Search results
Results from the WOW.Com Content Network
Levonorgestrel-releasing implant prevents pregnancy through multiple methods: by preventing ovulation, which means that no eggs are released for fertilization; by thickening the mucus of the cervix, which prevents sperm from entering; and by thinning the lining of the uterus, which makes implantation of an embryo less likely. [9]
Implantation bleeding occurs between 7 and 14 days after fertilization, [57] and is a small amount of light vaginal bleeding or spotting that can occur in early pregnancy due to the blastocyst penetrating the lining of the uterus during implantation.
Embryonic stem cells (ESCs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. [1] [2] Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells.
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus.
The germinal stage refers to the time from fertilization, through the development of the early embryo, up until implantation. The germinal stage is over at about 10 days of gestation. [2] The zygote contains a full complement of genetic material with all the biological characteristics of a single human being, and develops into the embryo.
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 100-200 cells following 7-8 rounds of cleavage (cell division without cell growth).
At the 16–cell stage the compacted embryo is called a morula. [14] [15] Once the embryo has divided into 16 cells, it begins to resemble a mulberry, hence the name morula (Latin, morus: mulberry). [16] Concomitantly, they develop an inside-out polarity that provides distinct characteristics and functions to their cell-cell and cell-medium ...
After four divisions, the conceptus consists of 16 blastomeres, and it is known as the morula. [8] Through the processes of compaction, cell division, and blastulation, the conceptus takes the form of the blastocyst by the fifth day of development, just as it approaches the site of implantation. [ 9 ]