bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ultrastructural organization of the mature spermatozoon of Luidia clathrata (Say) (Echinodermata: Asteroidea)
Authors: Dehn Paula F. , Hinsch Gertrude W. 
Published: February 2005

AbstractThe sperm of Luidia clathrata are morphologically typical of asteroid sperm. The head is spherical and contains the nucleus and acrosomal complex. The nucleus has an anterior indentation in which rests the acrosomal complex. There is no evidence of a centriolar fossa along the posterior border of the nucleus. The acrosome is a cup‐shaped structure containing a less electron dense central region. The periacrosomal material is homogeneous in nature, and the subacrosomal specialization of the periacrosomal materials appear as bands of varying electron density. The middle piece is an annular band of mitochondria which surrounds the proximal and distal centrioles. The centrioles exhibit the typical nine triplet arrangement. Both the centrioles and the axoneme project to one side of the middle piece region. Associated with the distal centriole is an elaborate pericentriolar process.
Unilateral tunicamycin sensitivity of gametogenesis in dioecious isogamous chlamydomonas species
Authors: Wiese Lutz , Mayer Robert A. 
Published: February 2005

AbstractSex cell adhesion in isogamous chlamydomonads is caused by a complementarity between sex‐specific mating type substances, glycoproteins anchored in the flagella membrane of (+) and (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop - \limits^. $\end{document}) gametes. The systems of mating type substances are species‐specific and condition, by their individuality, gametic incompatibility between species. The adhesion systems of several species share one common feature: the attainment of the agglutination capacity is sensitive to tunicamycin, but in one sex only. The effect is interpreted as due to the interference of tunicamycin with the synthesis of the mating type substances by blocking of their glycosylation in one but not in the other sex. It is postulated that the tunicamycin‐sensitive gametic adhesiveness depends, within the mating‐type‐specific glycoprotein, on an N‐glycosidically bound ligand of carbohydrate nature. A concept on the origin of sibling species by mutative modulations within the proper ligands of the glycoproteinaceous mating type substances is developed.
Fucosylation of glycoproteins in rat spermatocytes and spermatids
Authors: Grootegoed J. Anton , Krüger‐Sewnarain Bea C. , Jutte Nicolet H. P. M. , Rommerts Focko F. G. , van der Molen Henk J. 
Published: February 2005

AbstractGlycoprotein synthesis in pachytene spermatocytes and round spermatids, isolated from rat testes, was studied by analysis of the incorporation of (3H)‐fucose. The isolated germ cells were capable of incorporating (3H)‐fucose into cell‐bound, acid‐precipitable components for an incubation period of at least 23 hours (at 32°C). In young spermatids, engaged in the formation of the acrosome, (3H)‐fucose was incorporated into more than 16 different glycoproteins within the molecular weight range of 20.000–100,000. A qualitatively similar set of glycoproteins was found to be labeled in spermatocytes. Radioautography showed that after 4 hr most of the incorporated radioactivity was present at one pole in the perinuclear zone of spermatocytes and spermatids, which could reflect incorporation of fucose in the Golgi apparatus. The newly fucosylated glycoproteins were associated with a particulate subcellular fraction (membrane fraction). Trypsin treatment of whole cells after 25 hours of incubation with (3H)‐fucose, however, did not cause significant lysis of tritiated glycoproteins.From the results it was concluded that the majority of the newly fucosylated glycoproteins in spermatocytes and spermatids remained associated with an intracellular membrane system, presumably the Golgi apparatus and the vesicles that arise from this structure, to be deposited subsequently in proacrosomic granules and the acrosome. The results also suggest that initiation of the synthesis of spermatidal glycoproteins occurs during the prophase of meiosis in spermatocytes.
“Spontaneous” hardening of the zona pellucida of mouse oocytes during in vitro culture
Authors: de Felici Massimo , Siracusa Gregorio 
Published: February 2005

AbstractCulture in vitro causes a slow, progressive hardening of the zona pellucida (ZP) of fully grown dictyate oocytes isolated from the mouse ovary. Hardening cannot be prevented by inhibitors of peroxidase or by a tyrosine analogue. Culture in anaerobic conditions is very effective in preventing ZP hardening. If the oocyte is cultured surrounded by its own follicle cells or in contact with cumuli oophori obtained from superovulated females, hardening is much reduced. The results suggest that the “spontaneous” hardening in cultured ovarian oocytes is not due to a cortical reaction, and that a diffusible factor is produced by follicle cells that protect the ZP from hardening.
Interaction of human sperm with zona‐free hamster eggs: A freeze‐fracture study
Authors: Koehler James K. , Decurtis Ivan , Stenchever Morton A. , Smith Dianne 
Published: February 2005

