Unfertilized Oocytes (unfertilized + oocyte)

Distribution by Scientific Domains

Selected Abstracts

Infertility observed in female rats treated with N-acetyl-L-cysteine: Histopathological examination of ovarian follicles and recovery of fertility

Miwa Harada
ABSTRACT, We previously reported infertility in female rats that received N,acetyl-L-cysteine (NAC) intravenously at a dosage of 1000 mg/kg/day. Unfertilized oocytes and gestation day 1 and 2 embryos were assessed morphologically, and the results suggested that absence or thinning of the zona pellucida (ZP) is related to infertility. However, the morphological characteristics of oocytes before ovulation and recovery from the effects of NAC were not clarified. In the present study, the ovarian follicles were histopathologi,cally examined and the recovery of reproductive function was evaluated to investigate the effects of NAC. Female Sprague-Dawley rats at 10 weeks of age received NAC intravenously at 1000 mg/kg/day for more than 1 week. Thinning of the ZP was observed in the ovarian follicles in all stages of growth by light microscopy. Outflow of the components of the ZP between the corona radiata and disarrangement of the corona radiata were more pronounced in growing follicles than in large secondary follicles. Similar findings were observed by electron microscopy, and the effects of NAC were limited to the ZP. Infertility and thinning of the ZP were observed in the no,recovery NAC group, but not in the recovery NAC group, in which animals recovered within four estrous cycles after NAC administration. It has been reported that the ZP is expressed by oocytes or by both oocytes and granulosa cells, but no changes were noted in these cells. The present findings suggest that NAC affects the ZP directly and that reproductive function may recover from the effects of NAC. [source]

Early ontogeny and placentation of the grey short-tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotype

This study provides new findings on the placenta of Monodelphis domestica and a reconstruction of the marsupial morphotype. To achieve this, early ontogeny and placentation of the grey short-tailed opossum, M. domestica, from 3 h after copulation until birth (day 15), were studied and compared with other mammals. Both the ultrastructure and histochemistry of egg membranes, foetal membranes, oviduct and uterus were examined. The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial. In addition, this is the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. These findings were compared with literature data and included into the reconstruction of the marsupial morphotype. Based on marsupial phylogeny as proposed by Luckett (J. Mammal. Evol. 2, 255,283, 1994), characters that are consistent at least within didelphids and dasyurids were determined to be characters of the marsupial morphotype. These characters are a central yolk separated from the peripheral yolk-poor cytoplasm in the unfertilized oocyte, the presence of a zona pellucida, a mucoid coat and a shell coat, the absence of a corona radiata, oviductal mucoid secretion, no shell secretion distal to the isthmus of the oviduct, uterine shell secretion, a short tubal passage (1 day at maximum), the apposition of blastomeres to the zona pellucida prior to intercellular association, the absence of a morula stage, the polarity of the zygotic yolk, the localized segmentation of deutoplasm (yolk) during the first cleavage and subsequent extrusion of yolk vesicles during the first two cleavage stages. With regard to the marsupial morphotype, the non-polarized yolk distribution in the zygote [Hartman (J. Morphol. 27, 1,84, 1916); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] is a derived character of Didelphis virginiana. Didelphis virginiana [Hartman (J. Morphol. 27, 1,84, 1916); Hartman (J. Morphol. 32, 1,139, 1919); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] and Didelphis marsupialis (Hill, Q. J. Micr. Sci. 63, 91,139, 1918) share the synapomorphous reduction of deutoplasmolysis to a generalized extrusion of vesicles. The absence of separated yolk and consequently a cleavage without yolk extrusion (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996) are apomorphies of macropodids. This is possibly correlated with the association of blastomeres in early cleavage stages (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996). A yolk sac placenta and a vascularized allantochorion can be assumed for part of the ontogeny in the marsupial morphotype, irrespective of the formation of an allantoic placenta at near term stages. The character polarization of the mode of placentation and parturition needs further investigation. Frühe Ontogenie und Plazentation der grauen Hausspitzmausbeutelratte, Monodelphis domestica (Didelphidae: Marsupialia): Ein Beitrag zur Rekonstruktion des Grundplans der Marsupialia Die vorliegende Arbeit beschreibt die frühe Ontogenese und Plazentation von 3 Stunden nach der Kopulation bis zur Geburt der Beutelratte Monodelphis domestica. Es wird die Ultrastruktur und Histochemie der Eihäute, der Fetalmembranen, des Oviductes und des Uterus beschrieben. Erstmalig wird die Ultrastruktur eines trophoblastischen Syncytiums bei einem Beuteltier beschrieben. Weiterhin wird ein invasives Trophektoderm und eine Entzündungsreaktion zum Zeitpunkt der Geburt bei M. domestica festgestellt. Die Befunde dieser Studie und Literaturdaten werden verglichen und in eine Grundplanrekonstruktion integriert. Merkmale, die mindestens zwischen Vertretern der Didelphidae und Dasyuridae übereinstimmen, werden basierend auf dem phylogenetischen System der Marsupialia nach Luckett, J. Mammal. Evol. 2, 255,283, 1994, für den Grundplan der Marsupialia angenommen. Diese Merkmale sind zentral separierter Dotter und peripheres dotterarmes Zytoplasma in der unbefruchteten Eizelle, das Vorhandensein von Zona pellucida, Mucoidschicht und Schalenhaut, das Fehlen einer Corona radiata, die Mucoidsekretion durch den Oviduct, die Schalensekretion durch den Uterus und nicht distal der Isthmusregion des Oviductes, eine kurze Tubenwanderung (maximal einen Tag), die Anlagerung der Blastomeren an die Zona pellucida vor der interzellulären Verbindung, das Fehlen eines Morulastadiums, die Dotterpolarität in der Zygote, die lokale Dotterabtrennung bei der ersten Teilung und die anschließende Dotterextrusion während der ersten beiden Teilungen. In Bezug auf den Grundplan der Marsupialia ist die unpolare Dotterverteilung in der Zygote ein abgeleitetes Merkmal von Didelphis virginiana. Didelphis virginiana und Didelphis marsupialis teilen als Synapomorphie die Reduktion der Deutoplasmolyse auf eine generelle Vesikelextrusion. Das Fehlen separierten Dotters in der Oocyte und die resultierende Furchung ohne Dotterextrusion [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996] ist eine Apomorphie der Macropodidae. Hiermit hängt möglicherweise die frühe Zusammenlagerung der Blastomeren zusammen [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996]. Ein vaskularisiertes Allantochorion und eine Dottersackplazenta können für einen Teil der Ontogenese im Grundplan der Marsupialia angenommen werden. Ob das Allantochorion neben der Respiration auch dem Stoffaustausch diente ist unklar. Die Lesrichtung für den Modus der Plazentation und der Geburt bedarf weiterer Untersuchungen. [source]

