bluuebunny/crossref_metadata_2025_split huggingface dataset:
Architecture of the hamster oocyte‐cumulus complex
Authors: Talbot P. , DiCarlantonio G. 
Published: February 2005

AbstractThe structure of the hamster oocyte‐cumulus complex (OCC) has been analyzed to help understand how mammalian sperm penetrate the investing coats of the oocyte. At ovulation, oocytes of most mammalian species are surrounded by a zona pellucida, corona radiata, and cumulus layer. Cells of the cumulus and corona radiata are separated by an extracellular matrix (ECM) that contains hyaluronic acid. In hamsters, the diameter of mature follicular OCCs is 0.61 ± 0.12 mm, whereas in freshly ovulated OCCs in culture medium it is 0.78 ± 0.15 mm. This indicates the OCC expands at or after ovulation. The corona radiata is 1–4 cell layers deep, and corona radiata cells are closely packed (center‐to‐center distances between adjacent cells in follicular OCCs averaged 14 ± 3 μm). The cumulus layer is 5–8 cell layers deep, and intercellular spaces are much larger (center‐to‐center distances between adjacent cumulus cells in follicular OCCs averaged 50 ± 20 μm). An ovulated OCC has an approximate volume of 248 × 106 μm3 and was estimated to contain approximately 5,700 cells. Studies with stretched OCCs show that ink particles can readily penetrate the extracellular spaces of the cumulus and corona radiata layers and interact with the ECM, staining it black. At the periphery of the OCC, the ECM appeared discontinuous and formed “cords” containing cumulus cells, whereas closer to the corona radiata the matrix completely filled intercellular spaces. Ink penetrated the corona radiata, but the ECM was difficult to visualize because of the close packing of cells in this layer. Our observations on unfixed OCCs show that cell packing becomes more dense proceeding from the periphery of the OCC to the zona pellucida and that the ECM at the periphery differs from the matrix deeper in the OCC. These data suggest that an incoming sperm would find penetration of the investing coats to increase in difficulty (that is physical resistance would increase) as it got closer to the oocyte. We have also examined the effects of processing for microscopy on the structure of the OCC. Both standard fixation procedures and fixation in the presence of ruthenium red caused condensation of the ECM, especially in the cumulus layer, and thus produced a significant decrease in the diameter of the OCC.
Induction of the acrosome reaction in the spermatozoa of the goat by secretions of the male accessory glands and milk
Authors: Courtens J. L. , Nunes J. F. , Corteel J. M. 
Published: February 2005

AbstractThe balancing effects of bulbourethral gland secretion (BUS) and of seminal vesicle secretion (SVS) on goat semen quality were previously demonstrated. In the present study, electron microscope observations revealed a high frequency of spermatozoa with a reacted acrosome among spermatozoa from cauda epididymis exposed to BUS in the presence of milk. This frequency was significantly reduced when SVS had been added either before or after BUS. No reacted acrosome was observed in the absence of milk. All mount spermatozoa were incubated with milk or SVS or BUS or combinations of the three materials labeled with colloidal gold. SVS attached specifically on the plasma membrane covering the anterior part of the acrosome, whereas BUS spread all over the sperm head. Milk attached on the anterior half of the sperm head only when BUS was present in the sperm environment. It is concluded that BUS plays an active role in the induction of the acrosome reaction in the presence of milk and that SVS counteracts this role.
Evidence of phospholipase A2 in the sea urchin egg: Its possible involvement in the cortical granule reaction
Authors: Ferguson James E. , Shen Sheldon S. 
Published: February 2005

AbstractFertilization of the sea urchin egg involves an exocytotic event known as the cortical granule reaction (CGR). In many cell systems, phospholipase A2 is implicated in regulation of the secretory event. Indirect evidence suggests that phospholipase A2 mediates the CGR; however, there has been no direct demonstration of phospholipase A2 activity in the sea urchin egg. We report here evidence of phospholipase A2 activity in egg homogenate of the sea urchin Lytechinus pictus. The enzyme was calcium‐dependent and had a pH optimum near the intracellular pH of the unfertilized egg. Neither exogenous calmodulin nor trifluoperazine had any apparent effect on enzyme activity. Quinacrine, a phospholipase A2 inhibitor, blocked the enzyme activity in the egg homogenate. In intact eggs, quinacrine blocked the CGR in a dose‐dependent, egg‐concentration‐dependent manner. The inhibitory effect of quinacrine on the CGR could not be overcome by the phospholipase A2 activator melittin or by the calcium ionophore A23187. Quinacrine did not inhibit sperm‐egg binding or sperm incorporation. These results lend further support to the hypothesis that phospholipase A2 is involved in the CGR.
Fertilization in a Crab. III. Cytodifferentiation of vesicles enclosing ring‐shaped elements involved in the cortical reaction
Authors: Goudeau Marie 
Published: February 2005

