Cytology in Dogs Cytology in Dogs Last Modified: August 02, 2015 Share This Article Read by: 141,681 pet lovers Cytology is the examination and study of blood or tissue cells under a microscope that can be done in dogs and other animals. Cytology can be used to detect inflammation, infection, bacteria, fungi, parasites and cancer. Cytology involves examination of a tissue or fluid sample. Often cytology is used to identify a lump or mass noted on physical examination. Certain skin diseases or hair loss situations – such as mange mite infection – can be diagnosed using cytology. Cytology is usually done when abnormal fluid is detected in a body cavity. Cytology may follow an abdominal ultrasound examination or surgical procedure that reveals abnormal organ tissue. Cytology of vaginal fluid can be used to guide breeding in female dogs. There is no real contraindication to performing this test. Negative results can exclude the presence of certain diseases. For example, a skin tumor might be malignant or benign. If the cytology shows the mass to be a simple fatty tumor, it may be left alone and followed.

In contrast, identification of a dangerous skin cancer, such as a mast cell tumor, would indicate the need for surgical removal of the mass. As with all tests, a cytologic examination is neither 100 percent sensitive nor specific. Should a cytology exam be negative or inconclusive, your veterinarian may recommend a full tissue biopsy sample be obtained and submitted for analysis. What Does Cytology Reveal in Dogs? Cytology can identify the presence of inflammation, infection, cancer, parasites, bacteria and fungi (molds and yeast). Following cytology, additional diagnostic tests, procedures, or medications may be recommended. How Is Cytology Done in Dogs? Cytology testing involves obtaining a sample of suspicious material. The material can be obtained by pressing a microscope slide against the tissue, by gently scraping the area with a scalpel blade, or by inserting a needle or sterile Q-tip into the tissue to obtain fluid or tissue. Once obtained, the material is spread thinly over a microscope slide and allowed to dry. Fluid samples may be placed in a centrifuge first to concentrate the cells before they are transferred to the slide. The sample is then dyed with special biological stains to ease identification of the cells. The sample is once again allowed to dry.

Once the dye has dried, the slide is ready for microscopic evaluation. Some veterinarians are sufficiently experienced to evaluate cytology specimens. Most veterinarians submit the cytology specimen to a diagnostic laboratory for evaluation by a veterinary pathologist. Even if your veterinarian provides you a presumptive diagnosis based on his/her evaluation of the slide, the final diagnosis is typically made after the pathologist reviews the sample. The cytology test generally takes 20 to 30 minutes to perform if done in the veterinarian's office. If the sample is submitted to a laboratory, results may not be available for 2 to 3 days. Is Cytology Painful to Dogs? In obtaining a sample with a needle, some pain may be involved, but very small needles typically are used. As with humans, the pain perceived from a needle stick varies among individual dogs, but it should not be any more painful than an injection or a blood sample. Is Sedation or Anesthesia Needed for Cytology? Sedation or anesthesia is not typically needed, but might be necessary depending on how the cytology sample is collected. Those samples obtained from skin scrapings or aspirations typically do not require sedation. Obviously, a sample obtained during a surgical procedure will require anesthesia for the surgery.

(?) Cynology - The Study of canines or domestic dogs Cynology You're browsing: Home » K9 Classroom » Cynology Cynology Article: General Information » Cynology Cynology (pron.: /sɨˈnɒlədʒi/) is the study of matters related to canines or domestic dogs. In English it may be a term sometimes used to denote serious zoological approach to the study of dogs[1] as well as by writers on canine subjects, dog breeders and trainers[2][3] and enthusiasts who informally study the dog,.[4][5] It is not a field of science, although the use of the Classical construction (linking of two Greek or Latin based words) in English is used to imply that it is a discipline or scientific. The word does not appear in standard English dictionaries. Etymology Cynology is a classical compound word (from Greek κύων, kyōn, genitive κυνός, kynos, “dog”; and -λογία, -logia) referring to the study of dogs. The word is not found in major English dictionaries and it is not a recognized scientific discipline in English-speaking countries.