Embryotropic effect of insulin-like growth factor (IGF)-I and its receptor on development of porcine preimplantation embryos produced by in vitro fertilization and somatic cell nuclear transfer

Sue Kim
Abstract Insulin-like growth factor (IGF)-I is a receptor-mediated autocrine/paracrine growth/survival factor for mammalian embryo development. The present study investigated the temporal expression and regulation of porcine IGF-I receptor (IGF-IR) mRNA and the role of IGF-I on development of porcine in vitro fertilized (IVF) and somatic cell nuclear transfer (SCNT) embryos. As assessed by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), the level of IGF-IR mRNA expression was high in unfertilized oocytes, 2-cell and 4-cell embryos and gradually decreased in 8-cell embryos, morulae, and blastocysts in both IVF and SCNT series. The IVF or SCNT embryos were cultured with 0, 1, 10, 50, or 100 ng/ml IGF-I for 168 hr. Supplementing with 50 ng/ml IGF-I increased blastocyst formation and the number of cells in inner cell masses (ICMs) in both IVF and SCNT embryos. In a second experiment, more blastocysts were obtained when IVF or SCNT embryos were cultured for the first 48 hr or for the entire 168 hr with 50 ng/ml IGF-I compared to culturing without IGF-I for 48 hr or with IGF-I for the last 120 hr or without IGF-I for the entire 168 hr. Treating IVF or SCNT embryos with 50 ng/ml IGF-I significantly up-regulated IGF-IR mRNA compared to untreated control embryos. In conclusion, the present study demonstrated that IGF-IR mRNA is expressed in porcine IVF and SCNT embryos, and that IGF-I improved the developmental competence of IVF and SCNT embryos through its specific receptors. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source]

Use of microbeads for the detection of binding sites on the human zona pellucida: a scanning electron microscopy (SEM) assay

ANDROLOGIA, Issue 5 2001
Prof. Dr H. W. Michelmann
Summary One prerequisite for fertilization is the specific binding of spermatozoa to the zona pellucida. However, the factors and mechanisms involved in this gamete contact are not well understood. Gamete recognition and binding are species-specific and are controlled by oligosaccharides of the zona and their corresponding carbohydrates on the spermatozoon. By using a specific lectin we developed a technique to detect those oligosaccharides on the human zona pellucida that might be involved in the binding process. Microbeads (Ø = 2.8 ,m), used as artificial spermatozoa, were coated with lectin Con A and cultured together with 75 unfertilized oocytes (group A) remaining after intracytoplasmic sperm injection. Con A binds specifically to ,-D-mannose and ,-D-glucose. As a control, 75 unfertilized oocytes after intracytoplasmic sperm injection (group B) were also cultured together with Con A-covered microbeads, but in a medium containing a binding inhibiting sugar (,-methyl-mannopyrasosid). The number and distribution of the microbeads on human oocytes of both groups were analysed on scanning electron microscopy images. Beads on oocytes of group A had binding patterns similar to those of spermatozoa. They were distributed in an extremely heterogeneous way with various numbers of bound beads both on individual and different oocytes. Most of the group A oocytes (85%) had more than 50 beads bound to the zona, in contrast to the control oocytes of group B, where 68% had less than 10 bound beads. The use of an inhibiting sugar abolished the binding capacity of the microbeads nearly completely. This technique is a powerful tool for the detection of binding sites on the zona pellucida, i.e. those sugars that are responsible for contact between spermatozoa and the zona pellucida. [source]