AbstractDuring the cortical reaction, Carcinus maenas eggs successively released a fine granular material and a massive amount of ring‐shaped elements that subsequently formed most of the fertilization envelope. The ring‐shaped elements came from egg cortical vesicles and, owing to their striking morphology, acted as naturally occurring markers in ultrathin sections, which permitted us to understand the pathway of their intracellular transport. In this respect it was established that the ring‐shaped elements and their enclosing vesicles originated in the endoplasmic reticulum both in ripe oocytes and early fertilized eggs maintained under in vitro conditions. The intracellular transport pathway of the endoplasmic reticulum‐derived vesicles seemed to bypass the Golgi apparatus. Accordingly, the ring‐shaped elements appeared to be released by direct exocytosis from the endoplasmic reticulum system.Finally, a tentative scheme of oocytes functioning is suggested for crustacean decapods, based on the remarkable similarities between the structure and ER origin of the ring‐shaped elements involved in the cortical reaction and the disc‐shaped granules traditionally considered as endogenous yolk precursors. The scheme implies that the oocyte ER system might produce a precursor common to the cortical reaction exudate and to the endogenous yolk, in the form of the ring‐ or disc‐shaped elements.
The karyotype and ultrastructural characteristics of spontaneous preimplantation mouse parthenotes
Authors: Anderson Everett , Hoppe Peter C. , Lee Gloria S. 
Published: February 2005

AbstractKaryotypic and light and electron microscopical analyses were made of spontaneous preimplantation mouse parthenotes from the LT/Sv inbred strain. It was found that the activated oocyte and developing embryos were diploid. We believe that diploidization is achieved by the oogonium undergoing a premeiotic mitosis without cytokinesis followed by two meiotic divisions, thus producing diploid parthenotes.The developmental events with respect to membrane specialization, such as junctional complexes, were similar to those observed in fertilized embryos.A unique feature of the developing parthenote was the failure of the mitochondria to change during the morula stage. The mitochondria retained a few irregularly oriented cristae rather than many transversely oriented ones observed in morulae developing from fertilized eggs. The significance of this observation is discussed.
The interactions between spermatozoa and uterine epithelium in the hibernating bat, pipistrellus kuhli natt
Authors: Andreuccetti Piero , Angelini Francesco , Taddei Carlo 
Published: February 2005

AbstractIn hibernating females of Pipistrellus kuhli, as well as in other bats previously described, the spermatozoa inseminated in autumn are stored in the uterus, both free and attached by their heads to the uterine epithelium, throughout winter.With the electron microscope the apical region of the attached sperm heads appears to be contained in plicae of the endometrial cells. Furthermore, a great number of microvilli protruding from the uterine epithelium participate in the interaction with spermatozoa. In the region of contact between the two cell types, their plasma membranes run parallel with a constant 12‐nm gap. The sensitivity of these interactions to EDTA and hyaluronidase suggests an involvement of Ca++ and proteoglycans in these bindings, while their insensitivity to trypsin tends to exclude a role of proteins.In addition, evidence of exocytosis of dense granules just at the bottom of the plicae containing the spermatozoon suggests a transfer of material from the uterine epithelium to the intercellular space, thus supporting a physiological role of these interactions.
The effect of anoxia on fowl spermatozoa: Recovery of fertilizing ability, motility, and cellular concentrations of potassium and ATP
Authors: Wishart G. J. 
Published: February 2005

