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Blastocysts

The blastocyst is an early embryonic stage in mammalian development. Murine blastocysts can be harvested at day 3.5 p.c. Their inner cell mass contains embryonic stem cells. Multiple murine embryonic stem cell lines have been established. Embryonic stem cells carrying genetically engineered mutations are injected into blastocysts, which are subsequently implanted into pseudopregnant foster mothers. [Pg.272]

Reik We have no direct evidence for a demethylase of any kind. It is just an activity that we observe here. We know that after this rapid demethylation, there is also passive demethylation, which is replication-dependent. You could ask whether this whole process is a bit of a waste. Why do you want to demethylate your paternal genome at fertilization if you also demethylate the rest of the genome at the blastocyst stage ... [Pg.33]

Kubiak No, the majority of maternal mRNA is only degraded before the second mitosis. There are some mRNAs, however, that persist until the blastocyst stage. [Pg.90]

Carayannopoulos, M. O., et al. GLUT8 is a glucose transporter responsible for insulin-stimulated glucose uptake in the blastocyst. Proc. Natl. Acad. Sci. U. S. A. 2000, 97, 7313-7318. [Pg.282]

Gonadotrophins are also used in assisted reproduction procedures. Here the aim is to administer therapeutic doses of FSH that exceed individual follicular FSH threshold requirements, thus stimulating multiple follicular growth. This, in turn, facilitates harvest of multiple eggs, which are then available for in vitro fertilization. This technique is often employed when a woman has a blocked fallopian tube or some other impediment to normal fertilization of the egg by a sperm cell. After treatment, the resultant eggs are collected, incubated in vitro with her partner s sperm, incubated in culture media until the embryonic blastocyst is formed, and then implanted into the mother s uterus. [Pg.320]

Embryonic stem cells are derived from pre-implant-stage human embryos, usually at the blastocyst stage (the blastocyst is a thin-walled hollow structure containing a cluster of cells, known as the inner cell mass, from which the embryo arises). These embryos are invariably ones initially generated as part of in vitro fertilization procedures but which are destined to be discarded, either due to poor quality or because they are in excess to requirement. There are an estimated 400 000 in vitro fertilization-produced embryos in frozen storage in the USA alone, of which some 2.8 per cent are likely to be discarded. [Pg.457]

Culture of human embryonic stem cells starts with the recovery of the blastocyst s inner cell mass (Figure 14.17). One common recovery procedure is termed immunosurgery . The process... [Pg.457]

Blastocyst The mammalian embryo in the post-morula stage in which a fluid-filled cavity, enclosed primarily by trophoblast, contains an inner cell mass which becomes the embryonic disc. [NIH]... [Pg.62]

Conception The onset of pregnancy, marked by implantation of the blastocyst the formation of a viable zygote. [EU]... [Pg.64]

After about 5 days and several cycles of cell division, the totipotent cells form a hollow sphere of cells called a blastocyst. The blastocyst has an outer layer of cells surrounding clusters of cells. Those cells on the outside continue... [Pg.126]

There are two general avenues for stem cell research pluripotent and multipotent stem cells. Pluripotent stem cells are obtained by two methods. One method is to harvest the clusters of cells from the blastocysts of human embryos. Another method is the isolation of pluripotent cells from fetuses in terminated pregnancies. Multipotent stem cells are derived from umbihcal cords or adult... [Pg.127]

The ESC of hamsters, rabbits, sheep, pigs, cattle, and primates are obtained from three embryonic layers, these are ectoderm, endoderm and mesoderm. The lines of murine permanent ESC are known. J. A. Thompson et al. (1996-1998) obtained several lines of permanent ESC of human from internal cellular mass (ICM) of blastocyst. [Pg.217]

Embryonic stem cell lines derived from hrnnan blastocysts. Science 1998 282 1145 7. Thomson, J.A. et al. Isolation of a primate embryonic stem cell line. Proc.Nad. Acad. Sci. USA 92, 7844-7844 (1995). [Pg.222]

Provided these two processes are in phase, the conditions are then optimal for fertilisation, proliferation of the zygote to form the blastocyst, implantation of the latter and maintenance of pregnancy. Before ovulation, the development of the ovum and hormone secretion take place in a single structure, the follicle. [Pg.433]

In the human, the uterus lies like an inverted pear in the pelvis. The wall of the uterus consists of three layers a thin outer layer, the perimetrium a middle muscular layer, the myometrium and an inner glandular mucosa, the endometrium, which lines the uterine cavity. Once the ovum is fertilised, the zygote undergoes several cell cycles (Chapter 20) to form a rounded mass of cells, the blastocyst, which passes into the uterus where it implants in the wall (see below). [Pg.434]

If fertilisation does not occur, the corpus luteum regresses and the levels of oestrogen and progesterone fall. However, if fertilisation does occur, the corpus luteum is maintained. Regression of the corpus luteum is prevented by the implanting blastocyst which secretes a hormone, human chorionic gonadotrophin (hCG). This occurs about a week after fertilisation. The structure of this hormone is similar to that of LH and it takes on the role of LH in maintenance of the corpus luteum. To do this, it binds to the LH receptor... [Pg.444]


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