Germinal epithelium known as Germ Layer is a group of cells, formed during animal embryogenesis. Few primitive animals’ tissues are derived from two germ layers, the endoderm and ectoderm; while most animals are derived from three germ layers, the ectoderm, mesoderm and endoderm. Germ layers are known as the primary layers of cells in an embryo of an animal. As the embryo develops, the cells differentiate to form the various body tissues. In 1817, Caspar Friedrich Wolff was the first to observe the early organization in embryo in leaf-layers, while studying chick embryos, three primordial germ layers were discovered by Christian Pander. In 1871-1873, Robert Remak had further defined the concept of germ cell layer and introduced into English in terms mesoderm by Huxley in 1871 and ectoderm and endoderm by lankester in 1873.The first major event of the embryonic period happens after implantation, the three primary germ layers known as the ectoderm, mesoderm and endoderm differentiate through the blastocyst in the inner cell mass. All the tissues and organs of the body will develop from the embryonic tissues. Germ layers quickly form in human and it’s difficult to determine the events exact sequence. As the embryo develops, the cells differentiate to form the various body tissues. After a sperm fertilizes an egg for about 8 days, several divisions occurs in the embed lining of the uternus and begins to form three germ layers: ectoderm, mesoderm and endoderm, the neural crest is known as the fourth germ layer as it essential to the germ layers as it derives from the ectoderm. They are known as the embryonic tissues from which all tissues and organs are developed and that together will later make up the body. The three composed germ layers form during the gastrula stage of development. The layers are determined by their physical position in the gastrula. This stage follows the zygote and blastocyst stages; the gastrula forms when the embryo is approximately 14-16 days old in humans.Epitheral tissues develop in the embryo from all three layers. Connective tissues and muscle tissues all derive from mesoderm. Ectoderm gives rise to nervous tissue. Endoderm is the inner most of the three germ layers of the developing embryo, this germ layers produces tissues within the pancreas, lungs and thyroid this forms: the liver, intestines, the stomach, the colon, pharynx and the epithelial parts of trachea.
“Through the isolation and manipulation of cells, scientists are finding ways to identify young, regenerating ones that can be used to replace damaged of dead cells in diseased organs. This therapy is similar to the process of organ transplant, only the treatment consists of the transplantation of cells rather than organs. The cells that have shown by far the most promise of supplying diseased organs with healthy cells are called stem cells.” (Chapter Preface)
Late one night a woman is driving home on the freeway, she’s hit head on by a drunk driver and killed. The man is charged with two accounts of murder; the woman, and her four-week-old embryo inside her. By law, everyone human being is guaranteed rights of life; born or unborn they are equal. The same law should be enforced concerning human embryonic stem cell research. Dr. James A. Thomson discovered stem cells in 1998 and they’ve intrigued scientist ever since. The stem cells themselves are derived from a three to four day old cluster of cells called a blastocyst and they are so coveted because they are pluripotent, meaning they can differentiate into any type of cell in the human body. Although embryonic stem cells show amazing potential to cure various disease such as cancer, congestive heart failure, Alzheimer’s and Parkinson’s disease, muscular dystrophies, and more. The methods by which they are obtained is controversial. Research on embryonic stem cells is unethical, unnecessary, and purely homicide.
The people of ancient civilization were curious about the study of stem cells. Hindus from the thirteen and fourteen centuries BC knew that the result of the fetus would come from mixing two seeds of the parents (Kelly 16). They weren't the only people who wondered about the studies of stem cells. Greek philosopher named Aristotle was also interested in the study of stem cells so he discovered two very important theories. The two theories were Perfomation and Epigenesis (Kelly 16). According to the theory of Peromation, the fetus grows over time (Kelly 16). In contrast, Epigenesis means tat the fetus begins as a generic mass and then different parts are added to the fetus (Kelly 16).
