oocytes remain in the oviduct for several hours after ovulation these projections remain unchanged. The in vitro interactions of capacitated hamster sperm with the immature oocyte was always seen at microvillus surfaces and never associated with the differentiated regions.
Inactivation of the (+) gamete agglutinin during the mating‐type reaction in chlamydomonas
Authors: Wiese Lutz , Hardcastle Alison , Stewart Mary 
Published: February 2005

AbstractSex cell contact in Chlamydomonas is due to complementary sex‐specific glycoproteins (mating‐type substances, MTSs). Their interaction causes an instantaneous but labile flagella agglutination between sexually different gametes. The dynamic nature of this contact permits partner exchange between agglutinated gametes and accounts for the transitoriness of the contact, flagella adhesion being terminated upon ensuing pairing. This paper describes molecular events that underlie the adhesion potential of differentiated (+) gametes. In the contact‐establishing interaction with its receptors on the (−) flagella, the agglutinin of differentiated (+) gametes is inactivated. Compensating for this inactivation, the adhesion potential of gametes in agglutination is sustained by continuous replenishment of the inactivated MTS by newly synthesized units. If this glycoprotein neosynthesis is blocked by tunicamycin (TUM), the adhesiveness of differentiated (+) gametes ceases. It is postulated that this complex interaction with incapacitation and neosynthesis forms the basis of the dynamic nature of the flagella contact and eventually accounts for its termination at pairing.
The pH dependence of motility and the acrosome reaction of guinea pig spermatozoa
Authors: Murphy Susan J. , Yanagimachi Ryuzo 
Published: February 2005

AbstractThe effect of pH on both motility and the acrosome reaction of guinea pig spermatozoa was examined by transferring fully capacitated spermatozoa from Ca2+ ‐free medium to Ca2+ ‐containing media with various pH values (8.2, 7.5, 7.0, 6.7, 6.4, and 6.1). When transferred to media of pH 7.5 or 8.2, the spermatozoa underwent their acrosome reactions to the maximum level within 15–20 min. Acrosome‐reacted spermatozoa were vigorously motile. The intensity of sperm motility and the incidence of the acrosome reaction declined with decreasing pH values. At pH 6.1, the motility of all the spermatozoa quickly became very weak. No acrosome reactions occurred at this low pH. The inhibition of motility and the acrosome reaction at pH 6.1 was reversed by transferring the spermatozoa back to the alkaline medium unless they were exposed to this low pH for longer than 3 hr. The inhibition of the acrosome reaction at low pH values (other than 6.1) was counteracted to some extent by increased concentrations of Ca2+ (4–10 mM). Possible mechanisms by which low pH reversibly inhibits sperm motility and the acrosome reaction are discussed.
Different environmental stresses can activate the expression of a heat shock gene in rabbit blastocysts
Authors: Heikkila John J. , Schultz Gilbert A. 
Published: February 2005

AbstractWe have utilized the rabbit 6‐day blastocyst as a model system in which to examine the effect of environmental stress on embryonic gene expression. Elevation of the incubation temperature from 37 to 43 °C, exposure to 50 μM sodium arsenite or mechanical injury (resulting in the structural collapse of the 6–day rabbit blastocyst) was found to depress total protein synthesis as well as enhance the synthesis of a 70,000‐dalton stress‐induced protein. The molecular mass of this stress protein is similar to a heat shock protein (HSP) found in other eukaryotic systems. A recombinant DNA probe consisting of the 5′ end of a mouse gene for a 70,000‐dalton HSP hybridized to RNA isolated from heat shocked, sodium arsenite‐treated, and mechanically injured blastocysts but not to RNA isolated from control embryos. These results as well as in vitro translation data suggest that the expression of the 70 K HSP is controlled at the transcriptional level. The levels of actin mRNA, as detected by means of a recombinant DNA probe encoding a Drosophila actin gene, did not undergo a major alteration following these different stresses. The relevance of these observations to embryonic cellular homeostatis is discussed.
Lysosomal hydrolases in reproductive organs during estrous cycle of the hamster
Authors: Rahi Hamid , Srivastava Prakash N. 
Published: February 2005