AbstractFowl semen when diluted in a glutamate‐based medium without glucose, gradually lost its fertilizing ability during 4 hr of anaerobic incubation at 30°C. This incubation regime offered a system by which various in‐vitro tests of spermatozoal viability could be assessed for their usefulness as monitors of fertilizing ability. Widely used tests such as spermatozoal enzyme leakage, dye exclusion, and morphology as assessed by light microscopy showed no change in spermatozoal status as the fertilizing ability declined. However the ability of sperm, during a short aerobic incubation to restore their motility and ATP and K+ concentrations, declined as did their fertilizing ability. When glucose was added to this re‐aeration medium, spermatozoal motility, K+ and ATP concentrations, and fertilizing ability were restored to optimal levels. Thus the fertilizing ability of fowl sperm, following anaerobic storage at 30°C, appeared to be related to their ability to restore ATP and K+ concentrations and motility. An initial event in the loss of fertilizing ability was a loss in the ability of sperm to oxidise endogenous substrates. This could be restored by the addition of glucose.
Rat eggs normally exhibit a variety of surface phenomena during fertilization
Authors: Battaglia D. E. , Gaddum‐Rosse P. 
Published: February 2005

AbstractThe surface topography of the rat egg was examined during fertilization in vitro and in vivo. Using phase optics, 348 in vitro fertilized and 50 in vivo fertilized eggs were continuously monitored throughout the 7‐hour period of sperm incorporation. A myriad of different surface configurations were seen, with each egg exhibiting one or more of the following changes. A small number of eggs (4–6%) formed surface elevations over the sperm head after its detachment from the flagellum, 15–30 min after sperm‐egg fusion; 1 to 1.5 hr after fusion, 40–50% of the eggs produced the so‐called incorporation cone, a prominent surface elevation over the decondensing sperm nucleus. The vast majority of eggs (74–82%) formed surface elevations over the proximal tip of the flagellum 2–3 hr after sperm‐egg fusion. These had no association with the decondensing sperm nucleus. A few eggs (11–12%) exhibited multiple protrusions that were distributed randomly about the egg surface, whereas 14–20% did not manifest any surface elevations and remained spherical throughout the sperm incorporation period. Regardless of the type of surface change, all of the eggs resumed a spherical shape by the time sperm incorporation was complete. These observations are in contrast to the conclusions by previous authors that formation of the so‐called incorporation cone over the decondensing sperm nucleus is a ubiquitous event.
The transport of morphologically abnormal sperm in the female reproductive tract of mice
Authors: Nestor Anne , Handel Mary Ann 
Published: February 2005

AbstractMice of the PL/J strain exhibit a high percentage of morphologically abnormal sperm and provide a model for studying the function of abnormal sperm. The ability of such sperm to reach the site of fertilization within the female reproductive tract has been investigated. We have found a decrease in the percentage of structurally abnormal sperm within the population that reaches the oviduct. This observation suggests either that there is an active selection against abnormal sperm or that they are physiologically disadvantaged in reaching the site of fertilization.
Possible involvement of a sialylated component of the sperm plasma membrane in sperm‐zona interaction in the mouse
Authors: Lambert Hovey , Van Le Anh 
Published: February 2005

AbstractWe have studied the molecular mechanisms of gamete interaction in vitro in the laboratory mouse, Mus musculus. In particular, we were interested in whether this interaction is similar to a lectin‐hapten‐mediated process. Inhibition of sperm‐zona binding was examined using various concentrations (.25 mM to 50 mM) of different sugars (sialic acid α‐methylmannose, glucose, fucose, galactose, and N‐acetyl‐glucosamine). Sperm‐zona binding was significantly decreased when eggs were pretreated with 10 mM of sialic acid or α‐methylmannose but not by other sugars tested. Furthermore, treatment of capacitated sperm with neuraminidase destroyed their ability to bind and fertilize eggs. We have also used a specific lectin for sialic acid from the horseshoe crab (Limulus polyphemus) to agglutinate mouse sperm. The lectin (.120 ng/ml) mediated agglutination of mouse sperm (105 sperm/ml) was routinely observed to increase from a 10% agglutination immediately following their isolation from the epididymis to 100% agglutination 90 minutes later. Collectively, these results suggest the appearance of specific sugar moieties on the surface of the sperm plasma membrane which, in this particular species of mouse, are sialylated glycoproteins acting as ligands for specific receptors on the surface of the egg. These are the first data to indicate that sperm‐egg recognition and attachment is a lectin‐hapten‐mediated process in the mouse.
Improved survival of zygotes in superovulated rats following surgical or pharmacological block of ovarian steroid secretion
Authors: Sherman D. , Shinnar Nili , Lelyveld Y. , Kraicer P. F. 
Published: February 2005