AbstractAn ultrastructural study has been carried out on the interaction of human sperm with zona‐free hamster oocytes. Scanning, thin‐section, and freeze‐fracture electron microscopy were used to examine sperm in the process of contacting and fusing with the egg surface. Microvilli from the oocyte attach to the sperm head at anterior and posterior loci, initial contact often being made with the inner acrosomal membrane. Freeze‐fracture study reveals that microvilli specifically contact particle‐rich regions of the sperm head surface, and fusion with the oolemma occurs in the equatorial region of the spermatozoon. Intramembranous particle aggregation was observed on the postacrosomal and neck regions of spermatozoa and resulted from glutaraldehyde fixation and glycerolation, since fast freezing of unfixed specimens did not show patching. Counts of intramembranous particles on sperm head plasma membranes showed a reversal of the usual P face/E face ratios for unfixed, fresh sperm, whereas capacitated populations retained the usual particle distributions on P and E faces, even in unfixed, fresh samples. It is suggested that a switching of binding properties of integral proteins may occur during capacitation, resulting in a higher stability of the P‐face association in unfixed cells.
Reproduction in mice: The fate of spermatozoa not involved in fertilization
Authors: Watson J. Gary , Carroll Joseph , Chaykin Sterling 
Published: February 2005

AbstractMechanisms were sought through which the control of preimplantation mouse embryo development by spermatozoa might be effected. A potential route for the transmission of sperm‐dependent stimuli to C3HeB/FeJ females was uncovered. It was found that within 24–48 hr after artificial insemination with spermatozoa, in which the DNA had been labeled with tritiated thymidine, a minimum of 9% of the radioactivity was transported across the uterine walls. It was deposited among the maternal tissues in a pattern that differed from the patterns of isotope distribution obtained when either free tritiated thymidine or Escherichia coli cells containing DNA labeled with tritiated thymidine were used instead of labeled sper‐matozoa. In sperm‐treated animals the ovaries, the adrenals, and a mesenteric lymph node exhibited strikingly large accumulations of radioactivity. The heart, spleen, and uterus manifested lesser accumulations of label, but were higher than liver, kidney, lung, brain, muscle, and intestine. The specific activity of the lymph node was found to decrease during the 12–72‐hr period following insemination. This result led to the hypothesis that the lymphatic system could serve as a route for the dissemination, to maternal tissues, of radioactivity originally associated with spermatozoa deposited in the uterus. Heat‐inactivated spermatozoa, which have the potential for facilitating the first cleavage of fertilized embryos, exhibited a distribution pattern indistinguishable from untreated spermatozoa. Sperm protein kinase was found to survive the heat inactivation of spermatozoa. This stability was interpreted as being compatible with the kinase functioning as an intermediary in the transmission of sperm‐dependent stimuli that control preimplantation embryo development in mice.
Acid release, cytoplasmic alkalinization, and chromosome condensation during sea urchin fertilization and amine‐lnduced parthenogenesis
Authors: Lois Augusto F. , Neill Dori J. , Carroll Edward J. 
Published: February 2005

