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In addition to sideward bendings of the head, complex and generalized movements occur at the beginning of the fetal stage, with movements and startles that involve the whole body. [11] Movement of hands, hips and knees have been observed at nine weeks, [12] stretches and yawns at ten weeks, [13] and isolated limb movements beginning shortly ...
Quickening indicates the start of fetal movements, usually felt 14–26 weeks after conception, or between the fourth and sixth month. [ 5 ] [ 6 ] A woman pregnant for the first time (i.e., a primigravida woman) typically feels fetal movements at about 20–21 weeks, whereas a woman who has given birth at least once will typically feel ...
The 46 chromosomes undergo changes prior to the mitotic division which leads to the formation of the embryo having two cells. Successful fertilization is enabled by three processes, which also act as controls to ensure species-specificity. The first is that of chemotaxis which directs the movement of the sperm towards the ovum. [2]
A great many sperm cells are released with the possibility of just one managing to adhere to and enter the thick protective layer surrounding the egg cell (ovum). The first sperm cell to successfully penetrate the egg cell donates its genetic material to combine with the DNA of the egg cell resulting in a new one-celled zygote.
The gestational sac is spherical in shape, and is usually located in the upper part (fundus) of the uterus.By approximately nine weeks of gestational age, due to folding of the trilaminar germ disc, the amniotic sac expands and occupy the majority of the volume of the gestational sac, eventually reducing the extraembryonic coelom (the gestational sac or the chorionic cavity) to a thin layer ...
Cell division begins approximately 24 to 36 hours after the female and male cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as a blastocyst. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known as implantation.
At least three discrete body/limb movement in 30 minutes (episodes of active continuous movement considered a single movement. Less than three or two [3] movements US: Fetal muscle tone At least one [3] episode of active extension with return to flexion of fetal limb(s) or trunk, opening and closing of hand considered to be normal tone.
The fetal membranes surround the developing embryo and form the fetal-maternal interface. [3] The fetal membranes are derived from the trophoblast layer (outer layer of cells) of the implanting blastocyst. [3] The trophoblast layer differentiates into amnion and the chorion, which then comprise the fetal membranes. [4]