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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Fragile X Protein Regulates Cellular Proliferation and Oocyte Polarity by Controlling cb1 Levels During Drosophila Oogenesis

Epstein, Andrew Michael January 2008 (has links)
Fragile X Protein (FMRP) is an RNA binding protein linked to the most common form of inherited mental retardation, Fragile X syndrome (FraX). Despite its ubiquitous expression and presence of non-neuronal phenotypes, FMRP function remains understudied outside of neural and synaptic development. In addition to severe cognitive deficits, FraX etiology also includes postpubescent macroorchidism, which is thought to occur due to overproliferation of the germline. Using a Drosophila model for FraX, I have shown that FMRP controls germline proliferation as well as dorso-ventral polarity during oogenesis. dFmr1 null ovaries exhibit egg chambers with increased numbers of germ cells and ventralized embryos. The number of cyclin E and phosphohistone H3 positive cells is increased in dFmr1 germaria compared to wild-type, suggesting that the mutant germline cells exhibit defects in proliferation. In addition, BrdU incorporation is increased during vitellogenesis, consistent with a prolonged S phase for endoreplicating nurse cells. Here I report the FMRP controls the levels of cbl mRNA in the ovary and that the overproliferation and polarity defects found in dFmr1 ovaries can be rescued by reducing cbl dosage in half. These data suggest a model whereby FMRP regulates cellular proliferation and polarity during oogenesis by controlling the E3 ubiquitin ligase cbl.
32

THE JAK-STAT PATHWAY IS REQUIRED FOR MULTIPLE EARLY EVENTS IN DROSOPHILA OOGENESIS

Matlock, Jennifer Renee 01 January 2002 (has links)
The Janus kinase (JAK) pathway is an integral part of signaling through a variety of ligands and receptors in mammals. The extensive reutilization and pleiotropy of this pathway in vertebrate development is conserved in other animals as well. In Drosophila melanogaster, JAK signaling is involved in embryonic pattern formation, sex determination, larval blood cell development, wing venation, planar polarity in the eye, and formation of other adult structures. Here we describe several roles for JAK signaling in Drosophila oogenesis. The gene for a JAK pathway ligand, unpaired, is expressed specifically in the polar follicle cells, two pairs of somatic cells at the anterior and posterior poles of the developing egg chamber. A primary defect of chambers with reduced JAK activity is fusion of successive chambers. These chambers exhibit an expansion of the polar cell population and concomitant loss of interfollicular stalk cells. Mosaic analysis of both JAK pathway transducers, hopscotch and stat92E, reveals that JAK signaling is specifically required in the somatic follicle cells. Another role of JAK signaling is in oocyte localization. In chambers mosaic for loss of hop activity, oocyte mislocalization results. Proper localization occurs only when the posterior follicle cells are wild type for hop.
33

Management and nutrition of the replacement gilt.