AbstractWe have studied the relationship between acid release, cytoplasmic alkalinization, and the extent of chromosome condensation during parthenogenetic activation of sea urchin eggs. The relative rate of acid release in Strongylocentrotus purpuratus eggs was determined from pH measurements of egg suspensions. Acid release in inseminated eggs began after a lag of 0.4 min and the relative rate increased 108‐fold, declined, and release was essentially complete by 8‐min postinsemination. An average of 3.8 ± 0.23 × 10−12moles H+ cell− was released as determined by backtitration with NaOH. Acid release characteristics of eggs parthenogenetically activated with either NH4C1, methylamine ethylamine, n‐propylamine, n‐butylamine, or benzylamine were qualitatively similar. There was no detectable lag peroid and the increase in relative rate of acid release was directly proportional to the carbon number of the amine used, eg, from 8.3‐fold methylamine to 470‐fold with benzylamine. The total equivalents of acid released ranged from 0.50–8.2 × 10−12 moles H+·cell− in direct proportion to the concentration of amine used. The degree fo cytoplasmic alkalinization induced as a function of methylamine and benzylamine concentration was determined by pH measurements fo egg homogenates; egg cultures were also prepared for microscopic examination of chromosome condensation. None of the eggs had condensed chromosomes at 0.5‐mM methylamine whereas a cytoplasmic alkalinization of 0.6 pH units was observed. Increased methylamine levels up to 10mM resulted in chromiosome condensation in only 20% of the eggs. A similar result was found with benzylamine. We conclude that acid release and cytoplasmic alkalinization during chemical parthenogenesis are insufficient to mimic sperm induction of chromiosome condensation and suggest that an additional factor(s) is required for chromosome condensation by low concentration of amines.
Incorporation of L‐3H‐fucose in the rete and ovary of the fetal mouse
Authors: Jagiello Georgiana M. , Dennis James , Hiura Masamichi , Ducayen Mercedes B. 
Published: February 2005

AbstractThe concept of Byskov which hypothesizes a glycoprotein inducer of meiosis for the mammalian fetal ovary has been tested by examining the incorporation of the specific precursor 3H‐fucose into the rete ovarii of day 14 mouse ovaries. Semiquantitation of grains in autoradiographs has documented a concentration over the rete ovarii which exceeded that over the oogonia, ovarian fibroblasts, or surface epithelia. These data support the concept that the cytoplasm of mouse rete ovarii is capable of synthesizing a glycoprotein that may be the meiosis‐inducing substance.
Ultrastructural studies of spermatozoa in three bivalve species with notes on evolution of elongated sperm nucleus in primitive spermatozoa
Authors: Franzén Åke 
Published: February 2005

AbstractSperm ultrastructure and spermiogenesis of the three bivalve species Musculus discors, Nucula sulcata, and Dreissena polymorpha have been studied. During spermatid differentiation in Musculus discors and Nucula sulcata the nucleus attains an elongated rod‐like shape. The spermatozoon from Nucula sulcata was found to have a cup‐shaped acrosome and five mitochondria surrounding two centrioles in the middle piece. The spermatozoa from Musculus discors has a long complex acrosome. From the distal centriole striated processes extend and attach to the plasma membrane. The spermatozoon of the fresh water species Dreissena polymorpha agrees in all main features with those of other invertebrate groups with external fertilization. It is thus of the primitive type with barrel‐shaped nucleus and four to five mitochondria1 spheres in the middle piece. The acrosome is a prominant, complex structure at the apex of the mature spermatozoon.A comparison of sperm ultrastructure among bivalves indicates that there is a certain correlation between the evolution of the elongated sperm nucleus and large, yolk‐rich eggs. In species with an elongated sperm nucleus the increased egg size has often led to a lecithotrophic or direct development. The elongated nucleus is a slight modification of the primitive type. There is a great variation in acrosome structure among bivalve spermatozoa, reflecting diverging functional demands at fertilization of the eggs.
Human spermatogenic cell marker proteins detected by two‐dimensional electrophoresis
Authors: Narayan Perinchery , Scott B. Keyes , Millette Clarke F. , DeWolf William C. 
Published: February 2005

AbstractHighly homogeneous populations of human pachytene spetmatocytes and round spermatids have been obtained from normal adult testis using unit gravity (STA‐PUT) sedimentation. Contaminating Leydig cells have been removed by density centrifugation in discontinuous Percoll gradients to yield resultant germ cell purities of 90–95% for pachytene spermatocytes and 89–96% for round spermatids. The total cellular polypeptide composition of separated human germ cells has been analyzed by two‐dimensional polyacrylamide gel electrophoresis to compare 1) human and mouse pachytene spermatocytes (species specificity), 2) samples of human spermatocytes obtained from different individuals (allo specificity), and 3) pachytene spermatocytes and round spermatids from the same patients (stage specificity). Mouse and human germ cells have been found to exhibit extensive homology, but identified marker proteins limited to human spermatocytes include a group of polypeptides at p45/5.9 as well as a protein at p67/5.2. Proteins unique to mouse germ cells include component p65/5.5. Comparisons between different preparations of human pachytene spermatocytes have revealed about 90% electrophoretic homology, but some striking allotypic variations have been noted including the proteins at p45/5.9. Finally, presumptive stage‐specific spermatogenic cell markers have been identified including the p45/5.9 polypeptides that are present only in human spermatocytes. Although the physiological roles of particular marker proteins have not yet been determined, the present findings indicate that purified spermatogenic cell populations may be analyzed biochemically to identify constituents important in the regulation of sperm development in man.
Postovulatory aging of human ova: II. Spontaneous division of the first polar body
Authors: Ortiz M. E. , Lucero P. , Croxatto H. B. 
Published: February 2005

