bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of gonadotropins upon the incidence and kinetics of meiotic maturation of macaque oocytes in vitro
Authors: Schramm Ralph D. , Tennier Michael T. , Boatman Dorothy E. , Bavister Barry D. 
Published: February 2005

AbstractThe specific aim of this study was to determine the effects of gonadotropins in vitro upon the incidence of and precise time interval to germinal vesicle breakdown (GVB) and extrusion of the first polar body (PB1) in oocytes from nonstimulated rhesus monkeys. Cumulus‐enclod germinal vesicle (GV) stage oocytes from 10 normal, cycling rhesus monkeys in the follicular phase of the menstrual cycle were cultured with either: (1) 1.0 μg/ml human follicle‐stimulating hormone (hFSH), (2) 10 μg/ml human luteinizing hormone (hLH), (3) 1.0 μg/ml hFSH and 10 μg/ml hLH, or (4) no gonadotropins (controls). Oocytes (n = 234) were examined at 3‐hr intervals from 0 to 21 hr and at 4‐hr intervals from 24 to 52 hr for GVB and PB1. Neither the incidence of GVB (hFSH: 63.5%; hLH: 56.1%; both gonadotropins: 63.1%; no gonadotropins: 53.6%) nor extrusion of PB1 (hFSH: 41.3%; hLH: 36.4%; both gonadotropins: 36.9%; no gonadotropins; 31.9%) differed (P > 0.05) among treatments. The time to GVB was accelerated (P < 0.05) by gonadotropins (hFSH: 10.8 ± 1.7 hr; hLH: 10.1 ± 1.8 hr; both gonadotropins: 8.8 ± 1.1 hr) when compared to controls (17.4 ± 2.0 hr). However, the time interval to extrusion of PB1 did not differ (P > 0.05) among treatments (hFSH: 32.3 ± 1.2 hr; hLH: 35.1 ± 1.4 hr; both gonadotropins: 35.2 ± 1.3 hr; no gonadotropins: 34.1 ± 1.2 hr). The mean interval to extrusion of PB1 was 34.1 ± 0.6 hr. In conclusion, GVB and PB1 extrusions appear to be, in part, independently regulated events in macaque oocytes matured in vitro since the timing of PB1 extrusion is not tightly coupled with the onset of GVB. Although the developmental potential of oocytes may be enhanced by gonadotropins, alternative approaches must be developed to improve the poor competence of oocytes from nonstimulated monkeys to mature in vitro. © 1994 Wiley‐Liss, Inc.
Developmentally regulated expression during gametogenesis of the murine gene meg1 suggests a role in meiosis
Authors: Don Jeremy , Winer Martin A. , Wolgemuth Debra J. 
Published: February 2005

AbstractPrevious studies have shown that in adult male mice, expression of the meg1 gene is restricted to meiotic and early postmeiotic testicular germ cells. We have now analyzed the expression of meg1 during postnatal testicular development and the comparable meiotic stages in the female. The 0.75 kb transcript for meg1 begins to accumulate in testes at d8‐9 of postnatal (pn) development, coincident with the entry of germ cells into meiosis, and is expressed most abundantly at pn d14 and subsequent stages, when the spermatocytes have entered pachytene. In situ hybridization analysis shows that meg1 is expressed at very low levels in leptotene cells and increases as the cells progress through zygotene and pachytene stages. In the embryonic ovary, meg1 is not detected until after day 15 of gestation when the cells have entered the pachytene stage of meiosis I. In situ hybridization analysis suggests that meg1 transcripts are expressed at higher levels in degenerating rather than in healthy pachytene stage oocytes; meg1 is not expressed in any cells of the adult ovary, regardless of the stage of follicular development. These results suggest that meg1 is indeed a meiosis‐associated gene in both male and female germ cells through the pachytene stage of meiosis I and appears to exhibit sex‐specific differences in its expression thereafter. © 1994 Wiley‐Liss, Inc.
Early gestational expression of retinol‐binding protein mRNA by the ovine conceptus and endometrium
Authors: Doré Jules J. E. , Roberts Mary P. , Godkin James D. 
Published: February 2005