Van Wettere, William January 2008 (has links)
Replacement gilts and early parity sows constitute a large, and increasing, proportion of modern breeding herds. Breeding herd profitability is therefore increasingly dependant on the efficiency of gilt management strategies as well as litter size at first farrowing; however, incidences of reproductive failures and small first litter sizes are common within cohorts of replacement gilts. Hence, this thesis had two primary aims which were addressed in four experiments; one, to identify whether the puberty stimulation and mating strategies developed for genotypes of 20 to 30 years ago are suitable for today’s heavier yet leaner genotypes; and two, to better understand the influence of pre-pubertal growth rate and metabolic status on reproductive maturation, puberty attainment and potential litter size. In experiment 1, 192 Large White/Landrace crossbred gilts were used to compare the effects on puberty attainment of commencing boar exposure at 161, 182 or 203 days of age, and the effect of first mating gilts at either the pubertal or second oestrus on ovulation rate and early embryo survival. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 22.8 ± 0.4 days after first mating (mean ± S.E.M), and the numbers of corpora lutea and viable embryos recorded. Delaying first boar contact until 182 or 203 days of age significantly (P < 0.01) reduced days-to puberty and increased the proportion of gilts attaining puberty within 10 days of start of boar exposure. Gilt age at mating had no effect on potential litter size; however, there was a tendency for gilts mated at their second oestrus to shed 0.6 more ova, and possess one more embryo at day 20 of pregnancy. Experiment 2 determined the effects of long- (chronic) and short- (acute) term moderate dietary restriction on ovarian development and oocyte developmental competence in 161- and 175- day old, pre-pubertal gilts. Both chronic and acute periods of moderate feed restriction reduced the number of medium follicles present on the ovaries of 161- and 175-day old gilts, as well as the proportion of oocytes reaching Metaphase II in vitro. However, feeding level during the 14 days prior to ovary collection had the greatest effect on follicular growth and oocyte quality. Experiments 3 and 4 investigated the effects of the same dietary treatments on the timing of puberty attainment in response to boar exposure and potential litter size following mating at the pubertal oestrus. Chronic dietary restriction during the pre-pubertal period delayed puberty attainment, but the timing of the pubertal response was unaffected by acute, moderate dietary restriction of previously well-fed gilts during the period immediately prior to, and coincident with, boar exposure. Acute dietary restriction or repletion stimulated an increase or decrease, respectively, in pubertal ovulation rates; however, neither the number of viable embryo present on day 22 of gestation nor embryo survival were affected by the nutritional treatments used in these studies. Overall, these results demonstrate that the timing and synchrony of puberty attainment is significantly improved when gilts first receive boar exposure at 182 days of age (or older). It is, therefore, concluded that sexual maturity, as measured by responsiveness to boar contact, occurs later in modern genotypes. It is also evident that within the age range investigated, delaying first mating until the second oestrus does not significantly increase either ovulation rate or embryo number at day 20 post-mating. Further, the current data provide the first evidence that despite profoundly affecting the size and morphology of the antral follicle pool as well as pubertal ovulation rates, subtle alterations in dietary intake have no affect on the number or proportion of embryos surviving the pre-and peri-implantation period. It is evident the litter size of gilts mated at the pubertal oestrus is not determined by the number of ova shed, with the current data demonstrating that increasing ovulation rates results in increased embryo mortality. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339082 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008
34

Mathematical modelling and experimental investigation of nutrient supply to the mammalian oocyte.

Clark, Alys Rachel January 2009 (has links)
The harvesting of immature mammalian oocytes (eggs) and their maturation in a laboratory environment, known as in-vitro maturation (IVM), provides an alternative to the harvesting of mature oocytes for in-vitro fertilisation (IVF) programs. The nutrient environment of an oocyte matured in vitro is known to have a significant effect on its potential to successfully mature, and it is desirable for the in-vitro nutrient environment to mimic the natural environment in vivo. This thesis describes an interaction between mathematical modelling and experimental investigation designed to build upon understanding of the nutrient environment of the oocyte in vivo, which is difficult to determine via experiment alone. A general mathematical model of nutrient transport to the oocyte, through its surrounding cumulus cells is developed. This model is applicable in-vivo and in-vitro across several species and to a number of important nutrients. Nutrient transport in this system - the cumulus-oocyte complex (COC) - is of particular importance, as it is this system that is normally removed for IVM treatments, and its solution under in-vivo conditions allows the nutrient concentration reaching the oocyte to be determined, given a known concentration immediately surrounding the COC. To successfully apply this model, parameters representing the rate of nutrient transport into cells within the COC must be accurately determined. These parameters are determined by a combination of experimental procedures and mathematical modelling in the case of an important nutrient to oocyte development, glucose. This work gives insight into the concentration dependence of glucose uptake into cell types that are important in regulating oocyte development, and to the behaviour of the oocyte itself with regard to glucose uptake. Finally models to describe the transport of two key nutrients, oxygen and glucose, from the vascular system in the ovary, through the ovarian follicle to the oocyte are developed. These make use of experimental results found in the study of glucose transport in the COC, and show that the geometry of the follicle has a significant impact on the nutrient environment of the COC, and hence by inference the nutrient environment of the oocyte. Work discussed in this thesis has been published [31, 156] and submitted for publication [30]. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1374636 / Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Science, 2009
35

The development and ultrastructure of intergeneric nuclear transfer embryos using ovine ooplasm.