AbstractTwo oocytes recovered from the Fallopian tube at 24 and 50 h following the LH peak in plasma were examined by light microscopy and transmission electron microscopy. The possibility of fertilization was excluded by clinical and morphologic evidence. In the earliest specimen, the first polar body showed condensed nuclear chromatin, without nuclear envelope, and is interpreted as entering interphase. In the other specimen, the first polar body was undergoing division, which is interpreted as spontaneous second meiotic division.
Plasma membrane structure in spermatogenic cells of the swordtail (teleostei, Xiphophorus helleri)
Authors: Jonas‐Davies J. A. C. , Winfrey V. , Olson G. E. 
Published: February 2005

AbstractThe plasma membrane of spermatogenic cells of the teleost Xiphophorus helleri was examined ultrastructurally and cytochemically in order to characterize the temporal development of the membrane specializations characteristic of the mature spermatozoon. Mature sperm display a mosaic distribution of Concanavalin A and Ricinus comrnunis I binding sites; the anterior region of the head displays an intense binding that is not seen in other surface regions. This asymmetric binding is evident in early spermatids and the area of lectin binding appears associated with the plasma membrane overlying the nucleus. Transmission electron microscopy reveals that the plasma membrane over the anterior region of the head is characterized by an ordered glycocalyx and a tight adherence to the underlying nucleus. Additional membrane differentiations were revealed both in the midpiece region where a “submitochondrial net” is attached to the plasma membrane and at the base of the axoneme where the plasma membrane possesses a “collar‐like” arrangement of circumferential rings. The possible functions of these differentiations, as well as their correlation to differentiations seen in sperm of other animal groups, are discussed.
Spermatogenic cell differentiation in vitro
Authors: Risley Michael S. 
Published: February 2005

AbstractCulture conditions that support the in vitro development of many spermatogenic stages from the frog Xenopus laevis are described. Spermatogenic cells were dissociated with collagenase and preelongation stages aseptically isolated by density gradient centrifugation in Metrizamide. The cells were then cultured in modified forms of defined nutrient oocyte medium (DNOM). The development of spermatogenic cells was affected significantly by changes in fetal calf serum concentration, cell density, energy sources, and NaCl concentration. Optimum in vitro spermatid development was obtained when spermatogenic cells were cultured at relatively high densities (3–7 × l07 cells/25 cm2) in DNOM modified to contain 10% heat‐inactivated, dialyzed fetal calf serum, 2 mM 1‐glutamine, 0.1 % glucose, 15 mM HEPES buffer (pH 7.4), and 38.3–48.3 mM NaCl. These culture conditions also supported the differentiation of preelongation spermatids and spermatocytes isolated by density‐gradient centrifugation in Metrizamide and subsequent unit gravity sedimentation in gradients of bovine serum albumin. Approximately 95 % of such isolated spermatids and spermatocytes continued differentiating in vitro for 14 days at in vivo rates. Phase‐contrast and electron microscopy of the cultured cells demonstrated that in vitro differentiation was morphologically normal between the leptotene and elongate spermatid stages. Autoradiographic studies of preleptotene development demonstrated that spermatogonia proliferated and preleptotene spermatocytes developed to zygotene in 12‐day cultures. The results suggest that many spermatogenic stages in Xenopus can develop independent of Sertoli cells, and demonstrate that spermatogenic cell cultures can now be used for in vitro studies of spermatogenesis.
Rabbit spermatozoa undergo an acrosome reaction in the presence of glycosaminoglycans
Authors: Lenz R. W. , Bellin M. E. , Ax R. L. 
Published: February 2005

