Embryology Quotes

If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race.

The embryological record is almost always abbreviated in accordance with the tendency of nature (to be explained on the principle of survival of the fittest) to attain her needs by the easiest means.

[...] I believe in Natural Selection, not because I can prove in any single case that it has changed one species into another, but because it groups and explains well (as it seems to me) a host of facts in classification, embryology, morphology, rudimentary organs, geological succession and distribution.

... Because the staging of human embryos is complex, owing to the continuous process of change during development, it is proposed that a new system of classification could be developed using the terms mentioned in the Qur'an and Sunnah. The proposed system is simple, comprehensive, and conforms with present embryological knowledge.287 (Dr. Keith L. Moore, Professor Emeritus, Department of Anatomy and Cell Biology, University of Toronto)

I check every can of Barbasol I buy for dinosaur embryos. I haven't found any yet, as evidenced by the lack of T-Rex screams in my apartment.

Science cannot tell you whether abortion is wrong, but it can point out that the (embryological) continuum that seamlessly joins a non-sentient foetus to a sentient adult is analogous to the (evolutionary) continuum that joins humans to other species. If the embryological continuum appears to be more seamless, this is only because the evolutionary continuum is divided by the accident of extinction. Fundamental principles of ethics should not depend on the accidental contingencies of extinction.* To repeat, science cannot tell you whether abortion is murder, but it can warn you that you may be being inconsistent if you think abortion is murder but killing chimpanzees is not. You cannot have it both ways.

Embryology will reveal to us the structure, in some degree obscured, of the prototypes of each great class.

It is undignified to inject yourself with hormones designed to slow or enhance ovarian production. It is undignified to have your ovaries monitored by transvaginal ultrasound; to be sedated so that your eggs can be aspirated into a needle; to have your husband emerge sheepishly from a locked room with the “sample” that will be combined with your eggs under supervision of an embryologist. The grainy photo they hand you on transfer day, of your eight-celled embryo (which does not look remotely like a baby), is undignified, and so is all the waiting and despairing that follows.

When your grandmother was five months pregnant with your mother, the precursor cell of the egg you developed from was already present in your mother’s ovaries. This means that before your mother was even born, your mother, your grandmother, and the earliest traces of you were all in the same body—three generations sharing the same biological environment.1 This isn’t a new idea: embryology textbooks have told us as much for more than a century. Your inception can be similarly traced in your paternal line. The precursor cells of the sperm you developed from were present in your father when he was a fetus in his mother’s womb.

Biology taught me that a field undergoing development should be investigated always from the viewpoint of its past development. Who today would study anatomy without embryology? In exactly the same way epistemology without historical and comparative investigations is no more than an empty play on words or an epistemology of the imagination.

But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that, when there is no apparent reason why a peculiarity should appear at any particular age, yet it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology.

good mother will make a point of having sex with several different men, especially when she is pregnant, so that her child will enjoy the qualities (and paternal care) not merely of the best hunter, but also of the best storyteller, the strongest warrior and the most considerate lover. If this sounds silly, bear in mind that before the development of modern embryological studies, people had no solid evidence that babies are always sired by a single father rather than by many.

Were I to become the scholar I once hoped to be, I would choose such moments of political embryology as my field of study, and concentrate first on Germany. I would choose Germany because in 1933 a handful of men had seized a modern state and made its people into the most hated nation in the world. In 1949 and 1950 I saw another handful of men take over in Germany- dull, dreary, plodding men- and saw them convert Germany in the next twenty years into a decent society. What frightened me then, and frightens me still, is how very few men it takes at the head of any state to give it its character of good or evil, of freedom, tyranny, torture, butchery or benevolence.

Do not expect to hear of any system or method on my part ; time seems too short and the world too vast for that! I rush from science to philosophy, and from philosophy to our old friends the poets; and then, over-wearied by too much idealism, I fancy I become practical in returning to science. Have you ever attempted to conceive all there is in the world worth knowing—that not one subject in the universe is unworthy of study? The giants of literature, the mysteries of many-dimensional space, the attempts of Boltzmann and Crookes to penetrate Nature's very laboratory, the Kantian theory of the universe, and the latest discoveries in embryology, with their wonderful tales of the development of life—what an immensity beyond our grasp!

