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The context of birth
Published in Helen Baston, Midwifery, 2020
Each month of the menstrual cycle an egg is released from the ovary into the fallopian tube. Following sexual intercourse, sperm migrate from the vagina, through the cervix into the uterus and swim up the fallopian tubes. When one sperm penetrates the egg, the gametes unite, and the egg is fertilised and becomes a solid ball of rapidly dividing cells (morula) and continues down the fallopian tube into the uterus where it embeds. It is called a blastocyst when it becomes a hollow ball of cells which is one-cell thick, except in one area which is thicker. The cells nearest the lumen of the blastocyst become the embryo and those nearer the outer wall, the trophoblast, become the placenta. The trophoblast further differentiates into an outer membrane known as the chorion, which surrounds the blastocyst, and an inner membrane known as the amnion, which develops into the amniotic sac. The sac begins to fill with amniotic fluid which the developing embryo floats in. The developing placenta starts to produce a hormone called human chorionic gonadotrophin (hCG) which acts on the ovaries preventing further ovulation and stimulating the production of oestrogen and progesterone and maintenance of the corpus luteum. Oestrogen and progesterone are also produced from the developing placenta and levels are adequate by 5–6 weeks, from which time production from the corpus decreases.
Oxidative stress and pre-eclampsia
Published in Pankaj Desai, Pre-eclampsia, 2020
Trophoblasts seem to be a specialized cell lining. At the first step or first wave, they have a critical anchoring role. The first wave of trophoblastic invasion anchors the placenta with the maternal surface. This occurs early in pregnancy. It may be as early as 1 week and may get completed by the fourth week of pregnancy. Near simultaneously, another amazing phenomenon is occurring: This is the second wave of trophoblastic invasion. The second wave of trophoblastic invasion has an extremely specialised function. It is confined to the maternal spiral arterioles in the uterine vasculature. These trophoblasts mould and modify the spiral arterioles in such a way that the latter get shielded off from maternal circulation. As a result, circulating compounds in the maternal circulation, which can alter the calibre of the vessels, are rendered ineffective to generate this altering effect on foetal vasculature. At the same time, they also destroy the muscular wall of the spiral arterioles. This makes the foetoplacental interface, a low-resistance pool of circulation. It seems that there may be Hypoxia Inducible Factor (HIF) that directly alters the cellular responses to low oxygen, which in turn influences the trophoblast lineage commitment and thereby promotes the development of the invasive trophoblast lineage.37
The Immunological Approach To the Treatment of Human Recurrent Spontaneous Abortion by Immunization with Lymphocytes
Published in Gérard Chaouat, The Immunology of the Fetus, 2020
J. L. Underwood, J. F. Mowbray
A number of workers have shown that the human trophoblast does not express classical Class I or Class II MHC antigens.7,8 The trophoblast is the tissue which in early pregnancy envelops the embryo and in later pregnancy is the outer covering of the placenta. Thus it is the tissue in intimate contact with the maternal circulation and tissues and, as such, acts as a protective barrier between fetus and mother. The lack of paternal antigens on the trophoblast prevents the mother seeing the fetus as a semiallogeneic graft, generating, perhaps, cytotoxic T-cells which could attack the trophoblast cells if they were expressing foreign antigens.
YKL-40 promotes proliferation and invasion of HTR-8/SVneo cells by activating akt/MMP9 signalling in placenta accreta spectrum disorders
Published in Journal of Obstetrics and Gynaecology, 2023
Weifang Liu, Runfang Wang, Suxin Liu, Xiaoqian Yin, Yan Huo, Ruiling Zhang, Jia Li
Placenta accreta spectrum (PAS) is the abnormal attachment and invasion of the chorionic villi in the myometrium. Pathologically, it can be classified into three categories: placenta accreta, increta, and percreta (Jauniaux et al. 2018). A recent study showed that the overall rate of PAS in the United States was 3.7‰ delivery-related discharges (Mogos et al. 2016). The primary cause of PAS is caesarean delivery. In recent years, the incidence of placenta previa and PAS has increased dramatically with the increase in caesarean delivery rates. In addition, postpartum haemorrhage and obstetric hysterectomy have increased rapidly due to the occurrence of placenta accreta and placenta previa (Pan et al. 2015, Weiniger 2020, OğlakÖlmez and Tunç 2022). The pathogenesis of PAS could be attributed to the defects in uterine metaplasm, excessive invasion of extravillous trophoblast cells, and abnormal angiogenesis (Long et al. 2020). Moreover, the proliferation, invasion and migration of trophoblast cells was similar to tumour cells (Zhang et al. 2020). Hence, further exploration of the pathogenesis of abnormal trophoblast invasion in PAS will provide more help for the diagnosis and treatment of PAS in the clinic.