Similar words are found in other languages, such German and Dutch kynologie, and the Russian кинология, from the Proto-Indo-European *ḱwon-, which is the source of hound. κυν is also the source of the English word cynic, and is directly related to canine and hound. Usage in English The suffix ‘-logy’ in English words refers to a study, or an academic discipline, or field of scientific study. English Classical compound words of this type may confer an impression of scientific rigor on a non-scientific occupation or profession. Usage in English of the word cynology is rare, and occasionally found in the names of dog training academies, with cynologist sometimes being used as a title by some dog trainers or handlers. People who informally study the dog may refer to themselves as ‘cynologists’ to imply serious study or scientific work.

The study of dogs Studies of dogs, and dog related matters, are carried out and published: in general, by those who have mastered the relevant literature or aspects of it, and the formal structure of the subject (National and International Kennel Club breeding, health, and show regulations etc); in specific, by biologists, geneticists, zoologists, behaviorists, and others scientists, historians, veterinarians and breed specialists. Informally, dogs may be studied by those with no specific scientific training, such as publicists and authors, breeders, trainers, police dog handlers, animal communicators and others, through literature, history,and personal experience. Many useful books and videotapes for the public have been produced through informal study of the dog. Those who, very rarely, refer to themselves as “cynologists”, may formally or informally study such things as veterinary science, dog breeding, breed development, dog behavior and training, and the literature and history of dogs. Usage in other languages Cynology, may have other connotations or use in languages other than English, see German de:Kynologie, Dutch nl:Kynologie and Czech cs:Sportovní kynologie.

The very rare term cynologist in English, is generally found to refer to “canine specialists” such as; certified care professionals, certified show judges, breeders, breed enthusiasts, certified dog-trainers and professional dog-handlers. A similar word is used to refer to dog handlers and dog trainers in Russia.[6][7] A veterinary clinic in Armenia offers a ‘cynologist’ to assist with dog training.[8] A magazine in the Baltic states described as ‘dedicated to the development of cynology in the Baltic countries’ covers dog training, dog shows, and veterinary advice (a hobbyist magazine, not a scientific journal.)[9] Notes and references Ology List - Sciences and Scientific Disciplines Also a science, chemistry is not an "ology". Chemistry is the study of matter and how it interacts with other matter and with energy. Mike Kemp, Getty Images Updated November 12, 2015. An ology is a discipline of study, as indicated by having the -ology suffix. This is a list of science ologies. Please let me know if you know of an -ology that should be added to the list.

Acarology, the study of ticks and mites Actinobiology, the study of the effects of radiation upon living organisms Actinology, the study of the effect of light on chemicals Aerobiology, a branch of biology that studies organic particles that are transported by the air Aerology, the study of the atmosphere Aetiology, the medical study of the causation of disease Agrobiology, the study of plant nutrition and growth in relation to soil Agrology, the branch of soil science dealing with the production of crops.

Agrostology, the study of grasses Algology, the study of algae Allergology, the study of the causes and treatment of allergies Andrology, the study of male health Anesthesiology, the study of anesthesia and anesthetics Angiology, the study of the anatomy of blood and lymph vascular systems Anthropology, the study of humans Apiology, the study of bees Arachnology, the study of spiders Archaeology, the study of past cultures Archaeozoology, the study of relationships between humans and animals over time Areology, the study of Mars Astacology, the study of crawfish Astrobiology, the study of origin of life Astrogeology, the study of geology of celestial bodies Audiology, the study of hearing Autecology, the study of the ecology of any individual species Bacteriology, the study of bacteria Bioecology, the study of interaction of life in the environment Biology, the study of life Bromatology, the study of food Cardiology, the study of the heart Cariology, the study of cells Cetology, the study of cetaceans (e.g., whales, dolphins) Climatology, the study of the climate Coleopterology, the study of beetles Conchology,