AbstractChanges in the total protein content and the activities of lysosomal hydrolases (arylsulfatase, acid phosphatases, β‐glucuronidase, β‐N‐acetylhexosaminidase, α‐L‐fucosidase, and β‐galactosidase) of the hamster genital tract during the 4 days of estrous cycle and in hormonally superovulated hamsters were measured. Levels of lysosomal hydrolases in uteri and uterine fluid changed significantly during the cycle. Similar changes were observed in uterine wet weight and uterine proteins. The pattern of enzyme activities in both the ovary and the oviduct were different from those in uteri. In the ovary, most enzyme activities and the total protein concentration remained elevated after ovulation. Protein concentration and enzyme activities were significantly higher in the ovary, oviduct, and uteri of superovulated hamsters as compared to controls.
Developmental capacity of rat embryos produced by in vivo or in vitro fertilization
Authors: Shalgi Ruth 
Published: February 2005

AbstractThis work compares the ability of rat zygotes fertilized in vitro or in vivo to develop into viable embryos. All oocytes were from adult cyclic females. After the first cleavage, the zygotes were transferred to oviducts of pseudopregnant recipients. Their fate was examined on day 13 at laparotomy and again on day 20. Ninety‐five of 146 in vivo fertilized zygotes developed into normal sized 13‐day fetuses and 72 (55%) to apparently normal near‐term fetuses. Forty‐six of 135 in vitro fertilized zygotes developed up to day 13, and 30 (24%) developed to term. It appears that the probability that in vitro fertilized rat zygotes will develop into viable embryos is about half the chance of in vivo fertilized zygotes. Since the two types of zygotes were morphologically identical, the morphological appearance of the two‐cell stage is not an adequate criterion for judging developmental potential.
Effect of anti‐sperm antibody on the in vitro development of rat embryos
Authors: Koyama Koji , Hasegawa Akiko , Isojima Shinzo 
Published: February 2005

AbstractSince we previously proved that the fertilized rat eggs in early developmental stage have antigen(s) cross‐reacting to spermatozoa, the effect of antibody to spermatozoa on the cleavage of fertilized rat eggs was examined in vitro. Fertilized eggs from Fisher rats in the morula stage were cultured in vitro for 15 to 39 hr in the medium containing antibody to rat spermatozoa and rabit complement, and the developmental rates of morulae to blastocysts were compared with those cultured in the presence of either antibody or the complement alone. When rat morulae were cultured in the medium containing rabbit complement and IgG from rabbit antiserum to rat spermatozoa (heteroantibody) or from rat antiserum to rat spermatozoa (isoantibody), the development of moralae to blastocysts was markedly suppressed, whereas those cultured in the medum containing rabbit complement and IgG from the control rabbit serum or rabbit antibody IgG to rat spermatozoa alone without complement normally developed to the blastocysts. These results indicate that the antibody to spermatozoa in presence of complement can impair the in vitro development of fertilized rat eggs.
An improved method to visualize human sperm chromosomes using zona‐free hamster eggs
Authors: Chaudhuri J. P. , Yanagimachi R. 
Published: February 2005

AbstractAn improved method for human sperm chromosome preparation is described. Improvements include (1) the use of a sperm population with high motility and normal morphology for insemination, (2) the insemination and postinsemination culture of zona‐free eggs in Holmes medium, which does not require serum supplementation, (3) control of sperm concentration at insemination to avoid heavy polyspermy, (4) reduction of the occurrence of egg agglutination by placing the medium for postinsemination culture in a ring or crescent shape instead of a droplet, and (5) application of a two‐step fixation method to augment the efficiency of chromosome preparation.
Fish germinal cells. I. Comparative spermatology of seven Cyprinid species
Authors: Baccetti B. , Burrini A. G. , Gibertini G. , Mazzini M. , Zerunian S. 
Published: February 2005