Hamilton, Hamish MacDonald January 2005 (has links)
Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / This thesis encompasses work that aimed to further understand genomic reprogramming, an event crucial in obtaining development in cloned embryos produced by somatic cell nuclear transfer (SCNT). An increasing number of different mammalian species have been cloned using nuclear transfer technology since Dolly the cloned sheep was first successfully produced. However, the biological mechanisms involved in the process of nuclear reprogramming are yet to be fully described. At the centre of this study was an intergeneric SCNT model, which was implemented to determine whether reprogramming factors are conserved across genera. The interaction between donor nucleus and recipient ooplasm was characterised with regard to developmental potential, timing of genome activation, nucleolus formation, and expression of significant proteins. In initial studies, fusion parameters of the intergeneric SCNT procedure were optimised for the ovine cytoplast and porcine donor granulosa cell. Cell fusion and lysis percentages were determined over a range of electrical pulse voltage, duration and repetition. The optimal electrofusion settings were a single DC pulse of 1.5 kV/cm for 20 usec following a 2 sec 400 kHz alignment pulse. In addition, it was demonstrated that ovine oocytes were sensitive to electric stimulation to the extreme that oocyte activation would occur no matter how low the voltage. The practical significance was that it would not be possible to implement a fusion before activation protocol. The ability of the ooplasm of one species to replicate chromosomes and support early embryo cleavage was determined in a preliminary experiment where intergeneric embryos were produced by SCNT using bovine and ovine foetal fibroblasts, and ovine ooplasm. After their construction, the embryos were allowed to develop for 7 days in vitro and the developmental stage determined by Hoechst staining and nuclei counting. In addition, chromosome spreads of the ovine and bovine somatic foetal fibroblast cell lines used in SCNT, as well as the intra- and intergeneric SCNT embryos were prepared to determine whether the ovine ooplasm was replicating the chromosomes according to the karyotype of the donor nucleus. The somatic cells were karyotyped with 54 and 60 chromosomes counted for ovine and bovine cells respectively. Bovine-ovine embryos were characterised as having a bovine karyotype as distinct from an ovine karyotype, due to the presence of only two metacentric chromosomes as compared with six that are found in the latter. These preliminary results indicated that bovine nuclei obtained from foetal fibroblast cells could initiate early pre-implantation embryo development with the support of ovine oocyte cytoplasm. The development of a proportion (33%) of ovine-ovine intrageneric SCNT embryos beyond the 16-cell stage indicated that an extensive characterisation of an intergeneric model could be performed satisfactorily. It was hypothesised that the ovine ooplasm would possess the ability to direct in vitro preimplantation embryo development after nuclear transfer using donor nuclei from a different genus, as has been demonstrated in studies using bovine and rabbit ooplasm. In this study, intergeneric SCNT embryos were constructed by the separate fusion of porcine and bovine cells with ovine cytoplasts (bovine-ovine and porcine-ovine respectively), cultured in vitro and the developmental characteristics compared with ovine-ovine SeNT embryos as well as ovine in vitro produced (IVP) embryos. These four groups of embryos were sampled to determine embryo cell numbers at 24, 36, 48, 72, 96, 120 and 168 h post-activation to compare development over time. Despite cleaving normally and undergoing the first three cleavage divisions at a rate comparable with ovine-ovine SCNT embryos, a major block in development occurred in the intergeneric embryos at the 8-16 cell stage. Consequently, no blastocyst formation was obtained as observed for the IVP and ovine-ovine SCNT controls. These results indicate that unlike the rabbit and bovine ooplasm, the ovine ooplasm is not suitable for intergeneric reprogramming of somatic nuclei from another genus, at least of porcine or bovine