Silver nanoparticles suppress forskolin-induced syncytialization in BeWo cells
Published in Nanotoxicology, 2022
Yuji Sakahashi, Kazuma Higashisaka, Ryo Isaka, Rina Izutani, Jiwon Seo, Atsushi Furuta, Akemi Yamaki-Ushijima, Hirofumi Tsujino, Yuya Haga, Akitoshi Nakashima, Yasuo Tsutsumi
Next, we assessed the effect of nAg10 on cell–cell fusion progression. Syncytin-1 (gene name; ERVW-1 [endogenous retrovirus group W member 1]) and Syncytin-2 (gene name; ERVFRD-1 [endogenous retrovirus group FRD member 1]) play important roles in cell–cell fusion during the trophoblast syncytialization process. Syncytin-2 controls the process by which single mononuclear cells fuze with each other and Syncytin-1 promotes the fusion of formed multinuclear syncytiotrophoblast cells with mononuclear cells (Nakamura and Imakawa 2011; Lavialle et al. 2013). Real-time RT-PCR analysis showed that, when either nAg10 (Figure 4(a)) or nAu10 (Figure 4(b)) were added, there was no significant change in the forskolin-induced upregulation of ERVW-1 mRNA. In contrast, the ERVFRD-1 mRNA level declined significantly when nAg10 (0.078 and 0.156 µg/mL) (Figure 4(c)) was added to forskolin-treated cells, but not when nAu10 (Figure 4(d)) was added. These results suggest that nAg10 decreased the expression of ERVFRD-1 for trophoblast cell fusion, thus suppressing the formation of the syncytiotrophoblast.
Uptake of antiepileptic drugs in forskolin-induced differentiated BeWo cells: alteration of gabapentin transport
Published in Xenobiotica, 2022
Mai Koishikawa, Ayako Furugen, Nanami Ohyama, Katsuya Narumi, Shuhei Ishikawa, Masaki Kobayashi
In placental villi, nutrients, drugs, and waste products are exchanged between the mother and the foetus. On the villous surface, mononuclear cytotrophoblast cells (CT cells) are the predominant cells present in early pregnancy, and these cells differentiate into multinuclear syncytiotrophoblast cells (ST cells) as pregnancy progresses (Tetro et al. 2018). Both morphological and biochemical changes have been observed during the differentiation of CT cells into ST cells. For example, human chorionic gonadotropin (hCG) secretion and syncytin-1 expression increase during differentiation. hCG, a hormone produced during pregnancy, promotes progesterone production from the luteum, the fusion of CT cells, and their differentiation into ST cells (Cole 2010). Syncytin-1 (HERV-W) is an endogenous retrovirus envelope protein that plays a role in the membrane fusion of CT cells (Bastida-Ruiz et al. 2016). hCG and syncytin-1 are widely employed as markers of trophoblast differentiation. It has been observed that the differentiation of CT cells into ST cells can be reproduced in vitro by isolating and culturing CT cells from the human placenta (Kliman et al. 1986). Primary human trophoblast cells have the advantage of retaining the property of normal cells. Conversely, the experimental procedure is complicated, and the obtained primary human trophoblast cells possess a low proliferation capacity. Therefore, as an alternative, the human placental choriocarcinoma cell line, BeWo cells, can be induced to differentiate into ST-like cells by stimulation with forskolin, an adenylate cyclase activator (Rothbauer et al. 2017).