AbstractThe spermatozoa of seven fishes belonging to Cyprinid family are examined. They have no acrosome, like all Teleost fishes, a spheroidal or slightly elliptic nucleus, always eccentrically placed on the tail, two variously oriented centrioles, and a postnuclear cytoplasmic region of various size that contains some mitochondria (2 to 10) and surrounds a periaxonemal postnuclear canal. The tail is of moderate length (from 36 to 60 μm) and contains a “9 + 2” axoneme: both dynein arms are present. Comparative examination of the spermatozoa in the seven species shows that significant differences occur among them, even when they belong to the same genus. These concern the tail length; the position of the centrioles, the proximal with respect to the central one and with respect to the nucleus; the number of mitochondria, which is in relationship to the depth of the postnuclear canal. In the uniform general pattern of the ultrastructure of the Cyprinid spermatozoa, each species is characterized by a particular organization of the sperm organelles; in this respect, the two species examined by us, Leuciscus cephalus and souffia, are more closely related, even if easily recognizable one from the other. From a phylogenetic point of view, the comparative spermatology of the Cyprinid fishes suggests that the mitochondrial number is a good character, which enables us to order them in a phylogenetic arrangement.
Influence of the concentration of sperm on the percentage of eggs fertilized for three strains of mice
Authors: Robl James M. , Dziuk Philip J. 
Published: February 2005

AbstractThis study was conducted to determine the optimal concentration of sperm to use for the insemination of females to detect differences among strains of mice in the percentage of eggs fertilized. Female ICR mice were inseminated with sperm of concentrations ranging from 0.25 to 8 × 106/50 μl from males of either DBA/2N, CF1, or C57BL/6N strains. Differences among strains were detected only when approximately 50% of the eggs were fertilized but not when each of the strains fertilized either a high or low percentage of eggs. The optimal concentration of sperm therefore was the concentration that gave approximately 50% fertilized eggs.
A further study of lysolecithin−mediated acrosome rection of guinea pig spermatozoa
Authors: Yanagimachi Ryuzo , Suzuki Fumie 
Published: February 2005

AbstractWhen guinea pig spermatozoa are preincubated for 1 hr in Ca2+−free medium containing a low concentration of lysolecithin (LC, 85 μg/ml) and then exposed to 2 mM Ca2+ by diluting the preincubation medium with an equal volume of LC−free, 4 mM Ca2+−containing medium, the majority of the spermatozoa undergo acrosome reaction promptly. On the other hand, when the preincubated spermatozoa are exposed to 2 mM Ca2+ without reducing the original concentration of LC in the medium, none of them undergo acrosome reaction. These spermatoza can acrosome−react if they are transferred to an LC−free medium. These results and those of some other experiments suggest that in the presistent presence of a high concentration of LC in the medium, exogenous Ca2+ essential for the acrosome reaction either does not penetrate the sperm plasma membrane or, if it does, it cannot alter the membrane for the acrosome reaction, at least under the experimental conditions employed. Freeze−fracture examination of the sperm plasma membrane has revealed that small areas or patches free of intramembranous paarticles (IMPs) appear in the membrance during sperm preincubation, and these IMP−free areas expand drastically in response to Ca2+ when the LC conccentration in the medium is reduced at the time Ca2+ is added to the medium. In contrast, IMP−free areas remain unchanged even after exposure of spermatozoa to Ca2+ if the concentration of LC remains at its original level of 85 μg/ml.
The influence of postovulatory age on the rate of cleavage in in‐vitro fertilized rat oocytes
Authors: Shalgi R. , Kaplan R. , Kraicer P. F. 
Published: February 2005

