bluuebunny/crossref_metadata_2025_split huggingface dataset:
Susceptibility of epididymal boar sperm to cold shock and protective action of phosphatidylcholine
Authors: Simpson A. M. , Swan M. A. , White I. G. 
Published: February 2005

AbstractRapidly cooling (cold shocking) washed cauda boar sperm irreversibly reduced motility and respiration and greatly increased the uptake of 45Ca2+; the plasma membranes were removed and the acrosomes detached from nuclei. The motility, respiration, and calcium uptake of the less mature caput sperm were largely unaffected; and there was little damage to the ultrastructure. This indicates that boar sperm becomes less resistant to cold shock as they mature in the epididymis.The oxygen uptake, glucose breakdown, and lactic acid production of control caput sperm was less than that of cauda sperm. This suggest that the maturation of sperm in the epididymis of the boar involves an increase in both the glycolytic and oxidative phases of glucose metabolism.The presence of 2.0 mg/ml phosphatidylcholine (lecithin) in the medium prevented ultrastructural damage to cauda sperm on cold shock, and motility and respiration were maintained at levels similar to those of control sperm. Although the presence of phospholipid reduced the large calcium influx following cold shock, it was still greater that that of control sperm.The “protective” effect against cold shock was not maintained after rewashing the sperm free of phosphatidylcholine prior to cold shock, indicating a fairly “loose” interaction of the phospholipid with boar sperm membranes that was easily disrupted.
Sperm‐sperm associations in the loris epididymis
Authors: Phillips David M. , Bedford J. Michael 
Published: February 2005

AbstractIn a few mammals, the passage of maturing spermatozoa through the epididymis is characterized by development of persistent associations between one or more neighboring cells over the acrosomal region. The converse situation is described here in the loris, Nycticebus coucang, a prosimian primate. Loris spermatozoa released at spermiation enter the caput epididymidis as single cells and then become stacked in rouleaux of 2–8 spermatozoa there, the peri‐acrosomal plasmalemma of one being linked by a unique junctional complex to that of its neighbor. However, by the time the cauda is reached, all the spermatozoa have separated again to lie as single cells, which now display major aggregations of ordered material over the concave surface of the acrosome. The functional significance of these unusual sperm surface‐related phenomena in the loris epididymis is not clear.
Cytogenetic technique for mouse metaphase II oocytes
Authors: Mailhes John B. , Yuan Zhi Ping 
Published: February 2005

AbstractThe acquisition of cytogenetic data from mammalian oocytes has required considerable time and expense, since only a relatively small number of oocytes could be processed from three to four animals daily. The availability of a procedure that would facilitate fixation and preparation of air‐dried slides from 25–30 superovulated mice within a 3‐h period would enhance development of germ cell cytogenetic data by reducing technician time and animal maintenance expense. We present such a procedure for mouse metaphase II oocytes. Mice were superovulated and the oocytes collected were fixed en masse prior to making air‐dried slides. Chromosomes were subsequently C‐banded to enhance objective cytogenetic analysis. The reliability of the procedure was determined by harvesting 44,814 oocytes from 1,875 mice over a 9‐month period and calculating the proportion of cells cytogenetically analyzed to those not analyzed. Cytogenetic analysis of oocytes is an assay for chemicals (and other agents) capable of inducing numerical and structural chromosomal aberrations.
Ultrastructure of in vivo fertilization in the goat
Authors: Crozet N. , Théron M. C. , Chemineau P. 
Published: February 2005

AbstractIn vivo fertilization of goat eggs has been studied by electron microscopy. Eggs were recovered from superovulated or natural cyclic goats, 32 to 52 hours after the onset of oestrus; only eggs recovered between 46 and 52 hours were fertilized.Spermatozoa penetrated the zona pellucida tangentially leaving vesiculated products of the acrosome reaction at the zona surface.As sperm penetrated into the ooplasm, the second meiotic division completed and cortical granule exocytosis occurred. However a few unreacted cortical granules usually remained in the cortex of the two fertilized eggs, adjacent to the plasma membrane.After swelling the two pronuclei presented similar ultrastructural morphology: they contained small, compact, agranular nucleoli and unevenly distributed chromatin. The cytoplasm in close vicinity to the apposed pronuclei contained large stacks of annulate lamellae, smooth endoplasmic reticulum, prominent Golgi complexes, as well as dense areas of unidentified material. The abundance of cytoplasmic organelles near the pronuclei might be the expression of intensive metabolic activity. Conversely, in the cortex of fertilized ova several large organelles‐free cytoplasmic areas were randomly distributed.
Development of the nucleolus in early goat embryos
Authors: Chartrain I. , Niar A. , King W. A. , Picard L. , St‐Pierre H. 
Published: February 2005