origin. To determine the effect of a less differentiated donor nucleus on intergeneric developmental potential, embryonic cell nuclear transfer (ECNT) was conducted in a separate experiment by fusing pluripotent bovine and ovine donor cells (obtained from day-4 preimplantation embryos) to ovine cytoplasts. After 7 days of culture, the cell number of embryos was determined by Hoechst staining and fluorescent observation. Despite observing a single bovine-ovine blastocyst (4.8%), the developmental block remained at the 8-16 cell stage of development. This outcome indicates that a less differentiated nucleus does not increase intergeneric developmental capability. It is well documented that the ooplasm supplies a large amount of mRNA and protein to the newly formed embryo, crucial for normal development leading up to the major activation of the embryonic genome. However, the interaction between the ooplasm as compared with the donor nucleus in SCNT embryos during this developmental period is poorly understood. This intergeneric SCNT model provided an opportunity to determine the role of the ooplasm on nucleolus formation, which is a marker for genome activation. Ultrastructural evidence was obtained that indicates the ovine ooplasm directs the initial assembly of the nucleolus independent of the species of the nuclear donor. Intergeneric porcine-ovine SCNT and intrageneric ovine-ovine SCNT embryos were constructed and the nucleolus ultrastructure and nucleolus associated rRNA synthesis examined in 1-,2-,4-, early 8-, late 8-and 16-cell embryos using transmission electron microscopy (TEM) and light microscopical autoradiography. Intergeneric porcine-ovine SCNT embryos exhibited nucleolar precursor bodies (NPBs) of an ovine (ruminant) ultrastructure, but no active rRNA producing fibrillogranular nucleoli at any of the stages. Unusually, cytoplasmic organelles were located inside the nucleus of two porcineovine SCNT embryos. The ovine-ovine SCNT embryos, on the other hand, revealed fibrillogranular nucleoli in 16-cell embryos. In parallel, autoradiographic labelling over the nucleoplasm and, in particular, the nulcleoli was detected. Bovine-ovine SCNT embryos at the 8-cell stage were examined for nucleolar morphology and exhibited ruminant-type NPBs as well as structures that appeared to comprise of broken down fibrillar material, perhaps formerly of nucleolar origin from the donor cell. These observations indicate that factors within the ovine ooplasm are playing a role in the initial assembly of the embryonic nucleolus in intrageneric SCNT embryos. To further characterise nucleolus formation, immunocytochemical localisation by confocal microscopy of nucleolin, fibrillarin and RNA polymerase, three key proteins involved in processing rRNA transcripts, was performed on early 8-, late 8- and 16-cell embryos for ovineovine and porcine-ovine SCNT embryos. Nucleolin was localised throughout the nucleoplasm for all developmental stages examined in porcine-ovine and ovine-ovine SCNT embryos and, in particular, intensity around the presumptive nucleolar compartments in the later developmental stages. Fibrillarin and RNA polymerase I, on the other hand, were not detected in any ovineovine or porcine-ovine SCNT embryos or ovine IVP controls, although both proteins were detected in control bovine IVP blastocysts. This result indicates that the antifibrillarin and anti-RNA polymerase I were not compatible with the ovine form of these respective proteins. As nucleolin is not present in porcine in vivo embryos before the major activation of the embryonic genome, its presence in porcine-ovine SCNT embryo nucleus indicates that nucleolin is derived from the abundant protein and mRNA stored in the ovine ooplasm. The intergeneric SCNT model established in this thesis demonstrates that the ovine ooplasm lacks the ability to support embryonic development beyond the 16-cell stage. The TEM and autoradiographical studies, in combination with the protein immunocytochemistry study, confirmed that these embryos are unable to undergo the major activation of the embryonic genome, and that the ooplasm influences the initial nucleolar assembly in these embryos. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1167553 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2005
36