There are even a number of present-day human cultures in which collective fatherhood is practised, as for example among the Barí Indians. According to the beliefs of such societies, a child is not born from the sperm of a single man, but from the accumulation of sperm in a woman’s womb. A good mother will make a point of having sex with several different men, especially when she is pregnant, so that her child will enjoy the qualities (and paternal care) not merely of the best hunter, but also of the best storyteller, the strongest warrior and the most considerate lover. If this sounds silly, bear in mind that before the development of modern embryological studies, people had no solid evidence that babies are always sired by a single father rather than by many.

To sum up: at various stages of embryonic development, and at various structural levels, we find different biochemical mechanisms, but analogue principles at work. At every stage and level the game is played according to fixed rules but with flexible strategies (although their flexibility is normally hidden from the eye and revealed only by the transplantation and grafting techniques of experimental embryology). The overall rules of the game are laid down in the complete set of instructions operative at any level at any time is triggered off by messages from the inter- and extra-cellular environment, which vary in character according to structural level and developmental stage: fertilizing agents, cytoplasmic feedbacks, direct-contact evocators, hormones, and other catalysts.

The extracellular genesis of cells in animals seemed to me, ever since the publication of the cell theory [of Schwann], just as unlikely as the spontaneous generation of organisms. These doubts produced my observations on the multiplication of blood cells by division in bird and mammalian embryos and on the division of muscle bundles in frog larvae. Since then I have continued these observations in frog larvae, where it is possible to follow the history of tissues back to segmentation.

The areas of the cortex responsible for attention and self-regulation develop in response to the emotional interaction with the person whom we may call the mothering figure. Usually this is the birth mother, but it may be another person, male or female, depending on circumstances. The right hemisphere of the mother’s brain, the side where our unconscious emotions reside, programs the infant’s right hemisphere. In the early months, the most important communications between mother and infant are unconscious ones. Incapable of deciphering the meaning of words, the infant receives messages that are purely emotional. They are conveyed by the mother’s gaze, her tone of voice and her body language, all of which reflect her unconscious internal emotional environment. Anything that threatens the mother’s emotional security may disrupt the developing electrical wiring and chemical supplies of the infant brain’s emotion-regulating and attention-allocating systems. Within minutes following birth, the mother’s odors stimulate the branching of millions of nerve cells in the newborn’s brain. A six-day-old infant can already distinguish the scent of his mother from that of other women. Later on, visual inputs associated with emotions gradually take over as the major influences. By two to seven weeks, the infant will orient toward the mother’s face in preference to a stranger‘s — and also in preference to the father’s, unless the father is the mothering adult. At seventeen weeks, the infant’s gaze follows the mother’s eyes more closely than her mouth movements, thus fixating on what has been called “the visible portion of the mother’s central nervous system.” The infant’s right brain reads the mother’s right brain during intense eye-to-eye mutual gaze interactions. As an article in Scientific American expressed it, “Embryologically and anatomically the eye is an extension of the brain; it is almost as if a portion of the brain were in plain sight.” The eyes communicate eloquently the mother’s unconscious emotional states.

The fact is that the individual, though its genotypic sex is fixed at fertilisation, can be profoundly affected by the environment in which it develops. In the ants, bees, and termites the larval nutrition determines whether the genotypic female individual will become a fully developed female (‘queen’) or a sexually retarded worker. In these cases the whole organism is affected; but the gonads do not play a part in establishing the sexual differences of the body, or soma. In the vertebrates, however, the hormones secreted by the gonads are the essential regulators. Numerous experiments show that by varying the hormonal (endocrine) situation, sex can be profoundly affected. Grafting and castration experiments on adult animals and man have contributed to the modern theory of sexuality, according to which the soma is in a way identical in male and female vertebrates. It may be regarded as a kind of neutral element upon which the influence of the gonad imposes the sexual characteristics. Some of the hormones secreted by the gonad act as stimulators, others as inhibitors. Even the genital tract itself is somatic, and embryological investigations show that it develops in the male or female direction from an indifferent and in some respects hermaphroditic condition under the hormonal influence. Intersexuality may result when the hormones are abnormal and hence neither one of the two sexual potentialities is exclusively realised.

