This PDF file was converted by Atop CHM to PDF Converter free version! It is customary to divide human development into prenatal (before birth) and Moore KL, Persaud TVN, Shiota K: Color Atlas of Clinical Embryology, 2nd ed. Request PDF on ResearchGate | On Jan 1, , Keith L. Moore and others published The Developing Human. Clinically Oriented Embryology. Persaud, Mark G. Torchia. [Matching item] The developing human clinically oriented embryology Keith L. Moore ; [illustrated by Glen Reid] [electronic resource] - 2d ed. [Matching item] The Developing Human [electronic resource]: Clinically Oriented Embryology.
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Description of Human Development: Alaqah and Mudghah Stages. Keith L. Moore, Abdul-Majeed A. Zindani and Mustafa A. Ahmed [keith haiwingbasoftdif.ml] the developing human - clinically oriented embryology (8th ed.) - dokument [*.pdf] 1 / 1 Introduction to the Developing. In this part of the article, you will be able to access haiwingbasoftdif.ml file of The Developing Human: Clinically Oriented Embryology 8th Edition PDF by using our direct.
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Most terms have Latin L. Oocyte L. The female germ or sexcells are produced in the ovaries. When mature, the oocytes are called secondaryoocytes or mature oocytes.
Sperm Gr. The sperm, or spermatozoon, refers to the male germ cell produced in the testes testicles. Numerous sperms spermatozoa are expelled from the male urethra during ejaculation. This cell results from the union of an oocyte and a sperm during fertilization. Azygote or embryo is the beginning of a new human being. Gestational Age. It is difficult to determine exactlywhen fertilization conception occurs because the process cannot be observed in vivo within the living body.
Physicians calculate the age of the embryo or fetus from the presumed first dayof the last normal menstrual period. This is the gestational age, which is approximately2 weeks longer than the fertilization age because the oocyte is not fertilized until approximately2 weeks after the preceding menstruation see Fig.
This is the series of mitotic cell divisions of the zygote that result in the formation of earlyembryonic cells, blastomeres. The size of the cleaving zygote remains unchanged because at each succeeding cleavage division, the blastomeres become smaller. Morula L. This solid mass of 12 to approximately32 blastomeres is formed bycleavage of a zygote.
The blastomeres change their shape and tightlyalign themselves against each other to form a compact ball of cells. This phenomenon, compaction, is probablymediated bycell surface adhesion glycoproteins.
The morula stage occurs 3 to 4 days after fertilization, just as the earlyembryo enters the uterus. Blastocyst Gr. After 2 to 3 days, the morula enters the uterus from the uterine tube fallopian tube. Soon a fluid- filled cavity, the blastocystic cavity, develops inside it. This change converts the morula into a blastocyst.
Its centrallylocated cells, the inner cell mass or embryoblast, is the embryonic part of the embryo. The process during which the blastocyst attaches to the endometrium, the mucous membrane or lining of uterus, and subsequently embeds in it. The preimplantation period of embryonic development is the time between fertilization and the beginning of implantation, a period of approximately6 days. Gastrula Gr. During gastrulation transformation of a blastocyst into a gastrula , a three-layered or trilaminar embryonic disc forms third week.
The three germ layers of the gastrula ectoderm, mesoderm, and endoderm subsequentlydifferentiate into the tissues and organs of the embryo. Neurula Gr. The earlyembryo during the third and fourth weeks when the neural tube is developing from the neural plate see Fig. It is the first appearance of the nervous system and the next stage after the gastrula. Embryo Gr. The developing human during its earlystages of development. The embryonic period extends to the end of the eighth week 56 days , bywhich time the beginnings of all major structures are present.
The size of embryos is given as crown-rump length, which is measured from the vertexof the cranium crown of head to the rump buttocks. Stages of Prenatal Development. Earlyembryonic development is described in stages because of the variable period it takes for embryos to develop certain morphologic characteristics see Fig. Stage 1 begins at fertilization and embryonic development ends at stage 23, which occurs on day The fetal period begins on day57 and ends when the fetus is completelyoutside the mother.