Efeito da suplementação de cisteína e cisteamina sobre a maturação nuclear de oócitos de fêmeas caninas (Canis familiaris) obtidos por ovariosalpingo-histerectomia durante a fase pré-ovulatória do estro /

Pires, Eliandra Antônia. January 2006 (has links)
Orientador: Wilter Ricardo Russiano Vicente / Banca: Maria Denise Lopes / Banca: Camila Infantosi Vannucchi / Resumo: O objetivo desta pesquisa foi avaliar os efeitos da suplementação de cisteína e cisteamina no desenvolvimento meiótico de oócitos caninos durante o processo de maturação ín vítro. Os oócitos foram coletados de sete cadelas hígidas em fase pré-ovulatória imediata, submetidas à ovario-histerectomia. Os COC's selecionados foram cultivados por um período de 72 horas em quatro meios diferentes: A (controle) - TCM199 suplementado com BSA (3 mg/mL) + FSH (5 J.Lg/mL) + LH (10 f.Lg/mL) + progesterona (2 f.Lg/mL) + estradiol (2 f.Lglml); 8 - controle + 0,1mM de cisteína; C - controle + 100J.1M de cisteamina; D - controle + 0,1 mM de cisteína + 100J.1M de cisteamina. Os resultados demonstraram que não houve diferença significativa entre os tratamentos (p<0,05), ou seja, a suplementação de compostos antioxidantes no meio de maturação não favoreceu a competência meiótica. Além disso, neste estudo pode-se inferir que para cada fase do ciclo estral, talvez seja necessário um período de maturação diferenciado. / Abstract: The aim of this research was to evaluate the effects of the cysteine and cysteamine supplementation on meiotic deveropment of canine oocytes dunng the process of in vitro maturation. The oocytes were collected atter ovanohysterectomy from seven healthy bitches in immediate preovulatory stage. The selected COC's were cultured by a period of 72 hours in four different media: A (control) - TCM199 supplemented with BSA (3 mg/mL) + FSH (5 J-Lg/mL) + LH (10 J-Lg/mL) + progesterone (2 f.Lg/mL) + estradiol (2 f.LglmL); 8 - control + 0,1mM of cysteine; C - control + 100JlM of cysteamine; O - control + 0,1 mM of cysteine + 100J,lM of cysteamine. The present study demonstrated that there was not significant difference among the treatments (p<0,05), in other words, the supplementation of antioxidant in the medium of maturation didn't favor the meiotic competence. Besides, in this study it can be inferred that for each stage of the oestrus cycle, perhaps it is necessary a different maturation penod. / Mestre
37

Impact of oocyte vitrification

Abdelsalam, Selima Mohamed January 2016 (has links)
Safe and effective oocyte cryopreservation will have a considerable impact on clinical practice in assisted reproduction. Great improvements have been made in recent years to oocyte vitrification procedures, although further controlled trials are necessary to ensure safety, and it is necessary to know more about pregnancy and live birth outcomes. This study aims to validate various methods of oocyte vitrification as assessed by comparative target gene analysis, hence contributing to information available to clinicians advising women about fertility preservation options before cancer treatment. Target genes investigated were: the maternal effect genes Deleted in Azoospermia Like (DAZL), Maternal Antigen That Embryos Require (MATER/NLRP5) and Zygote Arrest 1 (ZAR1); three genes involved in cell cycle progression and cell death, tumour suppressor protein 53 (p53), B-cell lymphoma 2 (BCL2), BCL2-Associated X Protein (BAX); three genes known to affect spindle and chromatin structure, oocyte-specific histone 1 (H1FOO), kinesin family member 11 (KIF11) and mitotic arrest deficient 2 (MAD2); together with Factor In the GermLine, Alpha (FIGLα) which regulates zona pellucida proteins, octamer-binding transcription factor 4 (OCT4/POU5F1) which is associated with pluripotency and oocyte developmental competence, and superoxide dismutase 2, mitochondrial (SOD2) which responds to oxidative stress in the mitochondria. These genes may be useful indicators of oocyte quality following vitrification. Lysis, complementary DNA (cDNA) amplification, polyadenylic acid polymerase chain reaction (polyA PCR) and quantitative polymerase chain reaction (QPCR) were used to investigate gene expression patterns in failed-to-fertilize non-vitrified, vitrified and slow frozen human MII oocytes. Comparative gene analyses included oocytes vitrified using closed and open carriers, and two different media. Results indicate that the impact of vitrification varies by gene and oocyte variability, highlighting the importance of studies based on single oocytes and the need for caution in interpretation of generalised findings. OCT4 and also β-actin were significantly affected by all methods investigated, while FIGLα, MAD2, ZAR1 and DAZL were affected by some methods. Oocyte survival rate after thawing and the number of genes expressed by individual oocytes were higher with media incorporating dimethyl sulfoxide (DMSO) and Dextran Serum Supplement (DSS) and first-step warming in a larger volume. All methods led to altered expression of target genes, most noticeably when the second media was used. Further quantitative studies of the impact of OCT4, FIGLα and β-actin should be conducted, together with clinical comparisons between media and a longitudinal multi-centre study regarding outcomes arising from different vitrification methods.
38

Development of Cell Volume Regulatory Mechanisms During Oocyte Growth and Meiotic Maturation