AbstractCommunication between the mother and the early developing embryo is mediated by a variety of signals secreted by either the uterus or the embryo to elicit a response from the other. These signals include prostaglandins, proteins, and steroids. Recently, retinol‐binding protein (RBP) has been described as a product of both the conceptus and endometrium in several species. Utilizing a cDNA clone to bovine RBP, we have described RBP mRNA expression in the endometrium, early conceptus, and extraembryonic membranes of sheep. Endometrial RBP mRNA expression did not differ between samples collected on day 13 of the estrous cycle and early pregnancy. In cyclic animals, RBP mRNA expression decreased two‐fold between days 13 and 16, presumably a result of luteal regression and the consequential withdrawal of progesterone. In pregnant animals, endometrial RBP mRNA expression likewise decreased between days 13 and 16 and remained at this reduced level through day 30, despite the presence of a functional corpus luteum. Initiation of embryonic RBP expression appeared to coincide with early stages of blastocyst elongation at day 13. Levels of expression increased dramatically with conceptus development, peaked on day 23, and declined afterwards. Results from restriction enzyme analysis of genomic DNA indicated that RBP was encoded by a single gene per haploid genome. Differences in the temporal and tissue‐specific expression of the protein, despite the apparent utilization of a single gene, suggest complex regulation of RBP gene expression. © 1994 Wiley‐Liss, Inc.
Calcium concentration and fertilization by subzonal insemination of a single spermatozoon in mouse oocytes
Authors: Fujimoto Goro , Tsuchiya Hideki , Kobayashi Kazuhiko , Saga Masahiko , Rothman Cappy M. , Ogawa Shyoso 
Published: February 2005

AbstractThe effect of calcium concentration in culture medium on the fertilization of subzonally microinseminated mouse oocytes was examined. Oocytes were injected with a single spermatozoon so that the sperm head was forced to adhere onto the ooplasmic membrane with a micromanipulation technique. For the inseminations, epididymal spermatozoa preincubated in culture medium and those treated with ionophore A23187 were used. Inseminated oocytes were cultured using media with three different calcium concentrations of 1.71, 3.42, and 5.13 mM; 40.0%, 71.6%, and 47.9% of oocytes microinjected with preincubated sperm were fertilized after incubation with those media, respectively. When the oocytes inseminated with ionophore‐treated sperm were incubated in media containing 1.71 and 3.42 mM calcium, their fertilization rates were 58.2% and 87.5%. Thus fertility of subzonally microinseminated oocytes was obviously enhanced when cultured in medium with 3.42 mM of calcium, irrespective of being inseminated with preincubated sperm (P < 0.01) or with ionophore‐treated sperm (P < 0.005). Some of the microinseminations with preincubated sperm were performed without sperm adhered to the oolemma. In these cases, the incidence of fertilization was not improved by incubating the inseminated oocytes in medium containing 3.42 mM calcium (32.6%) as compared to those incubated in medium with 1.71 mM calcium (28.3%). These results suggest that the concentration of extracellular calcium exerts an important effect on the progress of fertilization events subsequent to sperm adherence onto the ooplasmic membrane. Almost 80% of the zygotes fertilized via incubation in medium with 3.42 mM of calcium developed into blastocysts after culturing in vitro. © 1994 Wiley‐Liss, Inc.
Bovine nuclear transfer embryos: Oocyte activation prior to blastomere fusion
Authors: Stice Steven L. , Keefer Carol L. , Matthews Lee 
Published: February 2005

AbstractSuccessful bovine nuclear transfer (NT) embyro production requires proper oocyte activation and transfer of a nucleus into this oocyte. However, the temporal relationship between these two events is unclear. The current study examined whether activation of the oocyte prior to fusion would induce nuclear swelling while also affecting development to morula and blastocyst stage and finally development to offspring. Aged oocytes can be activated by a number of techniques including exposure to room temperature. In this study oocyte activation was induced through three different means: reduced temperature culture alone, reduced temperature culture and calcium ionophore, and naturally, through the fertilization process. Electrofusion was carried out after the activation stimulus. When used in the NT procedure, activation of oocytes prior to fusion resulted in NT embryos that under went nuclear swelling and had a high developmental rate to morula and blastocyst stages. Also, these NT embryos developed to normal offspring when transferred to recipient animals. The addition of a calcium ionophore treatment to the reduced temperature culture was not beneficial and resulted in less nuclear swelling. The use of enucleated fertilized oocytes as recipient cytoplasm for the new nucleus resulted in NT embryos developing to morula and blastocyst stages at the same rate as room temperature activated NT embryos. Therefore, improved embryo development can be obtained from NT embryos if the aged recipient oocyte is activated prior to the time of fusion. Also, offspring were obtained from these pre‐activated NT embryos. © 1994 Wiley‐Liss, Inc.
Evidence for presence of hyaluronan binding protein on spermatozoa and its possible involvement in sperm function
Authors: Ranganathan Sripriya , Ganguly Amit Kumar , Datta Kasturi 
Published: February 2005