AbstractRabbit‐ejaculated spermatozoa were incubated in a chemically defined medium containing comercially available glycosaminoglycans (GAGs) at concentrations ranging from 0.1 to 100 μg/ml. Sperm were stained and examined for the degree of acrosome reaction and viability after 9 h of incubation. There were significant dose and treatment effects of the induction of the acrosome reaction. Viability did not differ significantly betweendoses or treatment. Heparin enhanced the acrosome reaction between concentrations of 0.1 to 1.0 μg/ml, whereas higher levels depressed the percentage of sperm undergoing the acrosome reaction. Seminal plasma added to sperm cultures depressed the stimulatory effect of GAGs. Treatment of chondroitin‐4‐sulfate with chondro‐4‐sulfatase prohibited the stimulatory effect. It is concluded that GAGs, components of the female reproductive tract, may promote the acrosome reaction so that successful fertilization can occur.
Effect of exposure to high environmental pressure on spermatogenesis in mice
Authors: Dott H. M. , Doré Caroline J. , Foster G. C. A. , Halsey M. J. , Monk Susan , Setchell B. P. , Wardley‐Smith Bridget 
Published: February 2005

AbstractThis study was designed to investigate the mechanism of the subfertility produced when male mice are exposed to high pressure [Baden et al, 1982]. In the first series of experiments, male BALB/c mice were exposed to 50 ATA helium pressure intermittently throughout spermatogenesis (5 weeks). Control mice were exposed to 1 ATA air under identical conditions for an equivalent period. Immediately after exposure half the mice in each group were sacrificed, the remainder being sacrificed 14 days later. Testes were weighed and prepared for histological examination, and spermatozoa were examined for motility and abnormalities. More testes in the pressure group had disorganised seminiferous epithelia and weighed less than the control group; in addition the motility of sperm was also reduced immediately after pressurisation.In the second series, male mice were exposed to 50 ATA pressure, or 1 ATA air intermittently for only 1 week to assess whether this exposure, for a period sufficient only to affect epididymal sperm, had any effect on functional fertility. The males were subsequently mated with untreated females; no difference was seen between the groups for pregnancy rate, preimplantation loss, or fetal survival.These data support the idea that the changes in spermatogenesis causing subfertility in mice are fairly subtle, but are consistent with the premature release of spermatids from seminiferous epithelium. Epididymal sperm remained functionally unaffected by exposure to high pressure.
Nucleolar transformations in the human oocyte after completion of growth
Authors: Tesařík Jan , Trávník Pavel , Kopečný Václav , Kristek František 
Published: February 2005

AbstractNucleolar ultrastrure was studied in fully grown human oocytes obtained from multilaminar preantral follicles and from follicles at different stages of antrum formation. Selective staining for ribonucleoproteins and 3H‐uridine labeling were used in attempt to better understand the nature and functional significance of homogeneous dense nucleoli found in oocytes from large antral follicles.There was an apparent increase in the radio of nucleonema to nucleolar interstices, accompanied by a gradual degranulation of the nucleolonema during early stages of antrum fromation. The process of nucleolar homogenization continued in oocytes from medium‐size antralfollicles, island of more tightly packed fibrils being hybothesized to represent persisting active transcription units. Entirely filamentous and homogeneous nucleoli were typical for oocytes from large antral follicles. They were demonstrated to ribonucleoprotein filaments embedded in pale‐ staining matrix. They were demonstrated to contain newly synthesized RNA after a 30‐min pulse with 3H‐uridine. The described nucleolar transformations are interpreted as acorrelate of nucleolar transition from a site of RNA synthesis into a site of RNA Storage during in human oocyte preovulatory development.
Monensin blocks the first meiotic cell division of the Xenopus oocyte: Effect at the nuclear membrane level
Authors: Marot J. , Tso J. , Huchon D. , Mulner O. , Ozon R. 
Published: February 2005

AbstractThe carboxylic ionophore monensin inhibits the meiotic maturation of the Xenopus oocyte. When oocytes are exposed to high concentrations of monensin (10 μM), both progesterone and MPF‐induced (maturation‐promoting factor‐induced) maturations are blocked. Lower doses of monensin (1–10 μM) do not inhibit the formation or amplification of MPF activity in the oocyte cytoplasm; however, breakdown of the nuclear envelope does not occur. These observations show that monensin, which is known to abolish intracellular proton gradients, interferes with the mechanism of the breakdown of the nuclear envelope induced by MPF.