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Fertilized Sea Urchin Eggs as a Model for Detecting Cell Division Inhibitors
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Robert S. Jacobs, Leslie Wilson
The first of these “early events” (occurring within 20 sec after sperm-egg fusion) is a Ca2+-mediated fusion of the cortical granules with the plasma membrane. This exocytotic process releases colloidal material and peroxidase enzymes into the perivitelline space [19,20]. The enzymes released by the cortical granules then cause the vitelline layer to elevate the fertilization envelope (a now spherical membrane completely enclosing the zygote). This extracellular structure is subsequently “hardened” by ovoperoxidase-mediated phenolic coupling of tyrosyl residues present within the fertilization envelope proteins [21], Insertion of the cortical granule membranes into the egg plasma membranes during exocytosis results in the formation of a mosaic membrane [22,23], a process temporally associated with a change in conductance of the membrane to Na+ and H+.
Motility Parameters and Fertility
Published in Claude Gagnon, Controls of Sperm Motility, 2020
Fertilization of the mammalian ovum is an extremely specialized function for which the spermatozoon has evolved a strikingly complex architecture, enabling it to express a number of diverse properties including the potential for egg recognition, secretion of the acrosomal contents, fusion with the oocyte, and movement. The purpose of the latter is to bring the spermatozoa into close proximity with the egg and ultimately to achieve penetration of the investments surrounding the ovum which, in man, comprise a dense layer of cumulus cells and the zona pellucida. Once the spermatozoon has reached the perivitelline space, the need for movement is less apparent since completely immotile cells have been shown to fuse with the vitelline membrane of the oocyte.1
The embryonic period
Published in Frank J. Dye, Human Life Before Birth, 2019
We are now in the latter half of the first week (after fertilization) of development. The embryo is developing in its private fluid-filled space (perivitelline space), the boundary of which is the zona pellucida. Before the embryo can attach to the lining of the uterus (endometrium), it must hatch from the confines of the zona. This hatching is not very similar to a chick hatching out of its egg in which the egg shell is more or less broken into two pieces. During hatching of the blastocyst, a small opening is made in the zona by cells of the trophoblast, and the blastocyst squeezes out of its “shell” (Figure 8.4). This takes place on about the fifth or sixth day after fertilization.
Improvement of embryonic development and clinical outcomes of germinal vesicle stage oocytes using a microvibration culture system
Published in Systems Biology in Reproductive Medicine, 2019
Seong-Ho Yang, San-Hyun Yoon, Jae-Hoon Jung, Jin-Ho Lim, Yong Ko
The nuclear maturity of the retrieved oocytes was assessed using the dissecting microscope with high magnification (×80) using the sliding method (Chian et al. 2000). To exactly observe GV-stage oocytes, cumulus cells were partly removed using 25 IU hyaluronidase (MRC#hyase; Maria Fertility Hospital, Seoul, Korea) (Yoon et al. 2011) and mechanical pipetting. The GV-stage oocytes were transferred into an organ culture dish (60 × 15 mm, Falcon; Franklin Lakes, NJ, USA) containing 1 ml of IVM medium (YS medium; Maria Fertility Hospital, Seoul, Korea) (Yoon et al. 2001) supplemented with 30% of the patients’ own serum (inactivated at 56°C for 30 min) with a final concentration of 0.6 IU/ml recombinant human follicle-stimulating hormone (Gonal-F; Merck Serono, Geneva, Switzerland), 0.1 IU/ml HCG (LG), and 10 ng/ml recombinant human epidermal growth factor (Invitrogen, Seoul, Korea) at 37°C in 6% CO2, 5% O2, and 89% N2 with 95% humidity. After approximately 30 ~ 32 h of incubation in IVM medium, all COCs were denuded of the cumulus cells using 25 IU hyaluronidase and mechanical pipetting. Oocyte maturation was assessed by the presence of the first polar body in the perivitelline space.
Ultrastructural identification of CD9 positive extracellular vesicles released from human embryos and transported through the zona pellucida
Published in Systems Biology in Reproductive Medicine, 2019
Parshvi Vyas, Hanna Balakier, Clifford L. Librach
There is growing evidence for the possible role of EVs, particularly exosomes, in key reproductive processes including follicular growth, oocyte and sperm maturation, fertilization, embryo implantation, as well as in pre-term labour and pre-eclampsia (Di Pietro 2016; Machtinger et al. 2016; Marin and Scott 2018; Martinez et al. 2018). The fusion of oocyte and sperm during fertilization in mice has been shown to be dependent on the release of CD9 positive vesicles by oocytes into the perivitelline space (PVS) where they bind to sperm promoting fertilization (Miyado et al. 2008). Additionally, CD81 associated vesicles have been reported to be expressed on the surface of mouse oocytes and granulosa cells, and possibly participate in gamete fusion by mediating the sperm acrosome reaction (Tanigawa et al. 2008). In addition, recently it has been shown that EVs containing the Juno protein appear to be shed by oocytes into the perivitelline space and may play a role in preventing polyspermy (Bianchi and Wright 2014; Machtinger et al. 2016).
Toxicity assessment of biological suspensions using the dielectric impedance spectroscopy technique
Published in International Journal of Radiation Biology, 2018
S. Muñoz, J. L. Sebastián, P. Antoranz, J. P. García-Cambero, A. Sanchis-Otero
To determine the electrical parameters of the suspension across the full frequency band, we have used Comsol (Comsol Multiphysics®, Los Angeles, CA) that implements the FE numerical technique to calculate the complex impedance of the simulated test fixture filled with the sample. To model the suspension a simplified spherical four-layer geometry has been used for the embryos, according to their main compartments: the chorion, the perivitelline space, the yolk membrane and the inner part – composed by the animal and the vegetal poles-. Table 1 shows the geometrical dimensions observed for those compartments and their electrical parameter values, calculated from the polarizability obtained through electrorotational measurements for the same embryo dimensions and egg water characteristics (Sanchis et al. 2017). In that study, Sanchis et al. adopted a simplified spherical equivalent homogeneous model for the embryo and the dielectric properties of the medaka fish embryo (Shirakashi et al. 2012) were used as reference values for the dielectric characterization of the zebrafish embryo model. Later, we attempt to check the validity of these parameters by calculation of the polarizability of the four-shelled embryo model using the FE method. We noted that the frequency range coincides with the operating frequency range of the rotating field generator used in the experiments.