Structure formed around day 5 of mammalian embryonic development
For the non-species-specific developmental stage, see Blastula. For the single-celled parasite, see Blastocystis.
Blastocyst
Blastocyst just before implantation
A human blastocyst, with inner cell mass at upper right
Details
Carnegie stage
3
Days
5–9
Gives rise to
Gastrula
Identifiers
Latin
blastocystis
MeSH
D001755
TE
E2.0.1.2.0.0.12
FMA
83041
Anatomical terminology
[edit on Wikidata]
The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the embryoblast which subsequently forms the embryo, and an outer layer of trophoblast cells called the trophectoderm.[1][2] This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoel.[3] In the late blastocyst, the trophectoderm is known as the trophoblast.[2] The trophoblast gives rise to the chorion and amnion, the two fetal membranes that surround the embryo. The placenta derives from the embryonic chorion (the portion of the chorion that develops villi) and the underlying uterine tissue of the mother.[4][5]
The name "blastocyst" arises from the Greek βλαστόςblastós ("a sprout") and κύστιςkýstis ("bladder, capsule").
In non-mammalian animals, this is a structure consisting of an undifferentiated ball of cells and is called a blastula.
In humans, blastocyst formation begins about five days after fertilization when a fluid-filled cavity opens up in the morula, the early embryonic stage of a ball of 16 cells.
The blastocyst has a diameter of about 0.1–0.2 mm and comprises 200–300 cells (32 mitotic divisions) following rapid cleavage (cell division). About seven days after fertilization,[6] the blastocyst undergoes implantation, embedding into the endometrium of the uterine wall where it will undergo further developmental processes, including gastrulation. Embedding of the blastocyst into the endometrium requires that it hatches from the zona pellucida, the egg coat that prevents adherence to the fallopian tube as the pre-embryo makes its way to the uterus.
The use of blastocysts in in vitro fertilization (IVF) involves culturing a fertilized egg for five days before transferring it into the uterus. It can be a more viable method of fertility treatment than traditional IVF. The inner cell mass of blastocysts is the source of embryonic stem cells, which are broadly applicable in stem cell therapies including cell repair, replacement and regeneration. Assisted zona hatching may also be used in IVF, and other fertility treatments.
^"27.2C: Blastocyst Formation". Medicine LibreTexts. 24 July 2018. Retrieved 11 October 2022.
^ abStandring, Susan (2016). Gray's anatomy : the anatomical basis of clinical practice (Forty-first ed.). [Philadelphia]: Elsevier Limited. p. 167. ISBN 9780702052309.
^Gilbert, Scott F. (2000). "Early Mammalian Development". Developmental Biology. 6th edition. Retrieved 13 May 2022.
The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the embryoblast...
Embryo transfer can be done at day two or day three, or later in the blastocyst stage, which was first performed in 1984. Factors that can affect the...
produce the blastocyst. Once the blastocyst is formed, it undergoes implantation into the endometrium. During implantation the blastocyst, which contains...
derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization...
A trilaminar embryonic disc, trilaminary blastoderm, or trilaminar germ disk is an early stage in the development of triploblastic organisms, which include...
contractions of the blastocyst, an increase of the pressure inside the blastocyst itself occurs, the hole expands and finally the blastocyst can emerge from...
corresponding to pre-implantation, that is, from fertilisation to the blastocyst stage. Embryo cryopreservation is useful for leftover embryos after a...
step 4 are inserted into a mouse blastocyst. For this example, we use blastocysts from a grey mouse. The blastocysts now contain two types of stem cells:...
development. At this stage in mammals the blastula develops into the blastocyst containing an inner cell mass, and outer trophectoderm. It develops following...
the early development of an embryo. It is the mass of cells inside the blastocyst that will eventually give rise to the definitive structures of the fetus...
takes the form of the blastocyst by the fifth day of development, just as it approaches the site of implantation. When the blastocyst hatches from the zona...
the blastula. In mammalian development the blastula develops into the blastocyst with a differentiated inner cell mass and an outer trophectoderm. The...
for evaluation. Embryos are generally obtained through blastomere or blastocyst biopsy. The latter technique has proved to be less deleterious for the...
distinct cell layers arising from the inner cell mass in the mammalian blastocyst, or from the blastula in reptiles and birds, the other layer is the hypoblast...
fertilization; blastomeres are an essential part of blastula formation, and blastocyst formation in mammals. In humans, blastomere formation begins immediately...
performed are cleavage stage (day 2 to 4 after co-incubation) or the blastocyst stage (day 5 or 6 after co-incubation). Embryos which reach the day 3...
fluid-filled or yolk-filled cavity that forms in the developing blastula or blastocyst in virtually all animal species. The blastocoel appears to serve two functions:...
along the fallopian tube. It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium...
after co-incubation) or the blastocyst stage (day five or six after co-incubation). Embryo culture until the blastocyst stage confers a significant increase...
abnormal sperm morphology does not appear to influence blastocyst development or blastocyst morphology. Even with severe teratozoospermia, microscopy...
blastocyst in a developing embryo. The cytotrophoblast is considered to be the trophoblastic stem cell because the layer surrounding the blastocyst remains...
130 types of mammals where this takes place, the process occurs at the blastocyst stage of embryonic development, and is characterized by a dramatic reduction...
into two, normally at the two-cell stage. If the egg splits in the early blastocyst stage, two inner cell masses will be present, eventually leading to the...
blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining...
repeatedly to give secretions of the uterine glands, ultimately forming a blastocyst. The ovum is one of the largest cells in the human body, typically visible...
temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient...
a zygote. The blastocyst stage is developed by the egg to help create embryonic stem cells from the inner cell mass of the blastocyst. The first mammal...
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