Failing to understand the consequences of our inventions while we are in the rapture of discovery and innovation seems to be a common fault of scientists and technologists; we have long been driven by the overarching desire to know that is the nature of science's quest, not stopping to notice that the progress to newer and more powerful technologies can take on a life of its own.
I have long realized that the big advances in information technology come not from the work of computer scientists, computer architects, or electrical engineers, but from that of physical scientists.
The physicists Stephen Wolfram and Brosl Hasslacher introduced me, in the early s, to chaos theory and nonlinear systems. In the s, I learned about complex systems from conversations with Danny Hillis, the biologist Stuart Kauffman, the Nobel-laureate physicist Murray Gell-Mann, and others.
Most recently, Hasslacher and the electrical engineer and device physicist Mark Reed have been giving me insight into the incredible possibilities of molecular electronics.
In my own work, as codesigner of three microprocessor architectures—SPARC, picoJava, and MAJC—and as the designer of several implementations thereof, I've been afforded a deep and firsthand acquaintance with Moore's law.
For decades, Moore's law has correctly predicted the exponential rate of improvement of semiconductor technology. Until last year I believed that the rate of advances predicted by Moore's law might continue only until roughly , when some physical limits would begin to be reached.
It was not obvious to me that a new technology would arrive in time to keep performance advancing smoothly. But because of the recent rapid and radical progress in molecular electronics—where individual atoms and molecules replace lithographically drawn transistors—and related nanoscale technologies, we should be able to meet or exceed the Moore's law rate of progress for another 30 years.
By , we are likely to be able to build machines, in quantity, a million times as powerful as the personal computers of today—sufficient to implement the dreams of Kurzweil and Moravec. As this enormous computing power is combined with the manipulative advances of the physical sciences and the new, deep understandings in genetics, enormous transformative power is being unleashed. These combinations open up the opportunity to completely redesign the world, for better or worse: The replicating and evolving processes that have been confined to the natural world are about to become realms of human endeavor.
In designing software and microprocessors, I have never had the feeling that I was designing an intelligent machine. The software and hardware is so fragile and the capabilities of the machine to "think" so clearly absent that, even as a possibility, this has always seemed very far in the future.
But now, with the prospect of human-level computing power in about 30 years, a new idea suggests itself: that I may be working to create tools which will enable the construction of the technology that may replace our species. How do I feel about this? Very uncomfortable. Having struggled my entire career to build reliable software systems, it seems to me more than likely that this future will not work out as well as some people may imagine.
My personal experience suggests we tend to overestimate our design abilities. Given the incredible power of these new technologies, shouldn't we be asking how we can best coexist with them?
And if our own extinction is a likely, or even possible, outcome of our technological development, shouldn't we proceed with great caution? The dream of robotics is, first, that intelligent machines can do our work for us, allowing us lives of leisure, restoring us to Eden. Yet in his history of such ideas, Darwin Among the Machines, George Dyson warns: "In the game of life and evolution there are three players at the table: human beings, nature, and machines.
I am firmly on the side of nature. But nature, I suspect, is on the side of the machines. How soon could such an intelligent robot be built?
The coming advances in computing power seem to make it possible by And once an intelligent robot exists, it is only a small step to a robot species—to an intelligent robot that can make evolved copies of itself.
A second dream of robotics is that we will gradually replace ourselves with our robotic technology, achieving near immortality by downloading our consciousnesses; it is this process that Danny Hillis thinks we will gradually get used to and that Ray Kurzweil elegantly details in The Age of Spiritual Machines. We are beginning to see intimations of this in the implantation of computer devices into the human body, as illustrated on the cover of Wired 8.
But if we are downloaded into our technology, what are the chances that we will thereafter be ourselves or even human? It seems to me far more likely that a robotic existence would not be like a human one in any sense that we understand, that the robots would in no sense be our children, that on this path our humanity may well be lost.