On April 28, 2011 - the United States Appeals Court overturned the rule of a federal judge because of several issues that emerged with stem cell research being funded by the government. Although, the science of human embryonic stem cell is in its initial stages - there is much hope for scientific advancement due to the ability for human embryonic stem cells to grow into virtually various kinds of cells Favorably, advocates for stem cell research and pharmaceutical companies strongly believe that stem cells may pave a way to discover new methods of treatment for devastating ailments; such as, Leukemia, Alzheimer’s disease, Heart disease, Parkinson’s disease and diabetes- a prospect that is inspiring to both scientists and those who are seeking cures for themselves and family members. In contrast, numerous pro-life advocates are against federal funding for stem cell research because of the method in which these stem cells are extracted. In addition, several other groups argue that the federal government has abandoned more substantial as well as promising and less controversial adult and cord stem cell research. Instead, the government has dedicated a majority of their funding in favor of the more popular and controversial stem research. Ultimately, as long as humans exist - the need for a more extensive and technological progress will be abundant and crucial to humanity's survival. However, does the needs of the human species outweigh the potential lives embryos represent? With so much on the line, let us explore exactly what human embryonic stem cell (HESC) research is and what may be potentially weighing in the balance for the human race if we proceed down this road.
Sadler, T. W., and Jan Langman. Langman's Medical Embryology. Philadelphia: Lippincott Williams & Wilkins, 2006. Print.
Tissues are composed of groups of cells that have similar shapes and functions. There are four main types of tissue found in the human body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Each tissue has unique characteristics that differentiate them from one another. Epithelial tissue covers the surface of the body, connective tissue adds support and structure to the body, muscular tissue contracts to allow movement, and nervous tissue controls the organs (Hoehn & Marieb, 2007, p. 118).
The merger of two germinal cells, one being a sperm cell and the other being an egg cell, is complete within twelve hours, at which time the egg is fertilized and becomes a zygote containing forty six chromosomes required to create a new human life. It is during this remarkable process when conception occurs. Conception confirms life and makes that undeveloped human one of a kind (Rorvik & Shettles, 1983, p. 16). Many researchers, as well as scientists, identify the first moments of life as the instant when a sperm cell unites with an ovum, o...
The first period, the germinal period, is classified as the first two weeks after conception, that is identified by how fast cells divide and differentiate. During this phase a zygote duplicates. After that differentiation begins, this is where early cells take on their own characteristics and move to their predetermined locations. Once that is complete a cell mass will then become either a placenta or a nucleus, together they will become the embryo. The second period is called the embryonic period. This. Is this stage of development that occurs during the third to the eighth week after conception. During this phase, the basic structural forms of the baby's body appear. At the beginning of this period a line (the primitive streak) appears turning into the neural tube, and eventually turning into the central nervous system. in the fourth week eyes, ears, nose, mouth, and minuscule blood vessels (becoming the heart) begin to appear. Between the fifth week and the end of the embryonic period arms, legs, hands, feet, fingers, and toes appear. The final stage, the
Robert G. Edwards’ beginning stages of his years of research. Dr. Edwards’ began his research in the late 1950s, and his first obstacle was access to oocytes that were at the correct stage for in vitro fertilization. It was not until 1965 that he discovered human oocytes, “required 24 hours of incubation in vitro, before they would initiate their maturation process” (Nobelprize.org 4). Next, he had to find conditions that would encourage the fertilization of oocytes. He used the buffer conditions identified by Barr D. Bavister to activate human spermatozoa and fertilize in vitro oocytes in 1969, however the fertilized oocytes were not progressing beyond the second stage, which lead him to try to use oocytes that completed their maturation process inside the body. Laparoscopy was a new method at the time, and it allowed surgeons to remove oocytes at the appropriate stage of development. Laparoscopy is a procedure where a lighted tube is inserted through the abdomen, requiring only a small incision (WebMD 1). In 1971, this discovery, with the help of his colleague, Patrick Steptoe, allowed for advancements to the development of 8-cell stage embryos, and later 16-cell stage and blastocysts (Nobelprize.org 6,7).