The expression "fee thulumaatin thalaathin," translated into English as "a threefold darkness," indicates three dark regions involved during the development of the embryo. These are: a) The darkness of the abdomen b) The darkness of the womb c) The darkness of the placenta As we have seen, modern biology has revealed that the embryological development of the baby takes place in the manner revealed in the verse, in three dark regions. Moreover, advances in the science of embryology show that these regions consist of three layers each. The lateral abdominal wall comprises three layers: the external oblique, the internal oblique, and transverses abdominis muscles.91 Similarly, the wall of the womb also consists of three layers: the epimetrium, the myometrium and the endometrium.92 Similarly again, the placenta surrounding the embryo also consists of three layers: the amnion (the internal membrane around the foetus), the chorion (the middle amnion layer) and the decidua (outer amnion layer.)93 It is also pointed out in this verse that a human being is created in the mother's womb in three distinct stages. Indeed, modern biology has also revealed that the baby's embryological development takes place in three distinct regions in the mother's womb. Today, in all the embryology textbooks studied in departments of medicine, this subject is taken as an element of basic knowledge. For instance, in Basic Human Embryology, a fundamental reference text in the field of embryology, this fact is stated as follows: The life in the uterus has three stages: pre-embryonic; first two and a half weeks, embryonic; until the end of the eight week, and fetal; from the eight week to labor.

the scientific rulers will provide one kind of education for ordinary men and women, and another for those who are to become holders of scientific power. Ordinary men and women will be expected to be docile, industrious, punctual, thoughtless, and contented. Of these qualities, probably contentment will be considered the most important. In order to produce it, all the researches of psycho-analysis, behaviourism, and biochemistry will be brought into play…. All the boys and girls will learn from an early age to be what is called “co-operative”, i.e., to do exactly what everybody is doing. Initiative will be discouraged in these children, and insubordination, without being punished, will be scientifically trained out of them…. Except for the one matter of loyalty to the world State and to their own order, members of the governing class will be encouraged to be adventurous and full of initiative. It will be recognized that it is their business to improve scientific technique, and to keep the manual workers contented by means of continual new amusements…. In normal cases, children of sufficient heredity will be admitted to the governing class from the moment of conception. I start with this moment rather than birth since it is from this moment and not merely the moment of birth that the treatment of the two classes will be different. If, however, by the time the child reaches the age of three it is fairly clear that he does not attain the required standard, he will be degraded at that point. [T]here would be a very strong tendency for the governing classes to become hereditary, and that after a few generations not many children would be moved from either class into the other. This is especially likely to be the case if embryological methods of improving the breed are applied to the governing class, but not to the others. In this way the gulf between the two classes as regards native intelligence will become continually wider and wider…. Assuming that both kinds of breeding are scientifically carried out, there will come to be an increasing divergence between the two types, making them in the end almost different species. (pp. 181–188, emphasis added)

Every ritual repetition of the cosmogony is preceded by a symbolic retrogression to Chaos. In order to be created anew, the old world must first be annihilated. The various rites performed in connection with the New Year can be put in two chief categories: (I) those that signify the return to Chaos (e.g., extinguishing fires, expelling 'evil' and sins, reversal of habitual behavior, orgies, return of the dead); (2) those that symbolize the cosmogony (e.g., lighting new fires, departure of the dead, repetition of the acts by which the Gods created the world, solemn prediction of the weather for the ensuing year). In the scenario of initiatory rites, 'death' corresponds to the temporary return to Chaos; hence it is the paradigmatic expression of the end of a mode of being the mode of ignorance and of the child's irresponsibility. Initiatory death provides the clean slate on which will be written the successive revelations whose end is the formation of a new man. We shall later describe the different modalities of birth to a new, spiritual life. But now we must note that this new life is conceived as the true human existence, for it is open to the values of spirit. What is understood by the generic term 'culture,' comprising all the values of spirit, is accessible only to those who have been initiated. Hence participation in spiritual life is made possible by virtue of the religious experiences released during initiation. All the rites of rebirth or resurrection, and the symbols that they imply, indicate that the novice has attained to another mode of existence, inaccessible to those who have not undergone the initiatory ordeals, who have not tasted death. We must note this characteristic of the archaic mentality: the belief that a state cannot be changed without first being annihilated-in the present instance, without the child's dying to childhood. It is impossible to exaggerate the importance of this obsession with beginnings, which, in sum, is the obsession with the absolute beginning, the cosmogony. For a thing to be well done, it must be done as it was done the first time. But the first time, the thing-this class of objects, this animal, this particular behavior-did not exist: when, in the beginning, this object, this animal, this institution, came into existence, it was as if, through the power of the Gods, being arose from nonbeing. Initiatory death is indispensable for the beginning of spiritual life. Its function must be understood in relation to what it prepares: birth to a higher mode of being. As we shall see farther on, initiatory death is often symbolized, for example, by darkness, by cosmic night, by the telluric womb, the hut, the belly of a monster. All these images express regression to a preformal state, to a latent mode of being (complementary to the precosmogonic Chaos), rather than total annihilation (in the sense in which, for example, a member of the modern societies conceives death). These images and symbols of ritual death are inextricably connected with germination, with embryology; they already indicate a new life in course of preparation. Obviously, as we shall show later, there are other valuations of initiatory death-for example, joining the company of the dead and the Ancestors. But here again we can discern the same symbolism of the beginning: the beginning of spiritual life, made possible in this case by a meeting with spirits. For archaic thought, then, man is made-he does not make himself all by himself. It is the old initiates, the spiritual masters, who make him. But these masters apply what was revealed to them at the beginning of Time by the Supernatural Beings. They are only the representatives of those Beings; indeed, in many cases they incarnate them. This is as much as to say that in order to become a man, it is necessary to resemble a mythical model.