Genetic engineering promises to revolutionize agriculture by increasing crop yields while reducing the use of pesticides; to create tens of thousands of novel species of bacteria, plants, viruses, and animals; to replace reproduction, or supplement it, with cloning; to create cures for many diseases, increasing our life span and our quality of life; and much, much more. We now know with certainty that these profound changes in the biological sciences are imminent and will challenge all our notions of what life is.
Technologies such as human cloning have in particular raised our awareness of the profound ethical and moral issues we face. If, for example, we were to reengineer ourselves into several separate and unequal species using the power of genetic engineering, then we would threaten the notion of equality that is the very cornerstone of our democracy.
Given the incredible power of genetic engineering, it's no surprise that there are significant safety issues in its use. My friend Amory Lovins recently cowrote, along with Hunter Lovins, an editorial that provides an ecological view of some of these dangers.
Among their concerns: that "the new botany aligns the development of plants with their economic, not evolutionary, success. Amory's long career has been focused on energy and resource efficiency by taking a whole-system view of human-made systems; such a whole-system view often finds simple, smart solutions to otherwise seemingly difficult problems, and is usefully applied here as well.
Unless the Luddites win. Certainly not. I believe we all would agree that golden rice, with its built-in vitamin A, is probably a good thing, if developed with proper care and respect for the likely dangers in moving genes across species boundaries.
Awareness of the dangers inherent in genetic engineering is beginning to grow, as reflected in the Lovins' editorial. The general public is aware of, and uneasy about, genetically modified foods, and seems to be rejecting the notion that such foods should be permitted to be unlabeled.
But genetic engineering technology is already very far along. As the Lovins note, the USDA has already approved about 50 genetically engineered crops for unlimited release; more than half of the world's soybeans and a third of its corn now contain genes spliced in from other forms of life.
While there are many important issues here, my own major concern with genetic engineering is narrower: that it gives the power—whether militarily, accidentally, or in a deliberate terrorist act—to create a White Plague. The many wonders of nanotechnology were first imagined by the Nobel-laureate physicist Richard Feynman in a speech he gave in , subsequently published under the title "There's Plenty of Room at the Bottom.
A subsequent book, Unbounding the Future: The Nanotechnology Revolution, which Drexler cowrote, imagines some of the changes that might take place in a world where we had molecular-level "assemblers.
I remember feeling good about nanotechnology after reading Engines of Creation. As a technologist, it gave me a sense of calm—that is, nanotechnology showed us that incredible progress was possible, and indeed perhaps inevitable.
If nanotechnology was our future, then I didn't feel pressed to solve so many problems in the present. I would get to Drexler's utopian future in due time; I might as well enjoy life more in the here and now. It didn't make sense, given his vision, to stay up all night, all the time. Drexler's vision also led to a lot of good fun. I would occasionally get to describe the wonders of nanotechnology to others who had not heard of it.
After teasing them with all the things Drexler described I would give a homework assignment of my own: "Use nanotechnology to create a vampire; for extra credit create an antidote. As I said at a nanotechnology conference in , "We can't simply do our science and not worry about these ethical issues.
Shortly thereafter I moved to Colorado, to a skunk works I had set up, and the focus of my work shifted to software for the Internet, specifically on ideas that became Java and Jini. Then, last summer, Brosl Hasslacher told me that nanoscale molecular electronics was now practical. This was new news, at least to me, and I think to many people—and it radically changed my opinion about nanotechnology.
It sent me back to Engines of Creation. Rereading Drexler's work after more than 10 years, I was dismayed to realize how little I had remembered of its lengthy section called "Dangers and Hopes," including a discussion of how nanotechnologies can become "engines of destruction.
Having anticipated and described many technical and political problems with nanotechnology, Drexler started the Foresight Institute in the late s "to help prepare society for anticipated advanced technologies"—most important, nanotechnology. The enabling breakthrough to assemblers seems quite likely within the next 20 years.
Molecular electronics—the new subfield of nanotechnology where individual molecules are circuit elements—should mature quickly and become enormously lucrative within this decade, causing a large incremental investment in all nanotechnologies. Unfortunately, as with nuclear technology, it is far easier to create destructive uses for nanotechnology than constructive ones.