AbstractThe purpose of this study was to test the hypothesis that the preimplantation losses of zygotes in pregnant superovulated juvenile rats was due to an imbalance of ovarian hormones. Twenty‐seven or twenty‐eight‐day‐old rats were injected with 20 iu of PMSG, 25 iu of hCG 50 hr later and mated overnight. From a mean ovulation rate of 52 ± 2 only 16 ± 4 zygotes survived after 4 days. After ligation of the cervical ends of the uteri on the day following fertilization the mean yield of zygotes was 22 ± 6. Ovariectomy on the day of fertilization increased the yield of zygotes to 39 ± 6, but the recovery of the zygotes was seriously complicated by postoperative adhesions and deformations of the adnexa. Inhibition of steroidogenesis with aminogluthehimide phosphate also increased the yield of zygotes. The optimal dose was 45 mg in six divided doses over 3 days, which gave a mean recovery of 57 ± 3 zygotes (of which 75% were blastocysts), that is 100% salvage. A lower dose (30 mg) reduced the recovery to the level of untreated animals, while increasing it to 60 mg resulted in maternal mortality and morbidity, as well as in developmental retardation of zygotes.
Entry of immotile spermatozoa into zona‐free hamster ova
Authors: Williamson Roger A. , Koehler James K. , Smith W. Dianne , Karp Laurence E. 
Published: February 2005

AbstractWe studied six men whose spermatozoa were immotile and possessed a variety of sperm tail structural abnormalities by electron microscopy. The semen of all six subjects had a normal percentage of oval forms and sperm undergoing capacitation and acrosome reaction. Despite the absence of motility, when incubated sperm from these subjects was added to a microdrop of medium containing zona pellucida‐free hamster ova, sperm penetration or entry into the cytoplasm of from 1–9% of the eggs was evident with phase contrast microscopy. This latter finding suggests that, at least in this system, oocytes actively facilitate sperm incorporation. Penetration was absent when sperm of fertile men were rendered immotile, though still viable, by heat treatment.
Fertilization in crabs: IV. The fertilization potential consists of a sustained egg membrane hyperpolarization
Authors: Goudeau Henri , Goudeau Marie 
Published: February 2005

AbstractThe electrophysiological properties of immature and mature oocytes of two crabs were analyzed. Growing immature oocytes of Carcinus maenas and fully grown immature oocytes of Maia squinado had essentially K+ dependent resting potentials, Em, of −61 ∓ 1 mV, n=19, and −67.3 ± 0.5 mV, n=68, respectively. Fully grown immature oocytes of Carcinus maenas showed an Em of −40 ± 1.5 mV, n=19, that was k+ and Cl− dependent. In mature oocytes of both species, the plasma membrane became exclusively permeable to cl− and the Em attained–41 ± 1 mV, n=49 and −34 ± 1.5 mV, n=27 for Carcinus maenas and Maia squinado, respectively. After in vitro insemination, a dramatic increase in egg membrane permeability to K+ was observed. This instantaneously caused a sustained hyperpolarization constituting, for these crabs, the fertilization potential. We observed that concurrently with this electrical response to fertilization, sperm reinitiated the oocyte meiotic maturation previously arrested at the first metaphase. The triggering mechanism of the fertilization potential as well as the possible occurrence of a physiological polyspermy are discussed.
Acrosomal reaction and early events at fertilization in Marthasterias glacialis (Echinodermata: Asteroidea)
Authors: Sousa Mário , Azevedo Carlos 
Published: February 2005

AbstractWhen the spermatozoon of M glacialis contacts the mature oocyte jelly it adheres to it. Following this, there is a slight tumefaction of the acrosome, which is followed by the disruption of the apical acrosomal vesicle and cytoplasmic membranes. Acrosomal vesicle contents are liberated and spread along the outer surface of the oocyte jelly. Meanwhile, the acrosomal process begins to extend, penetrates all the jelly extension, then the vitelline layer, and finally contacts the cytoplasmic egg membrane. Nevertheless, the sperm cell continues lying at the outer border of the jelly. From the beginning of the acrosome reaction the dense and finely fibrillar subacrosomal material is connected, by some expansions, to the basal acrosomal vesicle membrane. Both nuclear and mitochondrial diameters have diminished.
Inhibitors of glycoprotein biosynthesis block fertilization in the hamster
Authors: Ahuja Kamal K. 
Published: February 2005