Primer of Love [Lesson 18] The biogenetic law or embryological parallelism, can be expressed as ' ontogeny recapitulatesphylogeny' states that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the evolution of their remote ancestors." ~ Ernst Haeckel Lesson 18) Love recapitulates the stages of a living organism. Love goes from dependent infancy, to adventurous childhood, to teenage turmoil, to mature adulthood -- which entails the entire repertoire of human emotion. Love gone awry leads to senility and death. Keep it on track and you have eternity.

The heart starts functioning at the end of the third week of intrauterine life (IUL), i.e., on day 22.

partial type

Subspecialty : Botany Studies : plants Subspecialty : Zoology Studies : animals Subspecialty : Marine biology Studies : organisms living in and around oceans, and seas Subspecialty : Fresh water biology Studies : organisms living in and around freshwater lakes, streams, rivers, ponds, etc. Subspecialty : Microbiology Studies : microorganisms Subspecialty : Bacteriology Studies : bacteria Subspecialty : Virology Studies : viruses ( see Figure below ) Subspecialty : Entomology Studies : insects Subspecialty : Taxonomy Studies : the classification of organisms Subspecialty : Studies : Life Science : Cell biology What it Examines : cells and their structures (see Figure below ) Life Science : Anatomy What it Examines : the structures of animals Life Science : Morphology What it Examines : the form and structure of living organisms Life Science : Physiology What it Examines : the physical and chemical functions of tissues and organs Life Science : Immunology What it Examines : the mechanisms inside organisms that protect them from disease and infection Life Science : Neuroscience What it Examines : the nervous system Life Science : Developmental biology and embryology What it Examines : the growth and development of plants and animals Life Science : Genetics What it Examines : the genetic make up of all living organisms (heredity) Life Science : Biochemistry What it Examines : the chemistry of living organisms Life Science : Molecular biology What it Examines : biology at the molecular level Life Science : Epidemiology What it Examines : how diseases arise and spread Life Science : What it Examines : Life Science : Ecology What it Examines : how various organisms interact with their environments Life Science : Biogeography What it Examines : the distribution of living organisms (see Figure below ) Life Science : Population biology What it Examines : the biodiversity, evolution, and environmental biology of populations of organisms Life Science : What it Examines :

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Fig. 3.7 The cell polarity model of differentiation of blastomeres. A, If the plane of cleavage of a blastomere is perpendicular to the surface of the embryo, each daughter cell becomes trophoblast. B, If the plane of cleavage is parallel to the surface, the daughter blastomere located at the surface becomes trophoblast, whereas the daughter cell located on the interior becomes part of the inner cell mass. Even though by the 16-cell stage the

Experimental evidence suggests that a key element underlying a daughter cell's becoming an outer cell is inheritance of a patch of outer cell membrane containing microvilli and the actin microfilament-stabilizing protein, ezrin. The proteins that produce polarity in the outer cells are postulated to direct their differentiation toward the trophoblastic lineage. Common to the inside-outside hypothesis and the cell polarity model is the recognition that a cell that does not contact the surface does not differentiate into trophoblast, but rather becomes part of the inner cell mass.

The polarized outer cells are destined to become trophoblast, whereas those cells located in the interior are destined to become the inner cell mass, from

stem

The common embryological origin of the endothelium and blood cells perhaps explains why many cytokines that control hematopoiesis are released by the vascular endothelium.

the molecular-anatomical-embryological phylogeny of the animal kingdom (fig. 5.7) links mollusks and annelids; we have transitional forms, both fossil and living, between these two phyla. It also links nematodes and arthropods, and we have transitional forms, both fossil and living, between these two phyla as well. Using Hox genes, we can demonstrate how radical changes in body plans are controlled by relatively simple genetic mechanisms and allow macroevolutionary changes to take place.