Richard, Samantha January 2017 (has links)
The ability of oocytes and early cleavage-stage embryos to regulate their volume is essential to avoid developmental arrests at in vivo-osmolarities. This is accomplished primarily via GLYT1-mediated glycine transport into the cells. GLYT1 activity has previously been shown to be absent in freshly isolated oocytes but becomes activated ~3-4 hours after oocyte maturation has been initiated either by isolation from ovarian follicles in vitro or following an ovulatory stimulus in vivo. GLYT1 activity then persists until the 4-cell stage of preimplantation embryo development. GLYT1 has been shown to spontaneously activate in oocytes that are isolated from follicles either as denuded oocytes or as cumulus-oocyte complexes (COCs), this implies that GLYT1 activity is suppressed in intact follicles in the ovary. However, it is not known how GLYT1 activity is suppressed within the ovarian follicle or how initial GLYT1 activation occurs. The activation of independent cell volume regulation in oocytes first involves the release of the strong adhesion between the oocyte and zona pellucida (ZP) followed by secondary GLYT1 activation. These two processes have been shown to occur spontaneously in fully grown oocytes following isolation from ovarian follicles, however, it is not known whether small growing oocytes within ovarian follicles already possess the ability to detach from the ZP and activate GLYT1. An osmotic assay was used to determine when during oogenesis oocytes are first able to detach from the ZP while the ability to activate GLYT1 was determined by measuring [3H]-glycine uptake into oocytes. I found that oocytes acquire the ability to detach from the ZP when they are nearly fully grown and similarly, that high levels of GLYT1 activity first develop in isolated oocytes during the late stages of oogenesis. Furthermore, I showed that SLC6A9 protein (GLYT1 transporter protein) and Slc6a9a transcripts steadily increased during oogenesis with SLC6A9 protein becoming localized to the oocyte plasma membrane during oocyte growth with predominant membrane localization apparent in fully grown oocytes. Taken together, these results suggest that oocytes become able to detach from the ZP and fully activate GLYT1 towards the end of oogenesis but that these processes remain suppressed in the ovarian follicle. Intact and punctured antral follicles were used as a model to examine the potential mechanism(s) mediating GLYT1 suppression before ovulation is triggered. Using these models, I found that GLYT1 activity remains suppressed within preovulatory antral follicles in contrast to the spontaneous GLYT1 activation that occurred in isolated denuded oocytes or within COCs. Recently, the mechanism mediating oocyte maintenance of prophase I arrest within the ovarian follicle was elucidated and was shown to depend on the release of Natriuretic Peptide Precursor C (NPPC) from mural granulosa cells (MGCs) into follicular fluid which binds to NPR2 guanylate cyclases on cumulus cells stimulating the production of cyclic GMP (cGMP) within these cells. Diffusion of cGMP from cumulus granulosa cells to the oocyte via gap junctions is required to maintain meiotic arrest. Although GLYT1 activation and meiotic resumption are both suppressed in antral follicles prior to the ovulatory trigger and these two processes occur simultaneously following oocyte isolation from ovaries, I have shown here that GLYT1 suppression within the preovulatory antral follicle is mediated by a mechanism distinct from the gap junction-dependent NPPC-cGMP pathway controlling meiotic arrest. I also showed for the first time a direct requirement for meiotic arrest of both gap junctions between granulosa cells (composed of connexin-43) and between the inner layer of cumulus granulosa cells and the oocyte (composed of connexin-37). Since I showed that GLYT1 was suppressed in isolated antral follicles but not COCs, I hypothesized that MGCs are required to maintain low GLYT1 activity in antral follicles. I showed here that MGCs isolated from preovulatory antral follicles were sufficient to maintain GLYT1 suppression in co-cultured COCs, but not denuded oocytes. Furthermore, I found that GLYT1 activity was suppressed in COCs cultured in conditioned medium from MGC cultures. Thus, GLYT1 activity appears to be suppressed within the ovary prior to the ovulatory LH-stimulus likely by an unidentified inhibitory signal within the ovarian follicle originating from the MGCs and propagated by a gap junction-independent mechanism involving multiple cell types in the follicle.
39