AbstractIn vivo nucleologenesis was studied in goat embryos from the pronuclear stage to the blastocyst stage by light and electron microscopy. Ultrastructural changes of the nucleoli were characterized by the following progression: homogeneous electron‐dense fibrillar primary nucleoli in the pronucleus; small, dense fibrillar masses dispersed in clusters of chromatin at the two‐cell stage; ring‐shaped nucleoli made up of a fibrillar center surrounded by a layer of dense fibrillar components at the four‐cell stage; reticulated nucleoli composed of a three‐dimensional network of fibrillar components surrounded by small amounts of granular components at the eight‐cell stage; fully developed compact‐type nucleoli consisting of several fibrillar centers each surrounded by a layer of fibrillar componenets and abundant granular components in morulae and blastocysts. Moreover, it was concluded that activation of rRNA transcription, as evidenced by specific silver nitrate staining of the nucleolus organizer regions of metaphase chromosomes, occurs at the two‐to four‐cell stage and that the morphological changes accompanied a substantial increase in nucleolar transcriptional activity up to the blastocyst stage. This study provides evidence that a structure‐function relationship exists during nucleologenesis in goat embryos.
Mechanism of egg attachment stalk formation in the lobster, Homarus
Authors: Goudeau M. , Talbot P. , Harper R. 
Published: February 2005

AbstractWe have examined the formation of the egg attachment stalk in the lobsters Homarus americanus and H. gammarus. The formation of the stalk is similar in both species. Ovulated oocytes are surrounded by a single coat, envelope 1, composed of layers 1A and 1B. After passage through the gonopore and exposure to sea water, envelope 1 swells and becomes sticky. A second coat, envelope 2, forms between the oocyte and envelope 1 during a complex cortical reaction initiated after fertilization. Eggs pass over the ventral surface of spawning females to the region of the pleopods, where they stick by means of layer 1A to each other and to the ovigerous setae. Layers 1A and 1B are soft and pliable at this time. During egg attachment, the pleopods beat vigorously and cause envelope 1 to stretch and form attachment stalks. Beating probably also causes the attachment stalks to twist and wrap around the ovigerous setae. After the egg mass is secured to the ovigerous setae, envelope 1 of both the attachment stalk and egg coat condenses to form a tough material capable of securing the egg mass to the pleopods for intervals up to 16 months. After larvae hatch, portions of the egg coats and the attachment stalks are retained on the ovigerous setae until the female undergoes her next molt.
Ultrastructure of the spermatozoon of Lepidogalaxias salamandroides and its phylogenetic significance
Authors: Leung Luke K.‐P. 
Published: February 2005

AbstractThe spermatozoon of Lepidogalaxias salamandroides possesses an acrosome (putative), one or two perforatoria (putative) but no nine‐triplet centrioles. Two elongated mitochondria (12 μm long) are situated in parallel between the nucleus (20 μm long) and the axoneme (53 μm long). The above features are unique among other teleosts with internal fertilization. The presence of an “acrosome” in this primitive teleost supports the hypothesis that this structure has been secondarily lost in teleosts during evolution. The uncertainty of phylogenetic placement of this fish is reflected by its unique sperm ultrastructure.
Morphological observations on sperm–egg interactions during in vivo fertilization in the dasyurid marsupial Sminthopsis crassicaudata
Authors: Breed W. G. , Leigh C. M. 
Published: February 2005

AbstractThe aim of the present study was to determine the morphological changes that take place in the male and female gametes during in vivo fertilization in the Australian marsupial, the fat‐tailed dunnart, Sminthopsis crassicaudata. Plastic sections were cut of sperm and eggs recovered from the oviducts of recently mated individuals, and light microscopy of thick, and transmission EM of thin, sections was carried out. It was found that, before penetration of the zona, the spermatozoon came to lie along the outer surface with its rostral tip forming a depression in the zona substance. During penetration, zona material was packed tightly around the spermatozoon, and no large hole was formed. A spermatozoon within the perivitelline space had made contact with the oolemma by way of its apical tip. In a spermatozoon partly incorporated into the ooplasm, fusion appeared to have taken place between its plasma membrane and that of the oolemma. Mucoid coat material became deposited outside the zona at this time; its existence and/or the release of cortical granule content probably prevented polyspermy. Once inside the egg cytoplasm, the sperm head sometimes travelled a considerable distance before chromatin decondensation occurred. In addition, it appeared to rotate somewhat on its axis at this time. Finally, some membranous structures were found around two condensed sperm heads in the ooplasm, which may have been part of the pronuclear envelope. Thus this study on in vivo fertilization in the dunnart documents, for the first time, some aspects of fertilization in an Australian marsupial as seen with the transmission electron microscope; it indicates a few differences from those previously found for the American opossum.
Sperm head structure of a murid rodent from Southern Africa: The red veld rat Aethomys chrysophilus
Authors: Breed W. G. , Cox G. A. , Leigh C. M. , Hawkins P. 
Published: February 2005