AbstractThe purpose of this study was to analyze the effect of postovulatory ‘aging’ in the oviduct on the rate of zygotic development. Two ovulatory ages were tested: oocytes collected from the oviducal ampullae 1) soon after ovulation (denoted freshly ovulated) or 2) 7‐hour postovulation. All the oocytes were from superovulated immature rats. By manipulation of the timing of the ovulatory hormone treatment, it was possible to place both types of oocytes into sperm suspension from the same pool and at the same time. The oocytes and spermatozoa were coincubated overnight. Cleavage was established by interference contrast microscopy. The time of the first cleavage of ova from the 7‐hour postovulation group was clearly advanced. Because the cleavage time curves were not parallel, no reliable estimate of the time difference could be made, but it was clearly in the range of 2 hr. This shift could not be related to any difference in the time of sperm penetration. Both groups of oocytes underwent penetration by spermatozoa at the same time. The time interval between maximal sperm penetration (94% of oocytes in both groups) and maximal cleavage (50% in both groups) was 23 hr in the freshly ovulated and 21 hr in the 7‐hour postovulatory eggs. Nor was the difference related to polyspermy, which was approximately 14% in both groups. These results support the hypothesis that developmental processes are under way in the oocyte before fertilization, but at a much slower rate than after fertilization.
Maturation of pig and rat oocytes transplanted into surrogate pig follicles in vitro
Authors: Fleming Alan D. , Kuehl Thomas J. , Armstrong David T. 
Published: February 2005

AbstractPig oocytes obtained from slaughterhouse material and rat oocytes obtained from PMSG‐treated immature females were incubated as isolated oocytes or injected into explanted pig follicles (5–8 mm). Free oocytes of both species, with or without their cumulus investment or gonadotropins during culture, matured at high rates after 30 hr or 9–10 hr of culture, respectively. Gonadotropic stimulation was necessary for maturation of both the native and injected cumulus‐intact pig oocytes in follicle culture. Cumulus‐free pig oocytes injected into follicle failed to mature in response to gonadotropic stimulation, suggesting an inability to perceive or respond to stimulation. Injected rat oocytes, however, matured irrespective of cumulus investment or gonadotropic stimulation. Their maturation was delayed and reduced at 9 hr. These results in the rat suggest that the pig follicular environment is incapable of regulating rat oocyte maturation but rather presents a permissive or supportive environment for their maturation. The explanted surrogate follicles from the pig or other species may provide a useful model for the study of oocyte‐follicle interactions in oocyte maturation within or between species.
A mouse embryo culture system for quality control testing of human in vitro fertilization and embryo transfer media and fetal cord sera
Authors: Cheung Sau W. , Strickler Ronald C. , Yang Victoria C. , de Vera Michelle , Spitznagal Edward L. 
Published: February 2005

AbstractSwiss white mice were superovulated, mated, and sacrificed to recover two‐cell embryos that were cultured in Ham's F‐10 supplemented with 15% fetal serum. In 16 experiments, media enriched with fetal bovine serum (FBS) supported blastocyst development from 80% ± 19% (mean ± S.D.) of two‐cell embryos. Culture media + FBS was the positive control when 74 batches of heat‐inactivated human fetal cord serum (hFCS) were tested. Statistical analyses indicated two distinct populations: 49 hFCS promoted blastocyst formation and 25 hFCS grew fewer blastocysts. In five studies, 35/47 two‐cell embryos recovered from mice oviducts in media + FBS and immediately incubated formed blastocysts (75% ± 10%). In six comparison studies where the recovered embryos stood at room temperature for 30 minutes before incubation, only 18/57 (29% ± 21%) became blastocysts. When the colony was housed for 1 week in rooms with Shell No Pest Strips as treatment for mites, only 11/125 two‐cell embryos became blastocysts (9%). In contrast, animals housed in quarters decontaminated with chlorine bleach had reduced breeding efficiency and produced fewer two‐cell embryos. We conclude that (1) Ham's F‐10 + FBS is an excellent positive control to test new batches of hFCS; (2) hFCS that supports blastocyst formation from ≥75% of two‐cell embryos is adequate for human use; (3) pesticide treatment of breeding colonies and cooling of murine embryos during harvest both impaired in vitro blastocyst development; and (4) chlorine bleach cleansing of animal quarters reduced the number of successful matings.
Alteration of the human sperm surface during in vitro capacitation as assessed by lectin‐induced agglutination
Authors: Singer Sherry L. , Lambert Hovey , Cross Nicholas L. , Overstreet James W. 
Published: February 2005