 the study of shells and of molluscs Coniology, the study of dust in the atmosphere and its effects on living organisms Craniology, the study of the characteristics of the skull Criminology, the scientific study of crime Cryology, the study of very low temperatures and related phenomena Cynology, the study of dogs Cytology, the study of cells Cytomorphology, the study of the structure of cells Cytopathology, the branch of pathology that studies diseases on the cellular level Dendrochronology, the study of the age of trees and the records in their rings Dendrology, the study of trees Dermatology, the study of the skin Dermatopathology, the field of dermatological anatomical pathology Desmology, the study of ligaments Diabetology, the study of diabetes mellitus Dipterology, the study of flies Ecohydrology, the study of interactions between organisms and the water cycle Ecology, the study of the relationships between living organisms and their environment Ecophysiology, the study of the interrelationship between an organism's physical functioning and its environment Edaphology, a branch of soil science that studies the influence of soil on life Electrophysiology, the study of the relationship between electric phenomena and

 bodily processes Embryology, the study of embryos Endocrinology, the study of internal secretory glands Entomology, the study of insects Enzymology, the study of enzymes Epidemiology, the study of the origin and spread of diseases Ethology, the study of animal behavior Exobiology, the study of life in outer space Exogeology, the study of geology of celestial bodies Prev morphology | Definition and examples | Britannica.com Alexander Braun Morphology, in biology , the study of the size, shape, and structure of animals , plants , and microorganisms and of the relationships of the parts comprising them.

The term refers to the general aspects of biological form and arrangement of the parts of a plant or an animal. The term anatomy also refers to the study of biological structure but usually suggests study of the details of either gross or microscopic structure. In practice, however, the two terms are used almost synonymously. Common leaf morphologies. Encyclopædia Britannica, Inc. Typically, morphology is contrasted with physiology , which deals with studies of the functions of organisms and their parts; function and structure are so closely interrelated, however, that their separation is somewhat artificial. Morphologists were originally concerned with the bones, muscles, blood vessels, and nerves comprising the bodies of animals and the roots, stems, leaves, and flower parts comprising the bodies of higher plants. The development of the light microscope made possible the examination of some structural details of individual tissues and single cells; the development of the electron microscope and of methods for preparing ultrathin sections of tissues created an entirely new aspect of morphology—that involving the detailed structure of cells. Electron microscopy has gradually revealed the amazing complexity of the many structures comprising the cells of plants and animals.

Other physical techniques have permitted biologists to investigate the morphology of complex molecules such as hemoglobin, the gas-carrying protein of blood, and deoxyribonucleic acid (DNA), of which most genes are composed. Thus, morphology encompasses the study of biological structures over a tremendous range of sizes, from the macroscopic to the molecular. A thorough knowledge of structure (morphology) is of fundamental importance to the physician, to the veterinarian, and to the plant pathologist, all of whom are concerned with the kinds and causes of the structural changes that result from specific diseases. Historical background toxicology Evidence that prehistoric man appreciated the form and structure of his contemporary animals has survived in the form of paintings on the walls of caves in France, Spain, and elsewhere. During the early civilizations of China, Egypt, and the Near East , as man learned to domesticate certain animals and to cultivate many fruits and grains, he also acquired knowledge about the structures of various plants and animals. Aristotle was interested in biological form and structure, and his Historia animalium contains excellent descriptions, clearly recognizable in extant species , of the animals of Greece and Asia Minor .