AbstractThe morphology of spermatozoa from the red veld rat, Aethomys chrysophilus, of Southern Africa is described; two very different types were found, which came from animals from two separate, as‐yet‐undescribed, species. In individuals from South Africa the sperm head had a somewhat disc‐shaped nucleus and a large acrosome with a huge apical segment that, during epididymal transit, changed in form from initially projecting anteriorly to a highly complex structure that was flexed caudad and lay alongside part of the rest of the sperm head. In addition, the chromatin generally appeared to be not fully condensed. Spermatozoa from animals collected in Malawi were very different in morphology and had a head with a typical apical hook, a perforatorium, fully condensed chromatin, and a 4‐μm‐long ventral spur. Its sperm tail was also significantly longer. The time of divergence of these two groups of animals from a common ancestor is not known, but the present results show that a considerable morphological change in the sperm nucleus, acrosome, and subacrosomal space can evolve even between two, presumably closely related, species.
Development of hamster two‐cell embryos in the isolated mouse oviduct in organ culture system
Authors: Minami N. , Bavister B. D. , Iritani A. 
Published: February 2005

AbstractHamster early two‐cell embryos developed to the expanded blastocyst stage within the isolated mouse ampulla maintained in organ culture system. Mouse ampullae isolated at different times after treating the mice with human chorionic gonadotropin (hCG) (0–72 h) or pregnant mare's serum gonadotropin (PMSG) (30–32 h) were flushed with culture medium, and hamster early two‐cell embryos were introduced into these ampullae. Mouse ampullae isolated at 14–32 h after hCG injection were more favorable for the development of the embryos than those isolated at 70–72 h. When mouse ampullae were isolated 30–32 h after hCG or PMSG treatment, 39% of the cultured eggs developed, some of them to the expanded blastocyst stage after additional culture for 65–70 h. These results indicate that unknown oviductal factors stimulate the development of hamster early two‐cell embryos, and these factors are under the control of hCG or PMSG. In addition, these factors are common to the mouse and hamster.
Effect of defolliculation and 17α‐hydroxy, 20β‐dihydroprogesterone on cyclic AMP level in full‐grown oocytes of the rainbow trout, Salmo gairdneri
Authors: Finet B. , Jalabert B. , Garg S. K. 
Published: February 2005

AbstractThe changes in cAMP were followed in trout oocytes incubated in vitro after defolliculation performed by either enzymatic or manual dissection. Both defolliculation methods induced a highly significant rise in oocyte cAMP level (4.5 times the basal level of control [follicle‐enclosed oocytes], after 6 h). Treatment of defolliculated oocytes with 17α‐hydroxy,20β‐dihydroprogesterone (17α,20β‐OH‐P) (10−6 M), which induced oocyte maturation (germinal vesicle breakdown [GVBD]) was able, first, to interrupt the increase of oocyte cAMP level promoted by defolliculation and then to lower this level significantly down to values that still remained higher than folliculated controls. Very low concentrations of 17α,20β‐OH‐P (1.38–55.6 10−9 M), or physiological doses of testosterone (0.35 10−6 M, in the range found in vivo before ovulation) were able to induce a similar decrease of oocyte cAMP level without inducing GVBD. Under the same experimental conditions estradiol (0.35 10−6 M) exhibited no action. These results suggest that some factor(s) originating in the follicle (FIF), inhibit the oocytes' tendency to accumulate cAMP before the final surge of 17α,20β‐OH‐P. This factor might be a follicular steroid such as testosterone or nonmaturing concentrations of 17α,20β‐OH‐P. Moreover our data favour the hypothesis that the final surge of 17α,20β‐OH‐P could induce distinct intraoocyte mechanisms: the first induces an irreversible blockage of cAMP level before the inhibitory action of the FIF is suppressed by ovulation, and the second mechanism leads to GVBD.
Fine structure of sheep fertilization in vitro
Authors: Crozet N. 
Published: February 2005