AbstractHuman sperm incubated in vitro in BWW medium containing 35 mg/ml human serum albumin acquire the capacity to penetrate the human zona pellucida and to fuse with the zona‐free hamster oocyte. We have studied changes in lectin‐induced agglutination of human sperm during incubation in this medium to detect alterations in the sperm surface which may be correlated with the acquisition of these functions. Sperm incubated for 1, 6, or 24 hr were combined with two‐fold dilutions of lectins for 30 min at 37°C, in 5% CO2, balance air. When pooled data from five donors were analyzed, the average sperm agglutination titer of wheat germ agglutinin (WGA), phytohemagglutinin‐E (PHA), Lens culinaris agglutinin (LCA), peanut agglutinin (PNA), and Pisum sativum agglutinin (PSA) was found to increase significantly (P ≤ 0.06) with incubation in vitro, although there was considerable variation between ejaculates. Ulex europaeus and Dolichos biflorus agglutinins did not agglutinate human sperm (≤250 μg/ml). Results of this screening demonstrate the alteration of sperm surface components during in vitro incubation and suggest that WGA, PHA, LCA, and PSA may prove useful in efforts to correlate changes in the sperm surface with the ability of the sperm to fertilize the egg.
Immunohistochemical localization of the transferrin receptor in the seminiferous epithelium of the rat
Authors: Brown William R. A. 
Published: February 2005

AbstractThe transferrin receptor has been immunohistochemically localized in the seminiferous epithelium of the rat with a monoclonal antibody, MRC OX26, which recognizes the transferrin receptor glycoprotein. The receptor was detectable on mitotically and meiotically dividing germ cells and, less abundantly, on round spermatids. It was lost from germ cells during spermatid elongation and was undetectable on immature spermatozoa. The transferrin receptor was also present on Sertoli cells in the testes of immature animals and on Sertoli cells in the testes of aspermatogenic animals that had been irradiated in utero. It was not detectable on Sertoli cells in the testes of cryptorchid animals. These studies demonstrate that the transferrin receptor is abundant on dividing germ cells as well as dividing somatic cells.
An examination of the method of sizing the spermatozoa of the domestic fowl and duck with an electronic counter
Authors: Hashimoto H. , Terada T. , Tsutsumi Y. 
Published: February 2005

AbstractAlthough many estimations have been made electronically of mammalian sperm volume, detailed investigations have not been reported for avian spermatozoa with an electronic counter. In the present study, sizing of spermatozoa of fowls and Muscovy and Pekin drakes was examined using a Coulter counter (model ZB). In our preliminary work on fowl sperm volumes, we found mono‐ or di‐morphic distribution displays that were modified depending on the combination of amplification (AMP) and aperture current (APC). Therefore, methodology to estimate the fowl and drake sperm volume was examined. Dilution of semen had no effect on the dimorphic distribution pattern of the sperm volume. Density‐gradient centrifugation did not separate two kind of particles in the semen in either continuous or discontinuous Percoll gradients; therefore, we varied settings of AMP and APC, and found that the most suitable settings for measuring sperm volumes of these birds are 1 for AMP and 8 for APC. With these settings, mean volumes of spermatozoa were 5.1 μm3 for fowls, 5.7 μm3 for Muscovy drakes, and 5.6 μm3 for Pekin drakes.