AbstractHyaluronic acid, a major component of the extracellular matrix, plays an important role in the regulation of different cellular processes, e.g., locomotion, cell‐cell interaction during morphogenesis, and differentiation. Distribution of hyaluronic acid with respect to the role of sperm hyaluronidase in sperm penetration and gamete interaction is well established. In order to elucidate this mechanism, in our current study we have identified and demonstrated, for the first time, the presence of a 68‐kDa cell surface hyaluronic acid binding glycoprotein (HABP) in spermatozoa of different species (rat, mice, bull, and human) by immunoblot analysis and indirect immunofluorescence using the polyclonal antibodies raised against purified HABP. Furthermore, we were able to demonstrate a differential distribution of 68‐kDa HA binding protein on the sperm head, midpiece, and tail of different species. To identify its role in sperm function, we observed its declining pattern during epididymal maturation and also the inhibition of sperm‐oolemmal adherence by pretreatment of the sperms with anti‐HABP antibodies. We have further observed its in vivo phosphorylation in motile spermatozoa. All our data clearly indicate that sperm hyaluronan binding protein may have a specific role in sperm maturation, motility, and fertilization processes. © 1994 Wiley‐Liss, Inc.
MPF components and meiotic competence in growing pig oocytes
Authors: Christmann Leandro , Jung Thomas , Moor Robert M. 
Published: February 2005

AbstractGrowing pig oocytes (≤90 μm in diameter) are unable to resume meiosis in vitro. The objective of our present experiments has been to identify the reasons for meiotic competence in these cells. By comparing histone H1 kinase activity in growing and fully grown oocytes we demonstrate that incompetence is associated with an inability to activate H1 kinase in growing oocytes. Immunoblotting was used to determine whether this kinase inactivity resulted from a lack of either p34cdc2 protein or B‐type cyclin. The results established that each of these cell cycle molecules are present in comparable amounts in both growing and fully grown oocytes. In the third series of studies experiments were carried out in an attempt to induce p34cdc2 activation during growth. Treatment with okadaic acid, an inhibitor of phosphatase 1 and 2A known to stimulate and accelerate the transition into M‐phase of the meiotic cycle in a number of different species, was able to induce p34cdc2 kinase activity and facilitated the G2‐ to M‐phase in growing oocytes.We conclude that although growing oocytes in pigs have sufficient key cell cycle components for the G2 to M transition, they remain incapable of converting these components to active maturation‐promoting factor (MPF) until growth is virtually completed. Inhibition of phosphatase 1 or 2A induces the formation of active MPF during growth by an as yet unidentified pathway. © 1994 Wiley‐Liss, Inc.
Computerized analysis of the motility parameters of hamster spermatozoa during maturation
Authors: Devi L. Girija , Shivaji S. 
Published: February 2005

AbstractA computer‐aided semen analysis system was used for the objective assessment of hamster spermatozoa during epididymal maturation. The caput epididymal spermatozoa were extremely sluggish, achieved very little progression, and the three velocity parameters, namely curvilinear velocity (VCL), progressive velocity (VSL), and path velocity (VAP), were low. These spermatozoa during progressive movement alternated between the linear shape and “U” shape or attained an “S” shape prior to changing to the “U”; shape. The corpus epididymal spermatozoa were faster, displayed greater VSL, VAP, and VCL compared to caput epididymal spermatozoa, and, during forward motility, attained “U,” “C,”; and (or) “?” shape as in the wriggling motility pattern. The proximal cauda epididymal spermatozoa were actively motile and VSL, VAP, and VCL in these spermatozoa were more than 10 times greater compared to the caput epididymal spermatozoa. The proximal cauda epididymal spermatozoa predominantly moved in circles and with time became slower and more circular in their trajectories and exhibited a reduction in LIN (linearity). The distal cauda epididymal spermatozoa were very similar to the proximal cauda epididymal spermatozoa with respect to their fast motility (VSL, VAP, and VCL are similar) and beat cross frequency (BCF), but showed larger values for STR (straightness) and LIN and moved along curved trajectories. The amplitude of lateral head displacement (ALH) was also considerably lower in the distal cauda epididymal spermatozoa compared to the proximal cauda epididymal spermatozoa. Thus, this study provides for the first time data related to seven motility parameters for caput and corpus epididymal spermatozoa of hamster. It also provides additional data with respect to VCL, LIN, BCF, and ALH for proximal and distal cauda epididymal spermatozoa of hamster. © 1994 Wiley‐Liss, Inc.
Effects of transforming growth factors and activin‐A on in vitro porcine oocyte maturation
Authors: Coskun Serdar , Lin Young C. 
Published: February 2005