AbstractThe fertilization events of the sheep oocyte have been investigated by electron microscopy. Thirty‐two oocytes recovered from the oviducts of superovulated ewes were fertilized in vitro by a procedure that has given rise to full embryonic development (Crozet et al.: Gamete Res 16:159–170, 1987) and were analyzed at different stages of fertilization.Sperm incorporation in the ooplasm occurred as early as 2 h postinsemination (PI). One hour later, a fertilization cone containing very few cytoplasmic organelles developed above the decondensing sperm chromatin. It was a transitory structure which disappeared when the male pronucleus (PN) was formed. The second meiotic division of the oocyte resumed soon after sperm incorporation; abstriction of the second polar body occurred by 3–4 h PI; the polar body constriction was associated with microfilaments.Both the male and female PN were formed at 5 h PI and were surrounded by nuclear envelopes containing pore complexes. The female PN was characterized by patches of condensed chromatin; the male PN was closely associated with the sperm neck and proximal midpiece. Thereafter the PN migrated toward the center of the egg, where the spindle of the first cleavage division was observed at 21 h PI.Dispermic ova analyzed at 2–4 h PI contained 2 decondensing sperm heads and 2 fertilization cones which have reached the same stage, thus suggesting that a few sperm may penetrate quite simultaneously. Multipronucleate eggs were characterized by disturbance of the PN migration.
Human sperm nuclei can transform into condensed chromosomes in Xenopus egg extracts
Authors: Ohsumi Keita , Katagiri Chiaki , Yanagimachi Ryuzo 
Published: February 2005

AbstractThe conditions necessary for inducing pronucleus formation and chromosome condensation of human sperm nuclei were studied using Xenopus egg extracts. When lysolecithin (LC)‐and dithiothreitol (DTT)‐treated spermatozoa were incubated with egg extract prepared with an extraction medium containing 10 mM EGTA, sperm nuclei transformed into chromosomes, bypassing the pronuclear stage. On the contrary, LC‐DTT‐treated spermatozoa incubated in egg extract without EGTA mimicked LC‐permeabilized Xenopus spermatozoa in that they underwent pronucleus formation accompanied by DNA synthesis and subsequent chromosome condensation in the correct chronological order. These observations suggest the importance of intracellular calcium for regulating the states of nuclear chromatin. LC‐permeabilized human spermatozoa were not responsive to the egg extract without any additives, but formed pronuclei when incubated with the egg extract supplemented with 5–10 mM DTT. However, subsequent chromosome condensation of sperm nucleus did not occur in the DTT extract. This suggests that disulfide‐reducing agent blocks transformation of sperm pronuclei into condensed chromosomes.
Protein‐carbohydrate complementarity in mammalian gamete recognition
Authors: Macek Mary Beth , Shur Barry D. 
Published: February 2005

AbstractRecent studies suggest that gamete recognition in a number of species is mediated by complementary proteins and carbohydrates on opposing gamete surfaces. Studies in invertebrates and vertebrates have shown that carbohydrate‐binding proteins on the sperm surface recognize and bind to complementary glycoconjugates on the egg's extracellular coat. This chapter reviews our current knowledge of gamete recognition in the mouse. The complementary receptors for both mouse sperm and egg have been identified, purified, and characterized. Their synthesis during gametogenesis has been defined, as have the effects of sperm capacitation and of the acrosome reaction on their expression and distribution. Their relationship to gamete receptors that function in other species is discussed. Finally, evidence is presented that suggests that one of the receptors that mediate mouse gamete recognition belongs to a family of cell surface receptors that function during multiple cellular interactions in development.
Gonadotropin‐induced murine oocyte maturation in vivo is not associated with decreased cyclic adenosine monophosphate in the oocyte‐cumulus cell complex
Authors: Eppig John J. , Downs Stephen M. 
Published: February 2005

