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Prenatal Development 4Prenatal Development 4 releasing hormone (GnRH), hypothalamus, follicle-stimulating hormone (FSH) and lutenizing hormone (LH), and the pituitary gland, and estrogen and progesterone kept in the ovaries. The woman ovulates and produces one ovum (egg cell) that travels down one of her fallopian tubes. It is about 1/100" in diameter, and is barely visible to the eye.(Browder, 1991, P.146-147) When love is in the air, man and woman get together and perform the most remarkable duty there is in order to create a new life, they have sex. Their body temperatures raise, their skin comes hot and sweaty, the male genitals become erect by the flow of blood and the female’s vagina comes moist. The man then penetrates the female with his penis and eventually will ejaculate over one million sperm cells into the female which may or may not fertilized her egg. Let us say that one very lucky sperm cells did penetrate the outside ovum and fertilize it. The surface of the ovum changes its electrical characteristics and prevents additional sperm from entering the ovum. A genetically unique entity is formed shortly thereafter, called a zygote. Half of its 46 chromosomes come from the egg and the other half from the sperm. It has a unique DNA structure. This is the point that is most defined as the start of pregnancy. (Gilbert, 1997, p.84) After conception, the fertilized egg divides repeatedly into a mass of cells. The germinal period is the period of prenatal development that takes place in the first 2 weeks after conception. By 1 week after conception, the fertilized egg is composed of 100 to 150 cells. These cells have differentiated into 2 layers, an inner and outer layer. Prenatal Development 5 The blastocyst is the inner layer of these cells that develop during this period and later develop into the embryo. The outer layer is the trophoblast, which also develops during this period and later provides nutrition and support for the embryo.
Approximate Word count = 1233
Approximate Pages = 4.9
(250 words per page double spaced)
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