AbstractGrowth factors are known to regulate ovarian function. In the present study, effects of these growth factors, TGF‐α, TGF‐β, and activin‐A were tested on spontaneous porcine oocyte maturation. Cumulus‐oocyte complexes (COC) were cultured in the presence of TGF‐α, TGF‐β, and activin‐A for 48 hr. Stages of meiotic maturation were assessed by staining with acetic orcein. Among these factors, only TGF‐α significantly enhanced the maturation rate, whereas TGF‐β suppressed the spontaneous maturation rate. The site of action of TGF‐α on COC and the interaction between TGF‐α and EGF receptor was also examined. Denuded oocytes, alone or in coculture with cumulus cells, were cultured in the presence of TGF‐α for 48 hr. TGF‐α did not have any significant effect on denuded oocyte maturation. Heptanol was employed to investigate the role of gap junctions on TGF‐α‐induced oocyte maturation in COC. Although heptanol did not have any significant effect in the control medium, heptanol reversed the stimulatory effect of TGF‐α on porcine oocyte maturation. TGF‐α was able to displace 125I‐EGF binding on COC. In conclusion, TGF‐α enhances the spontaneous maturation of porcine oocytes by generating positive signal(s) in cumulus cells that are transferred to the oocyte via gap junctions. TGF‐α shares the same receptor with EGF on porcine COC. TGF‐β, in contrast, inhibits porcine oocyte maturation. © 1994 Wiley‐Liss, Inc.
Actin in the acrosome of the spermatozoa of the crab, Cancer pagurus L. (decapoda, crustacea)
Authors: Tudge C. C. , Grellier P. , Justine J.‐L. 
Published: February 2005

AbstractThe cytoskeletal protein actin was identified in the mature spermatozoon of the European edible crab, Cancer pagurus Linnaeus, by indirect immunofluoresce with monoclonal and polyclonal anti‐actin antibodies, fluorescent phalloidin, and DNAase I. The actin was localized in two distinct concentric rings within the acrosome vesicle of the spermatozoon and appeared to correlate with the internal zonation of the vehicle. Modifications of the fluorescent pattern for actin were observed in sperm cells which were undergoing changes associated with the acrosome reaction. In these cases, fluorescent staining was observed in the nucleocytoplasm immediately subjacent to the perforatorial column and sometimes in the perforatorial column within the acrosome vesicle. Equally intense fluorescence was observed in an apical perforatorial projection. SDS‐PAGE of C. pagurus sperm confirmed the presence of actin in the cells. A single band of actin (approximately 43 kDa) comigrated with rabbit muscle actin when immunoblotted onto nitrocellulose with mouse monoclonal anti‐actin. The actin‐associated cytoskeletal proteins α‐actinin, tropomyosin, and spectrin were also identified within the spermatozoon of C. pagurus using specific polyclonal antibodies, but their presence was not confirmed by SDS‐PAGE and immunoblotting. © 1994 Wiley‐Liss, Inc.
Development of IVM‐IVF produced 8‐cell bovine embryos in simple, serum‐free media after conditioning or Co‐culture with buffalo rat liver cells
Authors: Rehman N. , Collins A. R. , Suh T. K. , Wright R. W. 
Published: February 2005

AbstractDevelopment of 8‐cell bovine embryos derived from in vitro matured/in vitro fertilized (IVM/IVF) oocytes was evaluated in two simple, serum‐free media (CZB and SOM) with buffalo rat liver cells co‐culture (BRLC) or after conditioning compared to a commonly used, serum‐supplemented complex medium TCM‐199. In a 3 x 4 factorial design, 578 eight‐cell embryos were randomly assigned to 12 treatment groups. The factors were: first, type of culture medium (M199/FBS, CZBg and SOM), and second, the use of BRLC (as co‐culture or to condition media for 24 hr and 48 hr) and unconditioned media. Development to morula was not affected by the type of medium, but co‐culture and 48 hr conditioning within media type resulted in better development when compared to the 24‐hr conditioned or unconditioned groups. Blastocyst development in SOM (38.9%) was different (P < 0.05) than in CZBg (46.6%) and M199/FBS (48.7%) and was lowest in the unconditioned group (27.8%) followed by 24 hr conditioned (33.3%), 48 hr (56.3%), and co‐culture (59.6%). No blastocyst expansion was observed with unconditioned media and 24 hr conditioned SOM. Significant differences (P < 0.05) were found among all treatment groups except the co‐culture and 48‐hr conditioned groups. Hatching occurred only with co‐culture and 48‐hr conditioned groups of M199/FBS and CZBg media. These data show that CZB with glucose conditioned by BRLC monolayers for 48 hr can support the development of IVM/IVF produced bovine embryos to blastocyst compared to culture in TCM‐199 with serum. © 1994 Wiley‐Liss, Inc.
Induction of meiotic maturation in vivo in the mouse by IMP dehydrogenase inhibitors: Effects on the developmental capacity of ova
Authors: Downs Stephen M. 
Published: February 2005