AbstractThe nature and control of changes in surface carbohydrates in capacitating hamster spermatozoa were analysed by using five inhibitors of glycoprotein biosynthesis in an in vitro fertilization system. Epididymal spermatozoa were treated with amphomycin, bacitracin, tunicamycin, 2‐deoxyglucose, and 2‐deoxy‐2‐fluoro‐D‐glucose either during the entire period of capacitation or briefly at the end of capacitation before exposing to Con A‐coated agarose beads or hamster eggs with or without their zonae pellucidae. Untreated 4½‐5‐hr spermatozoa exhibited nearly 100% fertilization and became bound to Con A‐agarose beads mainly along the length of their flagellae, resulting in the formation of clumps on the beads. In the presence of inhibitors of glycosylation, spermatozoa did not bind to Con A‐agarose beads or zona‐intact oocytes and they did not fuse with the zona‐free oocytes. Sperm‐zona binding was also inhibited by UDP‐galactose and UDP‐N‐acetylglucosamine, but not by UDP‐glucose. Sperm motility was not damaged by these inhibitors, and zona‐intact and zona‐free oocytes pretreated with these inhibitors underwent normal fertilization with untreated spermatozoa. These results further strengthen the view that glycoproteins on the sperm surface may be required during different stages of fertilization, including sperm‐egg fusion.
Studies on the stability of 125I‐purified porcine zona antigen (PPZA) obtained by chloramine‐T glucose oxidase with lactoperoxidase and N‐bromosuccinimide lodination procedures
Authors: Subramanian Marappa G. , Yurewicz Edward C. , Sacco Anthony G. 
Published: February 2005

AbstractA purified pig zona antigen (PPZA) was labeled with 125I by chloramine‐T (CL‐T), glucose oxidase with lactoperoxidase (GO‐LP), and N‐bromosuccinimide (N‐BS) iodination procedures. The 125I‐PPZA fractions thus obtained were reconstituted to a concentration of 25,000 dpm/0.1 ml and tested at weekly intervals for binding capacity to a fixed dilution (1:400,000) of PPZA antibody. The 125I‐PPZA obtained by the N‐BS procedure showed greater stability compared to that obtained by CL‐T and GO‐LP methods. The nonspecific binding levels for the N‐BS and GO‐LP methods were comparable and significantly lower than for the CL‐T method.
Dispersion of the cumulus oophorus and dissolution of the zona pellucida in oocytes of DDK and other strains of mice
Authors: Wabik‐Sliz Barbara 
Published: February 2005

AbstractThe time needed in vitro for granulosa cell dispersal with hyaluronidase and for lysis of the zona pellucida with α‐chymotrypsin was estimated for unfertilized eggs from three inbred strains of mice, DDK, C57BL, and C3H, and one outbred strain, Q. Granulosa cells were dispersed most rapidly in the DDK and most slowly in the C3H strain.The time needed for dissolution of the zona pellucida was also shortest for DDK eggs and longest for C3H eggs. The results suggest that the high sensitivity to enzymes of the granulosa layer and the zona pellucida of DDK eggs may allow more than one spermatozoon to penetrate through these barriers before the block against polyspermy is completed. The percentage of unfertilized eggs containing spermatozoa under the zona pellucida on the day of copulation was abnormally high in matings of females from the DDK inbred strain with males from DDK and C57BL strains. This may suggest some disturbances in establishing contact between the egg plasma membrane and fertilizing spermatozoa.
Separation of mouse testis cells on a Celsep™ apparatus and their usefulness as a source of high molecular weight DNA or RNA
Authors: Wolgemuth Debra J. , Gizang‐Ginsberg Elena , Engelmyer Eric , Gavin Brian J. , Ponzetto Carola 
Published: February 2005

AbstractThe use of a self‐contained unit‐gravity cell separation apparatus for separation of populations of mouse testicular cells is described. The apparatus, a Celsep™, maximizes the unit area over which sedimentation occurs, reduces the amount of separation medium employed, and is quite reproducible. Cells thus isolated have been good sources for isolation of DNA, and notably, high molecular weight RNA.