Nanotechnology has clear military and terrorist uses, and you need not be suicidal to release a massively destructive nanotechnological device—such devices can be built to be selectively destructive, affecting, for example, only a certain geographical area or a group of people who are genetically distinct.
An immediate consequence of the Faustian bargain in obtaining the great power of nanotechnology is that we run a grave risk—the risk that we might destroy the biosphere on which all life depends. As Drexler explained: "Plants" with "leaves" no more efficient than today's solar cells could out-compete real plants, crowding the biosphere with an inedible foliage. Tough omnivorous "bacteria" could out-compete real bacteria: They could spread like blowing pollen, replicate swiftly, and reduce the biosphere to dust in a matter of days.
Dangerous replicators could easily be too tough, small, and rapidly spreading to stop—at least if we make no preparation.
We have trouble enough controlling viruses and fruit flies. Among the cognoscenti of nanotechnology, this threat has become known as the "gray goo problem. They might be superior in an evolutionary sense, but this need not make them valuable. The gray goo threat makes one thing perfectly clear: We cannot afford certain kinds of accidents with replicating assemblers.
Gray goo would surely be a depressing ending to our human adventure on Earth, far worse than mere fire or ice, and one that could stem from a simple laboratory accident.
It is most of all the power of destructive self-replication in genetics, nanotechnology, and robotics GNR that should give us pause. Self-replication is the modus operandi of genetic engineering, which uses the machinery of the cell to replicate its designs, and the prime danger underlying gray goo in nanotechnology. Stories of run-amok robots like the Borg, replicating or mutating to escape from the ethical constraints imposed on them by their creators, are well established in our science fiction books and movies.
It is even possible that self-replication may be more fundamental than we thought, and hence harder—or even impossible—to control.
A recent article by Stuart Kauffman in Nature titled "Self-Replication: Even Peptides Do It" discusses the discovery that a amino-acid peptide can "autocatalyse its own synthesis. But these warnings haven't been widely publicized; the public discussions have been clearly inadequate.
There is no profit in publicizing the dangers. The nuclear, biological, and chemical NBC technologies used in 20th-century weapons of mass destruction were and are largely military, developed in government laboratories. In sharp contrast, the 21st-century GNR technologies have clear commercial uses and are being developed almost exclusively by corporate enterprises.
In this age of triumphant commercialism, technology—with science as its handmaiden—is delivering a series of almost magical inventions that are the most phenomenally lucrative ever seen. We are aggressively pursuing the promises of these new technologies within the now-unchallenged system of global capitalism and its manifold financial incentives and competitive pressures.
This is the first moment in the history of our planet when any species, by its own voluntary actions, has become a danger to itself—as well as to vast numbers of others. It might be a familiar progression, transpiring on many worlds—a planet, newly formed, placidly revolves around its star; life slowly forms; a kaleidoscopic procession of creatures evolves; intelligence emerges which, at least up to a point, confers enormous survival value; and then technology is invented. It dawns on them that there are such things as laws of Nature, that these laws can be revealed by experiment, and that knowledge of these laws can be made both to save and to take lives, both on unprecedented scales.
Science, they recognize, grants immense powers. In a flash, they create world-altering contrivances. Some planetary civilizations see their way through, place limits on what may and what must not be done, and safely pass through the time of perils.
Others, not so lucky or so prudent, perish. That is Carl Sagan, writing in , in Pale Blue Dot, a book describing his vision of the human future in space. I am only now realizing how deep his insight was, and how sorely I miss, and will miss, his voice. For all its eloquence, Sagan's contribution was not least that of simple common sense—an attribute that, along with humility, many of the leading advocates of the 21st-century technologies seem to lack.
I remember from my childhood that my grandmother was strongly against the overuse of antibiotics. She had worked since before the first World War as a nurse and had a commonsense attitude that taking antibiotics, unless they were absolutely necessary, was bad for you.