Fertilization occurs when the sperm from the male and the ovum from the female combine to create a zygote. The zygote will then go through a gestational period which consists of three different stages. The first stage is the germinal stage and it starts from conception and ends at two weeks, during this stage the zygote divides and becomes much more complex and then implants into the uterine wall where it will then go on to the second stage. The second stage is the embryonic stage, this stage starts at two weeks and ends at eight weeks. During the embryonic stage the zygote has become an embryo and the organs and major body systems form and develop very rapidly. This is one of the most critical periods for physical development, the embryo is very sensitive to many different types of influences. The third and final stage of the gestational period is the fetal stage, this stage starts at eight weeks and ends at birth. During this stage the fetus grows approximately twenty times its previous length and the organs and body systems continue to develop becoming more complex and becomes ready for survival outside of the womb. Children grow the fastest during the first three years of their life, and they will never grow this rapidly again. As the child grows the child will go through various stages of physical development such as puberty and sexual maturity. After the first few
The first two weeks after conception, the germinal stage of prenatal development takes place. During this stage, a group of cells, called blastocysts, forms. The fetus relies on the mother for nutrition, which is why it is important that a mother maintains a healthy diet and nutrition. Mothers who fail to intake the necessary proteins, vitamins, and minerals during pregnancy are subjected to the malformation of their child.
The skin is made up of three layers; epidermis, dermis, and subcutaneous layer. The epidermis layer contains stem cells. Stem cells regenerate new skin if the
The female reproductive systems is made of 9 parts. The sex cell for the female reproductive system is called the egg or ovum. The egg spends it’s dormant life in the ovaries until it is released. The egg has 23 chromosomes within it. The ovaries have two goals: to create and house eggs and the release the female sex hormones, estrogen and progesterone. The fallopian tubes are what the egg travels through to reach the uterus. Fallopian tubes contain tiny hair-like structures called cilia; the cilia allows for mobility of the egg. The fallopian tube is roughly the size of 2 hairs, and is the site of where ectopic pregnancies happen. The process of the egg getting released from the ovaries through the fallopian tubes is called ovulation. Ovulation happens on the 14th day of the menstruation cycle The uterus is where the egg goes to after it travels through the fallopian tubes. The developing baby is held and nourished in the uterus. When the uterus is empty, it’s roughly the size of a fist but expands one an embryo starts to develop. The endometrium is the lining of the uterine wall. It’s used to protect the fetus. When the egg isn’t fertilized, menstruation ha...
This process is called conception, the female is now officially two weeks pregnant and the fertilized egg is called a zygote. Let’s move on to pregnancy. Pregnancy is a state in which a woman carries a fertilized egg inside her body, it usually lasts up to 40 weeks, and it is divided into three trimesters, each lasting three months. The first month. The embryo is about a third of an inch long. The head, trunk, and the beginnings of the arms and legs have started to develop. By this month, the embryo starts to receive nutrients and releases waste through the umbilical cord and placenta. The heart also starts to beat. The second month. The heart is now pumping and the nervous system, including the brain and the spinal cord begins to develop. The fetus is 1 in 2.5cm now and has developed cartilage skeleton. The arms, legs, facial features and other major organs begin to appear. The third month. The fetus has grown up to 4 in 10cm and weighs a little more than an ounce. The major blood vessels are almost completed and the face starts to show up more. The kidneys and the 4 chambers of the heart are now complete. The fourth month. The fetus is now 4 oz of 112g and can kick and swallow. The
Sally: Embryonic cells are "undifferentiated." Undifferentiated cells have not gone through changes that make some cells into skin cells or muscle cells or brain cells, for example. Undifferentiated cells can become any cell in the body because it can activate any gene on any chromosome, but as cells develop, the DNA of certain cells fold in particular ways making large portions of the DNA inaccessible. This makes sure that the wrong genes do not get turned on at the wrong time or in the wrong place.