AbstractThe present study was conducted to examine the effects of priming duration and inosine monophosphate (IMP) dehydrogenase inhibitors on the fertilization and pre‐ and postimplantation development of ova from immature mice. Mice were primed with equine chorionic gonadotropin (eCG) and 1 d later were treated with mycophenolic acid (MA) or mizoribine (Mz; also known as bredinin) or an equal volume of the vehicle. Two days after priming, mice received human chorionic gonadotropin (hCG) and were mated with fertile males. Some mice received hormone but were not mated. Ova were isolated from the oviducts 23–24 hr post‐hCG and cultured in Whitten's medium. Some mice were not killed until 7 or 19 d postvaginal plug to determine the extent of implantation or development to term, respectively. In superovulated control mice, 94% of ova developed to two‐cells and 82% of these progressed to the blastocyst stage. Nineteen of 23 mice (83%) had implantations (24/mouse) and 20 of 24 mice (83%) had term embryos (11/mouse). Induction of meiotic maturation with Mz or MA after 1 d of priming, followed 1 d later by hCG injection and mating, resulted in a significant loss of preimplantation developmental capacity (20–22% two‐cells; 29–50% blastocysts). These numbers were similar whether or not the mice were mated, indicating that the development was parthenogenetic. In addition, Mz treatment reduced the number of mice with implantion sites (13 of 19, 68%), the number of implantations per mouse (10), the viability of the implantations, and development to term (four of 24, mice, 17%; one embryo/mouse). Thus, most of the implanted embryos were resorbed after imlantation. This effect could be attributed, in part, to each of the following: (1) parthenogenetic activation; (2) aging of the metaphase II oocyte before insemination; and (3) resumption of meiotic maturation before the oocyte had reached its full developmental potential. Coincident gonadotropin injection reversed the loss of development brought about by IMP dehydrogenase inhibitors. These data show that induction of premature meiotic maturation by IMP dehydrogenase inhibitors results in a significant loss of developmental capacity and indicates that active purine metabolic pathways in situ maintain meiotic arrest and prevent premature meiotic maturation that would result in compromised development. © 1994 Wiley‐Liss, Inc.
Evidence against a functional ATP‐dependent calcium extrusion mechanism in bovine epididymal sperm
Authors: Vijayaraghavan Srinivasan , Trautman Kevin , Mishra Santosh K. , Herrmsmeyer Kent 
Published: February 2005

AbstractBovine epididymal sperm resuspended in ionic buffers take up relatively large amounts of calcium. This uptake, which is almost entirely mitochondrial, apparently bypasses the sperm cytosol. The direct mitochondrial loading is an unusual aspect of sperm calcium uptake, which suggests that the plasma membrane region surrounding the mitochondria should be highly permeable to calcium, whereas the membrane domains surrounding the head and tail regions of sperm should be impermeable. This study was undertaken to determine the role of a plasma membrane calcium ATPase in sperm calcium homeostasis. Kinetics of calcium (45Ca2+) uptake into intact and permeabilized caudal epididymal sperm confirmed that mitochondrial calcium uptake occurs with virtually no resistance from the surrounding plasma membrane. Cytoplasmic calcium accumulation by sperm depleted to intracellular ATP, measured in the presence of mitochondrial calcium uptake inhibitors, showed no increase upon energy depletion as would be expected if an ATP‐dependent calcium extrusion mechanism were present. Furthermore, lowering the incubation temperature to further reduce the activity of the calcium ATPase in these energy‐depleted sperm was also without effect on calcium accumulation. The calcium ATPase inhibitor vanadate, even at high concentrations, failed to increase intracellular 45Ca2+ accumulation. However, vanadate was effective in inhibiting motilty showing that the compound was accumulated into sperm to inhibit flagellar dyenin ATPase. Therefore, the lack of effect of vanadate on 45Ca2+ accumulation was not due to its inability to enter sperm. Other calcium ATPase inhibitors such as quercetin, thapsigargin, and cyclopiazonic acid, which readily demonstrate ATP‐dependent calcium extrusion in other somatic cells, were also without effect on sperm caclium accumulation. These results with 45Ca2+ were also confirmed using single‐cell calcium distribution measurements with a fluorescent indicator. Our data strongly suggest that sperm, contrary to previous assumptions, do not possess a functional plasma membrane, ATP‐dependent, calcium extrusion mechanism. © 1994 Wiley‐Liss, Inc.