It is not that she was an enemy of progress. She saw much progress in an almost year nursing career; my grandfather, a diabetic, benefited greatly from the improved treatments that became available in his lifetime. But she, like many levelheaded people, would probably think it greatly arrogant for us, now, to be designing a robotic "replacement species," when we obviously have so much trouble making relatively simple things work, and so much trouble managing—or even understanding—ourselves.
I realize now that she had an awareness of the nature of the order of life, and of the necessity of living with and respecting that order. With this respect comes a necessary humility that we, with our earlyst-century chutzpah, lack at our peril.
The commonsense view, grounded in this respect, is often right, in advance of the scientific evidence. The clear fragility and inefficiencies of the human-made systems we have built should give us all pause; the fragility of the systems I have worked on certainly humbles me.
We should have learned a lesson from the making of the first atomic bomb and the resulting arms race. We didn't do well then, and the parallels to our current situation are troubling.
The effort to build the first atomic bomb was led by the brilliant physicist J. Robert Oppenheimer. Oppenheimer was not naturally interested in politics but became painfully aware of what he perceived as the grave threat to Western civilization from the Third Reich, a threat surely grave because of the possibility that Hitler might obtain nuclear weapons.
Energized by this concern, he brought his strong intellect, passion for physics, and charismatic leadership skills to Los Alamos and led a rapid and successful effort by an incredible collection of great minds to quickly invent the bomb. What is striking is how this effort continued so naturally after the initial impetus was removed. In a meeting shortly after V-E Day with some physicists who felt that perhaps the effort should stop, Oppenheimer argued to continue. His stated reason seems a bit strange: not because of the fear of large casualties from an invasion of Japan, but because the United Nations, which was soon to be formed, should have foreknowledge of atomic weapons.
A more likely reason the project continued is the momentum that had built up—the first atomic test, Trinity, was nearly at hand. We know that in preparing this first atomic test the physicists proceeded despite a large number of possible dangers. They were initially worried, based on a calculation by Edward Teller, that an atomic explosion might set fire to the atmosphere. A revised calculation reduced the danger of destroying the world to a three-in-a-million chance.
Teller says he was later able to dismiss the prospect of atmospheric ignition entirely. Oppenheimer, though, was sufficiently concerned about the result of Trinity that he arranged for a possible evacuation of the southwest part of the state of New Mexico. And, of course, there was the clear danger of starting a nuclear arms race.
Within a month of that first, successful test, two atomic bombs destroyed Hiroshima and Nagasaki. Some scientists had suggested that the bomb simply be demonstrated, rather than dropped on Japanese cities—saying that this would greatly improve the chances for arms control after the war—but to no avail.
With the tragedy of Pearl Harbor still fresh in Americans' minds, it would have been very difficult for President Truman to order a demonstration of the weapons rather than use them as he did—the desire to quickly end the war and save the lives that would have been lost in any invasion of Japan was very strong.
Yet the overriding truth was probably very simple: As the physicist Freeman Dyson later said, "The reason that it was dropped was just that nobody had the courage or the foresight to say no. They describe a series of waves of emotion: first, a sense of fulfillment that the bomb worked, then horror at all the people that had been killed, and then a convincing feeling that on no account should another bomb be dropped. Yet of course another bomb was dropped, on Nagasaki, only three days after the bombing of Hiroshima.
In November , three months after the atomic bombings, Oppenheimer stood firmly behind the scientific attitude, saying, "It is not possible to be a scientist unless you believe that the knowledge of the world, and the power which this gives, is a thing which is of intrinsic value to humanity, and that you are using it to help in the spread of knowledge and are willing to take the consequences.
This proposal led to the Baruch Plan, which was submitted to the United Nations in June but never adopted perhaps because, as Rhodes suggests, Bernard Baruch had "insisted on burdening the plan with conventional sanctions," thereby inevitably dooming it, even though it would "almost certainly have been rejected by Stalinist Russia anyway". Other efforts to promote sensible steps toward internationalizing nuclear power to prevent an arms race ran afoul either of US politics and internal distrust, or distrust by the Soviets.
The opportunity to avoid the arms race was lost, and very quickly.