He was also interested in developmental morphology and studied the development of chicks before hatching and the breeding methods of sharks and bees. Galen was among the first to dissect animals and to make careful records of his observations of internal structures. His descriptions of the human body, though they remained the unquestioned authority for more than 1,000 years, contained some remarkable errors, for they were based on dissections of pigs and monkeys rather than of humans. Although it is difficult to pinpoint the emergence of modern morphology as a science , one of the early landmarks was the publication in 1543 of De humani corporis fabrica by Andreas Vesalius , whose careful dissections of human bodies and accurate drawings of his observations revealed many of the inaccuracies in Galen’s earlier descriptions of the human body. In 1661 an Italian physiologist, Marcello Malpighi , the founder of microscopic anatomy, demonstrated the presence of the small blood vessels called capillaries, which connect arteries and veins. The existence of capillaries had been postulated 30 years earlier by the English physician William Harvey , whose classic experiments on the direction of blood flow in arteries and veins indicated that minute connections must exist between them.

Between 1668 and 1680, the Dutch microscopist Antonie van Leeuwenhoek used the recently invented microscope to describe red blood cells, human sperm cells, bacteria, protozoans, and various other structures. Biology Bonanza Cellular components—the nucleus and nucleolus of plant cells and the chromosomes within the nucleus—and the complex sequence of nuclear events (mitosis) that occur during cell division were described by various scientists throughout the 19th century. Organographie der Pflanzen (1898–1901; Organography of Plants, 1900–05), the great work of a German botanist, Karl von Goebel , who was associated with morphology in all its aspects, remains a classic in the field. The Scot John Hunter and the Frenchman Georges Cuvier were early 19th-century pioneers in the study of similar structures in different animals—i.e., comparative morphology. Cuvier in particular was among the first to study the structures of both fossils and living organisms and is credited with founding the science of paleontology .

A British biologist, Sir Richard Owen , developed two concepts of basic importance in comparative morphology—homology, which refers to intrinsic structural similarity, and analogy , which refers to superficial functional similarity. Although the concepts antedate the Darwinian view of evolution , the anatomical data on which they were based became, largely as a result of the work of the German comparative anatomist Carl Gegenbaur, important evidence in favour of evolutionary change, despite Owen’s steady unwillingness to accept the view of diversification of life from a common origin. Britannica Stories Ringling Bros. Folds Its Tent One of the major thrusts in contemporary morphology has been the elucidation of the molecular basis of cellular structure. Techniques such as electron microscopy have revealed the complex details of cell structure, provided a basis for relating structural details to the particular functions of the cell, and shown that certain cellular components occur in a variety of tissues. Studies of the smallest components of cells have clarified the structural basis not only for the contraction of muscle cells but also for the motility of the tail of the sperm cell and the hairlike projections (cilia and flagella) found on protozoans and other cells.

Studies involving the structural details of plant cells, although begun somewhat later than those concerned with animal cells, have revealed fascinating facts about such important structures as the chloroplasts, which contain chlorophyll that functions in photosynthesis. Attention has also been focussed on the plant tissues composed of cells that retain their power to divide (meristems), particularly at the tips of stems, and their relationship with the new parts to which they give rise. The structural details of bacteria and blue-green algae, which are similar to each other in many respects but markedly different from both higher plants and animals, have been studied in an attempt to determine their origin. Connect with Britannica Facebook Twitter YouTube Instagram Pinterest Morphology continues to be of importance in taxonomy because morphological features characteristic of a particular species are used to identify it. As biologists have begun to devote more attention to ecology , the identification of plant and animal species present in an area and perhaps changing in numbers in response to environmental changes has become increasingly significant. Fundamental concepts Homology and analogy Homologous structures develop from similar embryonic substances and thus have similar basic structural and developmental patterns, reflecting common genetic endowments and evolutionary relationships.