AbstractThe cyclic adenosine monophosphate (cAMP) content of intact oocyte‐cumulus cell complexes at various times after the induction of oocyte maturation in mice in vivo was correlated with the time of commitment by the oocytes to undergo germinal vesicle breakdown (GVB) and metabolic coupling between the oocyte and cumulus cells. Seventy‐nine percent of the oocytes either underwent GVB or were committed to do so by 2 h after injection of human chorionic gonadotropin (hCG). This occurred without a decrease in the coupling between cumulus cells and the oocyte and with increasing cAMP levels in the oocyte‐cumulus cell complex. Maintenance of threshold levels of cAMP within mammalian oocytes appears essential for the maintenance of meiotic arrest, but data presented here suggest that oocyte maturation in mice is induced by gonadotropins in nonatretic follicles in vivo by some mechanism other than one which decreases the cAMP content of the intact oocyte‐cumulus cell complex.
Cholesterol efflux from bovine sperm. I. Induction of the acrosome reaction with lysophosphatidylcholine after reducing sperm cholesterol
Authors: Ehrenwald Eduardo , Parks John E. , Foote Robert H. 
Published: February 2005

AbstractMethods were developed to quantitatively reduce the cholesterol (Chol)/phospholipid (PL) ratio of bovine sperm and to determine the effectiveness of this treatment in capacitating sperm. Washed sperm (2 × 108) were incubated in 1.0 ml of modified Tyrode's solution (TS) containing unilamellar liposomes of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and [14C]‐Chol (35:35:30 molar ratio, 300 nmol total PL). [3H]‐triolein was included as a nonexchangable marker. After 90 min at 39°C, a 13% net exchange of [14C]‐Chol from liposomes to sperm was observed (n = 4), and sperm motility was 80%. Sperm were then washed and 50 × 106 sperm were incubated as before with PC/PE liposomes containing no Chol. After 90 min, sperm were separated from liposomes by centrifugation. Measurement of [14C]‐Chol in the liposomes (supernatant) and parallel gas chromatographic analysis of extracted, saponified liposomes (n = 4) indicated that 30% of sperm Chol was removed by this procedure. Chol efflux decreased percent motile sperm by less than 10% but reduced sperm velocity by more than 50%. Sperm incubated with no liposomes (control), with liposomes containing Chol ( + Chol), and with Chol‐free liposomes (—Chol) were washed and resuspended in TS with 0.2% BSA and 30 μg lysophosphatidylcholine (LPC)/mg bovine serum albumin (BSA). Percent sperm undergoing the acrosome reaction (AR) upon incubation with LPC‐BSA was used as a measure of sperm capacitation. After 60 min of exposure to LPC‐BSA at 39°C, the mean (± SE) percent motile sperm for control, +Chol, and —Chol treatments was 57.0 ± 4.9, 60.0 ± 4.7, and 57.0 ± 6.8, respectively. Corresponding values for percent AR were 14.0 ± 3.4, 20.3 ± 4.4, and 39.7 ± 1.2. These results suggest that loss of Chol from bovine sperm may be an early step in sperm capacitation in this species.
Influence of image sampling frequency on the perceived movement characteristics of progressively motile human spermatozoa
Authors: Mortimer D. , Serres C. , Mortimer S. T. , Jouannet P. 
Published: February 2005

AbstractTracks of 30 progressively motile washed human spermatozoa were plotted manually from 200‐Hz frame rate video recordings. Tracks at 100, 66.7, 50, 40, 33.3., 25, 20, 10, and 5 Hz were then constructed using every 2nd, 3rd, 4th, 5th, 6th, 8th, 10th, 20th, or 40th point. The 200‐Hz tracks were analyzed by traditional manual methods, and all ten sets of tracks analyzed using a computer‐assisted method (“Videomot,” developed originally to analyze 30‐Hz tracks) to eliminate observer bias. Progression velocity (VSL) remained constant under all analysis conditions. Average path velocity (VAP) also remained essentially constant, although Videomot was less reliable at high frame rates due to problems in determining the average path. Curvilinear velocity (VCL) was very frame rate dependent (the 25‐Hz mean value was only 56.5% of that at 200 Hz), and Videomot was more accurate than manual analysis at 200 Hz. Values of the amplitude of lateral head displacement (ALH) were acceptable at most frame rates. At < 66.7 Hz the inclusion of spurious curvilinear track deviations caused lower mean ALH values, and at 5 Hz ALH could not be measured since the track was essentially the average path. Beat/cross frequency (BCF) was also frame rate dependent; at high rates there was the same problem as with ALH measurements, while at ⩽ 25 Hz the maximum BCF was restricted by the frame rate. We conclude that human sperm movement characteristics can be measured at frame rates ca. 30 Hz but only if the constraints affecting VCL and BCF values are understood and accepted. Finally, < 10 Hz can only give values for VSL and, perhaps, VAP.