• Define gestational age compared to developmental age • Explain the trimester system of embryological development • Describe the development on a week by week basis throughout pregnancy from the time of fertilization to birth • Understand the stages of development that are sensitive to abnormalities and are at an increased risk of spontaneous abortions • Define aneuploidy and explain its significance to spontaneous abortions • Define confined placental mosaicism, explain how it occurs and why it significant • Review how twins arise and how it might matter regarding the sharing or lack of sharing of the embryonic membranes and placenta • Explain the composition and functions of the extra-embryonic tissue and membranes • Review methods …show more content…
http://wps.aw.com/bc_martini_eap_5/108/27714/7094998.cw/index.html • Fertilization: - Fertilization: the fusion of the mature sperm cell with the secondary oocyte, resulting in the genetic material from two haploid cells fusing to form a single diploid cell - Chances of fertilization: Sperm are viable for 48 hours after it is deposited into the female, but the oocyte cell is only viable for 24 hours after ovulation. This results in a 3 day window for fertilization to take place - Fertilization occurs in the fallopian tubes. - In order for fertilization to occur the sperm must penetrate the corona radiata and then the zona pellucida before it can fuse with the plasma membrane of the oocyte. It burrows into the corona radiata and binds to a sperm receptor, one of the glycoprotein’s in the zona pellucida which causes the head of the sperm to release enzymes that digest through the zona pellucida, making a path for the sperm to the plasma membrane of the secondary oocyte. Once the two plasma membranes come in contact with each other, they fuse and the sperm nucleus is released into
Over time, the sperm and egg have evolved to be different. The article mentions the challenges with the sperm being able to reach the egg. There is also a discussion about how the protein affects the reproduction and a discussion on reproductive failure. The main concepts are how the egg and sperm reproduce, the challenges the sperm faces to get to the egg, how the egg and the sperm have evolved over time, and protein affects reproduction and reproductive failure. The outer shell of the egg has a sugary compound that allows the sperm to bind to the egg, resulting in reproduction.
Twins are truly fascinating from the time of separation of the embryo to birth; and still the complexity of twinning is not yet fully understood among the scientific world. Scientists have studied the human body from the time of prenatal development to birth, and still are in awe of the formation of twins. Research in twinning is ever more increasing in this field, leadi...
During ovulation, when a woman releases an ovum, three different processes can occur. First, the ovum can remain in one piece all the way to the uterus where, if not fertilized, it will be shed out of the body along with the unused endometrium. Second, the ovum, if fertilized, can develop into a single embryo, which is the most common type of pregnancy in humans with about 99% of all births being singletons (1). Finally, the ovum can split into two separate halves resulting in genetically identical twins. The three types of twins previously mentioned are identical, which are created when the fertilized ovum separates into two complete, identical parts, conjoined, which occur as a result of a fertilized ovum not completing the equal separation resulting in two fetuses fused together in some way, and half-twins or polar body twins, which are made when an unfertilized ovum splits into two complete, identical parts and is then fertilized by two different sperm. The frequency of identical twins is 3.5 per 100 births (1) and the frequency of conjoined twins is 1 birth per 50,000 with only 100 known cases surviving their first year (5).
Conjoined twins have one major cause, which makes them conjoined. When an egg is produced and is fertilized by sperm, 3 things can happen, the egg can grow and form only one fetus, the egg can split and form identical twins (triplets) or the egg can partially split and grow into conjoined twins. Usually identical twins are formed during the first 12 days after the conception date, but when the process happens the 13th or 14th day, the egg doesn’t fully se...
Peterson-Iyer, Karen. "Confronting a Fetal Abnormality." http://www.scu.edu. Santa Clara University, Jan. 2008. Web. 13 Mar. 2014. .
The history in a family can influence many generations. Certain families have stereotypes about them based on family history. This is a real world situation; the movie The Pregnancy Project, stereotypes about teen pregnancy where shown, and how they affect people. In the Pregnancy Project, the use of Gabi’s background influenced people’s reactions because her family has a history of teen pregnancy.
Although there are many factors that affect the development of the fetus, research on the specific effects of prenatal maternal stress and the resulting negative outcomes for the development of the fetus will be reviewed. While there is knowledge of these harmful effects in scientific and medical communities, researchers are still in the midst of discovering the results of these negative effects on human development. An overall review of the literature suggests that this topic is still relatively new in research as most of the articles make note that despite the amount of current research studies, there are still many unanswered questions.
Even before women know they’re pregnant important changes are already happening in their bodies. The first week of conception the zygote this is when the egg and sperm join it now has divided into many cells. Within two weeks the embryo will attach to the woman’s uterine wall. The embryo will continue to grow climaxing with the baby’s birth.
Fraternal twins are the most common type of twins. They are the result of the union of two eggs and two sperm. Fraternal twins can be the same or different sexes (Wade 53). Segal says that, “They are two individuals, no more genetically alike than brothers and sisters that develop from separate fertilizations” (Segal 1). Amazingly, fraternal twins can be conceived at separate times and have different fathers. It seems to be a hereditable trait to conceive fraternal twins. Yet, tendency to conceive conjoined twins may be caused by genetic and environmental conditions (Hunter 1).
Prenatal development is often overlooked, but it is an important topic that everyone is influenced by. Mothers’ actions during pregnancy greatly affect the child (for good or for bad). There are many factors to a baby’s development of the brain, intelligence, and emotions. What a mother puts into her body affects the baby’s development. How stressed the mother is also contributes to development. A mother’s job during pregnancy cannot be overstated, because she is the main protector and nurturer of the child in the womb. How she handles her own emotional and physical health will determine the development of the baby inside and outside of the womb. The decisions a pregnant woman makes affects not only her health, but the health of her child.
Gestational diabetes is a form of diabetes that occurs during pregnancy. Although it usually goes away after the baby is born, it does bring health risks for both the mother and baby. When you’re pregnant, pregnancy hormones make it harder for insulin to move glucose from your blood into the cells. If your body can’t produce enough insulin to overcome the effects of insulin resistance, you’ll develop gestational diabetes. (IHC, 2013)
Sadler, T. W., and Jan Langman. Langman's Medical Embryology. Philadelphia: Lippincott Williams & Wilkins, 2006. Print.
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...
I have always been fascinated by conjoined twins and have always had questions about them like; what do the Siamese have to do with conjoined twins? Why does this form of twin happen? What, if any genes cause this? What types of Conjoined twins are there? How does the environment affect, if at all, the biological families' gene pool? In my research in efforts to prepare this paper, I found the answers to this question and many more. This term paper will cover the types of conjoined twins, the biological occurrence that causes conjoined twins, a look into some of the genetic and environmental causes of conjoined twins, the types of conjoined twins and the genetic and social impact of conjoined twins.
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