In the same way that Firestone’s embrace of scientific and technological progress as manifest destiny tips its hat to Marx and Engels, so also it resembles (perhaps even more closely) the Marxist-inspired biofuturism of the interwar period, particularly in Britain, in the work of writers such as H. G. Wells, J. B. S. Haldane, J. D. Bernal, Julian Huxley, Conrad Waddington, and their contemporaries (including Gregory Bateson and Joseph Needham, the latter of whose embryological interests led to his enduring fascination with the history of technology in China). Interestingly, it is also in these early twentieth century writings that ideas about artificial reproduction, cybernation, space travel, genetic modification, and ectogenesis abound. As cultural theorist Susan Squier has demonstrated, debates about ectogenesis were crucial to both the scientific ambitions and futuristic narratives of many of the United Kingdom’s most eminent biologists from the 1920s and the 1930s onward. As John Burdon Sanderson (“Jack”) Haldane speculated in his famous 1923 paper “Daedalus, or Science and the Future” (originally read to the Heretics society in Cambridge) ectogenesis could provide a more efficient and rational basis for human reproduction in the future: [W]e can take an ovary from a woman, and keep it growing in a suitable fluid for as long as twenty years, producing a fresh ovum each month, of which 90 per cent can be fertilized, and the embryos grown successfully for nine months, and then brought out into the air.

He shook hands, invited us in, accepted our gifts of food and beer, then told us it was fine with him if we camped in his garden for a few days. He spoke good English, with just the trace of a central European accent. When we arrived, he was sitting at a homemade desk on a tree-stump chair. The book he was reading was about the structure of the cell. He wanted to learn about cells, he said, to better understand embryology, which he was studying because he felt that somewhere along the evolutionary line, mankind had lost track of the proper meaning of life.

Haeckel had stirred such interest in embryology that he sowed the seeds for his own downfall. Eager to find evolutionary history in embryos, scientists studied embryonic development in diverse species. For the most part, von Baer’s idea of a similarity among embryos of different species held up, albeit with some exceptions. But the new data didn’t support Haeckel’s recapitulation theory; in fact, it did quite the opposite. At no stage of embryonic development could an ancestor be seen.

Ontogeny is a branch of embryology that studies how very dissimilar organisms look similar in the developmental stages (e.g., fish, frogs and people).

The female is nature’s default setting (embryology). All fetuses are female at the start but at about eight-weeks, a sudden surge of male hormones comes from the brain that kills all of the female attributes.

Evo Devo has not just provided a critical missing piece of the Modern Synthesis - embryology - and integrated it with molecular genetics and traditional elements such as paleontology. The wholly unexpected nature of some of its key discoveries and the unprecedented quality and depth of evidence it has provided toward settling previously unresolved questions bestow it with a revolutionary character.

The second group of beliefs, those relating to the generation of ores and stones in the belly of the earth - deserve particular attention. Rock engenders precious stones. The Sanskrit name for Emerald is, acmagarbhaja, 'born from rock', and the Indian minerological treatises describe its presence in the rock as being in its 'matrix'. The author of the Jawaher nameh (The Book of Precious Stones) distinguishes diamond from crystal by a difference in age expressed in embryological terms: the diamond is pakka, i.e. 'ripe', while the crystal is kaccha, 'not ripe' , 'green' , insufficiently developed.

Morphogenesis, the creation and mutation of forms, is “described by the disappearance of the attractors repre- senting the initial forms, and their replacement by capture*63 by the attractors representing the final forms.”⁴⁷ Concerning “attractors,” Thom admits, “little is known of the topological structure of structurally stable attractors. . . . It seems to me, however, that this is the essential geometric phenomenon intervening in a large number of morphogenetic processes, such as changes of phase in physics and the phenomenon of induction in embryology.

cell is not a name for a thing but for a type of organization

The embryology of fate before the event is but an ethereal wish, gestating into existence only upon the conclusion. A construct about the past, fate only coagulates into physical form once the outcome has been determined. Only looking backwards from the cozy confines of the future can destiny materialize to be dispensed as an explanation—a fallacious attempt at justification—righteous rationalization for the victor and feeble crutch for the defeated.

What is much less clear is the role of embryological mechanisms in evolution, and how they might contribute to species diversity.