1.0 How does an egg becomes an adult? Human pregnancy begins with the fusion of an egg and a sperm within the female reproductive tract, but extensive stages precedes this event. First, both male and female sex cells must pass through a long series of changes under a process called gametogenesis. As the human embryologist Larsen (1997) states that gametogenesis is the process that converts primordial germ cells into mature sex gametes in the male (spermatozoa, or sperms), and in the female (definitive oocytes). The timing of gametogenesis is different in males and females. The later stages of spermatogenesis in males occur at puberty, and continue throughout adult life. The process involves the production of spermatogonia from the primitive germ cells, which in turn become primary spermatocytes, and finally mature spermatozoa. These mature sperms consist only half of the number of their original chromosomes and therefore they are ready to take part in fertilization. On the other hand, oogenesis begins in the female during fetal life. The process includes …show more content…
In comparative with most other species, mammalian cleavage is a leisurely process measured in days rather than hour. Development proceeds at the rate of roughly one cleavage division per day for the first two days. After the 2-cell stage, mammalian cleavage is asynchronous, with 1 of the 2 cells (blastomeres) dividing to form a 3-cell embryo. The embryo is then called morula when it has an approximately 16 cells. Starting after the eight-cell stage, the embryos of placenta mammals enter into a phase called compaction, during which the individual outer blastomeres tightly adhere through gap and tight junctions and lose their individual identity when viewed from the surface. The spherical mass of cells, a fluid-filled space is known as the blastocoels. At this stage, the embryo as a whole is known as
In the follicular phase, the process of the cells, glands and organs of the luteinizing hormone (LH), the follicle stimulating hormone (FSH) and oestrogen enables the maturation of the cavities, glands and sacs in the ovaries positioned through the womb to produce egg fertilization (Freudenrich 2014). In the middle of the cycle, the egg that’s fertilized sends a cue or indication through the Luteinizing hormone and the Follicle stimulating hormone signaling the eggs produced in the female reproductive system to release the fertilized eggs. In which this is where the egg travels through the fallopian tube and where it has a chance of merging with sperm, in which this is the act of fertilization. The luteal phase becomes active before and after the menstrual cycle.
In summary, I have discussed how the sperm and egg reproduce to create new individuals. I have also described the challenges with the sperm trying to reach the egg to reproduce and how the egg only chooses the most optimal sperm for reproduction. Also, discussed how the protein affects reproduction and that they change over time since they are involved in reproduction. There is future research to gain more information on why there is sometimes reproductive failure. This new research will help a great deal in understanding why an egg and sperm cannot reproduce.
Conception is the action of conceiving a child or of a child being conceived. Every human being begins life as a single cell, formed when father's sperm fertilizes mother's egg. Fertilization normally takes place in the mother's Fallopian tube, which connects the uterus (womb) with the ovary. The uterus is the size and shape of a large pear: it is made of muscle and it stretches to allow the baby's growth throughout the months of pregnancy.
This means that all the sperm in males and eggs in females are produced from meiosis. Sperm and egg cells are haploid cells-they contain only one of each type of chromosome. Meiosis actually starts with a diploid cell that undergoes two divisions; the end products are four gametes, all genetically different. Meiosis is known as a reduction division because the daughter cells always contain half the amount of chromosomes as the diploid beginner cell. Chromosomes come in pairs and these pairs are called homologous pairs. Homologous chromosomes mean that both of the chromosomes in the pair have the same gene sequence. Human somatic cells(diploid) contain 46 chromosomes consisting of 23 homologous pairs; therefore, human gametes, which are haploid, have 23 total chromosomes-one from each homologous pair. Just like in mitosis, meiosis undergoes all of the same phases. However, because meiosis involves two divisions, the cell goes through all the phases twice. When referring to the first time the cell undergoes a phase, we say 1, and when referring to the second time, we say 2. For example, when a cell starts prophase the first time in meiosis, we say it is going through prophase 1(P1). Also, there are some differences in the process itself. During P1, homologous chromosomes exchange a section of themselves in what is known as crossing over. This provides a source of genetic variation since part of each chromosome switched places with each other, thus making both chromosomes distinct from the original. Another important difference to know is that in anaphase 1, the doubled chromosomes are not separated into sister chromatids. This doesn’t happen until A2 to ensure that each of the four gametes receives one of each kind of chromosome. There are many key points to understand about meiosis. The first being that cells in meiosis do not go through interphase twice. Interphase is a “one-time” thing; DNA
You begin life as a single cell, formed when the sperm fertilises the egg. Out of all the sperm it only takes one sperm and one egg to fertilise at conception. This is called fertilization; which takes place in the Fallopian tube, the fertilized egg then divides
Darwinism, the theory of evolution, is a controversial theory that is still being contemplated today. Before the 19th century scientist were puzzled by the idea of where humans, plants, and animals originated. In the late 1700s the question was first tried by a group of scientist, but they were not successful. It was not until a young Charles Darwin found interest in the subject that the discovery was finally able to become a theory. His observations led to his theory of evolution by natural selection. Although, it was a new discovery that shocked so many, Darwin and his accomplices did not realize how significant their newfound theory was. ~~~~
The initial product of the union of ovum and sperm; a fertilized ovum, is called the zygote. It begins as a single cell and rapidly divides to become a blastocyst or the development stage of the zygote when it is about 5 days old and ready for implantation; the embedding of the blastocyst in the inner uterine wall. Cell
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
A male makes one thousand new sperm per second, that is two trillion over a lifetime and they all are one of a kind, very unique. A woman has all her eggs from birth. The process starts out as meiosis, this is where 30,000 genes are then there are forty six chromosomes. Twenty three comes from your mother and twenty three come from your father, they only come together in meiosis in pairs, but they are not the same. Chromosomes make an exact copy of themselves then they condense making an X shape, chromosomes get a partner then embrace. The chromosomes cling close together in big chunks, the cell then divides pulling the pair apart with twenty three chromosomes. The cell alone is incomplete, but holds many promises. Every cell holds di...
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
Synthetic biology, also known as synbio, is a new form of research that began in the year 2000. The Action Group on Erosion, Technology and Concentration (ETC Group) says that synthetic biology is bringing together “engineering and the life sciences in order to design and construct new biological parts, devices and systems that do not currently exist in the natural world’ (Synthetic Biology). Synthetic biology is aiming to create safer medicines, clean energy, and help the environment through synthetically engineered medicines, biofuels, and food. Because synthetic biology has only existed for fourteen years, there is controversy involving its engineering ethics. In this literature review, I am going to summarize and correlate the International Association for Synthetic Biology (IASB) Code of Conduct for Gene Synthesis, the impact of synthetic biology on people and the environment, and the philosophical debates.
"Embryonic stem cells are derived from a four- or five-day-old human embryo that is in the blastocyst phase of development."(source). Before the embryonic stem is produced, the fertilized egg, a zygote, starts to multiply it's cells. Once the group of cells is set in the uterus, it becomes a blastocyst. The blastocyst consists of an inner and outer mass. The outer mass, 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