In marked contrast, analogous structures are superficially similar and serve similar functions but have quite different structural and developmental patterns. The arm of a man, the wing of a bird, and the pectoral fins of a whale are homologous structures in that all have similar patterns of bones, muscles, nerves, blood vessels, and similar embryonic origins; each, however, has a different function. The wings of birds and those of butterflies, in contrast, are analogous structures—i.e., both allow flight but have no developmental processes in common. Organisms that have evolved along different paths may have analogous structures—that is, … Encyclopædia Britannica, Inc. The terms homology and analogy are also applied to the molecular structures of cellular constituents . Because the hemoglobin molecules from different vertebrate species contain remarkably similar sequences of amino acids, they may be termed homologous molecules. In contrast, hemoglobin and hemocyanin, the latter of which is present in crab blood, are termed analogous molecules because they have a similar function (oxygen transport) but differ considerably in molecular structure.

Corresponding similarities occur in the structures of other proteins from different species—e.g., cytochrome c and other enzymes (biological catalysts) such as the lactic dehydrogenases in birds and mammals. Body plan and symmetry The bodies of most animals and plants are organized according to one of three types of symmetry: spherical, radial, or bilateral. A spherically symmetrical body is similar throughout and can be cut in any plane through the centre to yield two equal halves. A few of the simplest plants and animals are spherically symmetrical—e.g., protozoans such as Radiolaria and Heliozoia. Radially symmetrical bodies, such as those of starfishes and mushrooms, have a distinguishable top and bottom and usually have a cylindrical shape, with the body parts radiating from the central axis. A starfish can be cut into two equal halves by any plane that includes the line, or axis, running through its centre from top to bottom. The anterior, or oral, end usually contains the mouth; a posterior, or aboral, end may have an anus.

In the bilaterally symmetrical body of higher animals including man, only a cut from head to foot exactly in the centre divides the body into equivalent halves. An anterior, or head, end and a posterior, or tail, end can be distinguished; and the dorsal, or back, side can be distinguished from the ventral, or belly, side. But because some internal organs of man are not symmetrical (e.g., the heart), even the right and left halves of the human body are not exactly equivalent. A few organisms—amoebas, slime molds, and certain sponges—with an irregular form, or one that changes as the organism moves, have no plane of symmetry. Morphological basis of classification Eyjafjallajökull volcano Like animals, plants may be either single celled or composed of many kinds of specialized cells. The bodies of most of the lower plants, such as algae and fungi, are comprised of the least differentiated and least specialized type of plant cells, parenchyma cells. The embryonic tissues of higher plants, unlike those of animals, remain extremely active throughout the life of the plant.

In addition, the different types of cells characteristic of the body of higher plants arise from meristems, specific regions in the plant body where cells divide and enlarge. In all but the simplest forms, the plant body is composed of various types of cells associated in more or less definite ways to form systems of units called tissue systems—e.g., the vascular system consisting of conductive tissues. The arrangement of the components of the vascular system is a distinguishing morphological feature of various plant groups. The character and relative extent of the two phases in the life history of a plant—the sexual phase, or gametophyte, and the sporophyte—vary considerably among the plant groups and are useful in distinguishing them. Areas of study Anatomy The best known aspect of morphology, usually called anatomy, is the study of gross structure, or form, of organs and organisms. It should not be inferred however, that even the human body, which has been extensively studied, has been so completely explored that nothing remains to be discovered.

It was found only in 1965, for example, that the nerve to the pineal gland, which lies on the upper surface of the brain of mammals, is a branch from the sympathetic nerves; the sympathetic nerves receive nerve impulses from a small branch of the nerves that transmit impulses from the eye to the brain (optic nerves). Thus the pineal gland responds by a very indirect route to quantitative changes in the environmental lighting and secretes appropriate amounts of the substance it forms, the hormone melatonin. Detailed comparisons of the morphological features of different animals, termed comparative anatomy , provide strong arguments for the evolutionary relationships among different species. In the course of evolution, animals and plants tend to undergo adaptive morphological changes that enable them to survive under certain environmental conditions. As a result, animals only remotely related evolutionarily may come to resemble each other superficially because of common adaptations to similar environments , a phenomenon known as convergent evolution .