Improving referral rate of female cancer patients to reproductive endocrinology

Riemer, Rebecca 11 October 2019 (has links)
BACKGROUND: There are currently an estimated 250,000 female cancer survivors of reproductive age living in the US. Loss of fertility is an issue many cancer survivors face after treatment, as all forms of cancer therapy can cause infertility. Methods to preserve fertility can be initiated prior to cancer therapy. These methods include embryo cryopreservation, oocyte cryopreservation, fertility sparing surgery, ovarian tissue cryopreservation, ovarian transposition, and medical therapy. LITERATURE REVIEW: Although the clinical guidelines state that oncologists should discuss the risk of infertility with every patient of reproductive age and should refer every patient who is interested in or ambivalent towards fertility preservation to reproductive endocrinologists, studies have shown that a significant proportion of female cancer patients report never receiving information about fertility. Even fewer female cancer patients are referred to reproductive endocrinologists for further discussion and/or potential treatment. PROPOSED PROJECT: Oncologists at Boston Medical Center will be recruited to participate in a study that measures the effect of an educational intervention on referral rate to reproductive endocrinology. The knowledge gained from the intervention will be assessed with a pre- and post-test. The proportion of female patients age 18-45 referred to reproductive endocrinology will be evaluated through the Electronic Medical Record System. The correlation between knowledge gain and change in referral rates will also be assessed. CONCLUSION: Fertility after cancer treatment is an essential issue to consider for young cancer survivors. These patients benefit from being referred to reproductive endocrinologists so that they can get information about fertility preservation and undergo treatment in a timely fashion. Improving and/or reinforcing oncologist knowledge about this topic will increase the rate at which they initiate this conversation and therefore the number of female patients who are referred to reproductive endocrinology. SIGNIFICANCE: Providing female cancer patients with information about and opportunities to undergo fertility preservation will maximize their options. This will lead to a higher quality of life after cancer therapy.
40

Xenogenous Intrafallopian Transfer of Horse (Equus caballus) Gametes

Wirtu, Gemechu G. 27 August 1999 (has links)
This study was undertaken to evaluate fertilization and early embryo development of in vitro matured (IVM) horse oocytes following transfer with homologous sperm to the oviduct of estrous ewes. A total of 1023 follicles (5.1 per ovary) were found after processing 202 slaughterhouse ovaries by aspiration and subsequent slicing. Most follicles (79%) were less than 20-mm in diameter. Six hundred sixty-seven oocytes were recovered (3.3 per ovary; recovery rate, 65%). About two-thirds of oocytes were recovered by slicing, which yielded twice the number of oocytes as aspiration. Sixty four percent cumulus oocyte complexes (COCs) recovered by each method were grade A and the overall distribution of oocytes by grade was not affected by the method of recovery. Oocytes underwent IVM for an average of 41-h and were subjected to either in vitro fertilization (IVF) or xenogenous gamete intrafallopian transfer (XGIFT). At the onset of IVM, 83% COCs had compact cumulus investment. At the end of IVM, 78% COCs showed cumulus expansion. The expansion score was not improved with increasing the IVM duration from 32.3 to 50.3 h. Five (15%) IVF oocytes showed changes indicative of fertilization and two cleaved to 3 and 4-cell stages. Oviducts of 16 ewes were use for XGIFT, which involved surgical transfer of an average of 13 oocytes with 40x103 capacitated spermatozoa per oocyte. Of 259 oocytes transferred, 36 (14%) were recovered between 2 to 7 d post XGIFT and 13 (36%) showed cleavage ranging from the 2-cell to hatching blastocyst stage. The ovarian status of ewes and ligation of the uterotubal junction (UTJ) at the time of XGIFT, or the duration gametes were allowed to reside in the uterine tube, did not affect the recovery and cleavage rate. However, the most advanced stage embryos were recovered from ewes ovulating shortly after XGIFT. Fertilization following XGIFT was further demonstrated by the detection of ZFY loci in one embryo. This study demonstrated, for the first time, that horse embryos could be produced in a non-equine species. However, further studies focusing on the establishment of pregnancy in the mare using such embryos and improvement of the recovery and fertilization rates following XGIFT are recommended for use of XGIFT in horse assisted reproduction. / Master of Science

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