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Fertilization and normal embryonic and early fetal development
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Asim Kurjak, Ritsuko K. Pooh, Aida Salihagic-Kadic, Iva Lausin, Lara Spalldi-Barisic
A series of mitotic divisions lead to the development of the pre-embryo. The newly divided cells are called blastomeres. 24 hours after fertilization from single-cell zygote two-celled embryo is developed. 2 days after the fertilization embryo consists of 6 to 8 blastomeres. Blastomeres form cellular aggregates of distinct, totipotent, undifferentiated cells that retain the capacity to develop independently into normal pre-embryos. After every division, blastomeres become half of their previous size keeping the total size the same as in the beginning when it was just one cell. All up to eight-cell phase, blastomeres are cluster of cells inside the zona pellucida. But after the third division, they lose their round shape and they impact one to the other making compact round cluster of cells that are tightly connected by tight junctions. With that change, which is called compaction, cells from the outside start to differentiate from those inside. Third day after the fertilization, cells of the compact embryo divide again and morula arises. It contains 16 cells, outer part from which trophoblast will appear and inner cells from which embryo will appear.
Ectopic Pregnancy and Pregnancy of Unknown Location
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
Abnormalities of the tubal morphology and/or changes in the tubal microenvironment resulting from damage to the tubal mucosa and/or disturbance to tubal muscular contractility due to tubal inflammation have been implicated in impairing migration of the fertilized ovum and halting it within the fallopian tube, permitting early implantation and leading to delay in embryo transfer and incorrect signaling, resulting in abnormal implantation. It has also been suggested that an altered estrogen/progesterone ratio can cause malfunction of the tubal smooth muscle [8–13]. The etiology behind ectopic pregnancy in the absence of any tubal factors remains unclear. Poor quality of the morula or a chromosomally abnormal pregnancy have been suggested [14]. However, Goddijn et al. showed in his study that the rate of chromosomally abnormal ectopic pregnancies is not higher than intrauterine pregnancies [15]. The effect of the male factor has also been suggested in the pathophysiology behind ectopic pregnancies, but more studies are needed to confirm this.
Regulation of Reproduction by Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
After fertilization, the zygote undergoes several mitotic divisions and forms a solid ball, the morula, which travels down the oviduct toward the uterus (Figure 10.15). Upon reaching the 20–30 cell stage, the morula starts a process of differentiation and cavitation to form a blastocyst. The blastocyst, still surrounded by the ZP, is composed of three regions: (1) an inner cell mass, which will develop into the embryo; (2) a surrounding outer layer called the trophoblast, which will develop into the placenta; and (3) a fluid-filled cavity called the blastocoele. DA-producing pluripotent cells isolated from the inner cell mass of preimplantation monkey blastocysts provided evidence for a very early expression of DA, even before implantation [84]. Yet, what functions are fulfilled by this DA in implantation and/or in growth of the embryo, remain to be determined.
Modulating the lipid profile of blastocyst cell membrane with DPPC multilamellar vesicles
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2022
Hugo De Rossi, Camila Bortoliero Costa, Luana Teixeira Rodrigues-Rossi, Giovana Barros Nunes, Dóris Spinosa Chéles, Isabella Maran Pereira, Daniele F. O. Rocha, Eloi Feitosa, Ana Valéria Colnaghi Simionato, Gisele Zoccal Mingoti, Pedro Henrique Benites Aoki, Marcelo Fábio Gouveia Nogueira
It is likely that the conditions of the co-cultivation of MLVs with embryos induced a dynamic change in the average diameter of the vesicles with the rupture of outer bilayers or the fusion of them (decreasing and increasing the diameter, respectively). MLVs with a decreased diameter (the inner core) could pass through the pores of the zona pellucida and reach the embryonic cells. In this theoretical scenario, lipid exchange could occur via direct action, i.e. by the fusion of MLVs and/or lipid bilayers with embryos [50,51] and/or indirect action, i.e. by inducing an endogenous change in lipid metabolism [52,53]. Vanroose et al. [54] found a difference in the quantity and diameter of the outer pores of the zona pellucida according to the embryonic developmental stage. Although the blastocyst stage was not evaluated by Vanroose et al. [54], the development of the morula (which was predicted at D5 of the IVC in our study) was analysed. At this stage (morula), the average outer pore diameter was 155 nm, and 19% of the pores were larger than 200 nm [54].
Differences in secretome in culture media when comparing blastocysts and arrested embryos using multiplex proximity assay
Published in Upsala Journal of Medical Sciences, 2018
Karin E. Lindgren, Fatma Gülen Yaldir, Julius Hreinsson, Jan Holte, Karin Kårehed, Inger Sundström-Poromaa, Helena Kaihola, Helena Åkerud
The most commonly used technique for selecting embryos for transfer is based on embryo morphology (2), where timing of development is studied. This is, however, a non-standardized method and limited due to inter-individual variability, since evaluation of morphology is performed manually. In previous studies, the impact of using time-lapse photography has been shown to correlate well with increased success rates after IVF treatment (48). Timing to morula formation has been shown to be crucial for the ability of the embryo to develop into a blastocyst (24), and our results are in agreement with this. We also conclude that timing to morula formation is of major importance as regards the formation of high-quality blastocysts. We also showed that the levels of protein expression and time to morula formation were significantly correlated. The protein levels of VEGF-A, IL-6, and EMMPRIN were significantly higher in the embryos that had a shorter time to morula formation.
Prenatal Sonographic Detection of Monochorionic Twins with Bipartite Placenta
Published in Fetal and Pediatric Pathology, 2021
Mehmet Serdar Kutuk, Taha Takmaz, Arslan Bayram, Sule Ozturk
The mechanism of bipartite placenta is explained by three theories. The first advocates the failure of decidua capsularis to regress, persisting as a succenturiate or bipartite placenta [8]. The second theory suggests insufficient nutrition in the placenta and migration of some part of it to distant, more suitable areas as an underlying cause [9]. The third theory explains the partition of the placenta based on rhesus placentation. According to this scenario, the morula implants itself on the two adjacent walls of the uterus in the early embryonic period; as the uterus grows and changes its three dimensional geometry, it pulls apart the separate part of the placenta [10].