Structural similarities—streamlined shape, dorsal fins, tail fins, and flipper-like forelimbs and hindlimbs, for example—have evolved in such varied animal groups as the dolphins and porpoises, both of which are mammals ; the extinct ichthyosaurs, which were reptiles; and both the bony and cartilaginous fishes. In a like manner, the mole, an insectivore, and the gopher, a rodent, have both evolved shovellike forelimbs, an adaptation for digging. An opposite phenomenon, divergent evolution, occurs when animals originally closely related adapt to different environments and come to be superficially quite different. Although sea lions and seals, for example, are carnivores and thus closely related to bears, cats, and dogs, their adaptations to an aquatic existence have resulted in morphological characteristics distinct from those of the terrestrial carnivores. In the course of mammalian evolution, many features have changed to permit specific animal groups to adapt to particular environments—e.g., the number and shape of the teeth, the length and number of bones in the limbs, the number and attachment sites of muscles, the thickness and colour of the hair or fur, and the length and shape of the tail.

Careful study of adaptive morphological aspects has permitted inferences about the course of the evolutionary history of various animals and of their successive adaptations to changing environments. The present-day Australian tree-climbing kangaroos , for example, are the descendents of a ground-dwelling marsupial , from whom evolved forms that began to live in trees and eventually developed limbs adapted to tree climbing. But the events may have occurred in the reverse sequence; that is, specialized limbs may have evolved before the animal adopted an arboreal mode of life. In any event, some of the tree-dwelling kangaroos subsequently left the trees, became readapted to life on the ground (i.e., their hindlegs became adapted for leaping), and then went back to the trees but with legs so highly specialized for leaping as to be useless in grasping a tree trunk; consequently, present-day tree kangaroos climb by bracing their feet against a tree trunk, as do bears. Careful comparisons of the feet of the many kinds of living Australian marsupials reveal the stages in this complicated process of adaptation and re-adaptation.

Changes in genes (mutations) constantly occur and may cause a decrease in size and function of an organ; on the other hand, a change in the environment or in the mode of life of a species may make an organ unnecessary for survival. As a result, many plants and animals contain organs or parts of organs that are useless, degenerate, undersized, or lacking some essential part when compared to homologous structures in related organisms. The human body, for instance, has more than 100 such organs—e.g., the appendix, the fused tail vertebrae (coccyx), the wisdom teeth, the muscles that wiggle the ears, and the hair on the body. The parts of a seed plant include roots, stems, leaves, and reproductive organs in the flowers. The evolution of specialized conducting tissues called xylem and phloem has enabled seed plants to survive on land and to attain large sizes. Roots anchor the plant; enable it to maintain an upright position; and absorb water, minerals, and other nutrients from the soil. The roots of plants such as carrots, beets, and yams serve as sites for food storage.

The stem links the roots with the leaves, where photosynthesis occurs, and its xylem and phloem are continuous with those of root and leaf. The stem supports leaves, flowers, and fruits. Each year, the stems of woody plants add a layer of xylem and phloem, the annual ring, the width of which varies with climatic conditions. A leaf consists of a petiole (stalk), by which it is attached to the stem, and a blade, typically broad and flat, that contains bundles, or veins, of xylem and phloem on the undersurface. The flower contains pollen-producing anthers and egg-producing ovules. After fertilization the base of the flower, or ovary, enlarges and forms the fruit, which is a mature ovary containing seeds, or mature ovules. The bodies of ferns and mosses also are composed of roots, stems, and leaves, but those of lower plants such as mushrooms and kelps are much more simple and lack true roots, stems, and leaves. Histology A major trend in the evolution of both plants and animals has resulted in the specialization of cells and a division of labour among them.

The cells comprising a tree or a man are quite different; each is specialized to carry out certain functions. Although specialization may permit a cell to function efficiently, it also increases the interdependence of body parts; an injury to or the destruction of one part, therefore, may result in death of the whole organism. The study of the structure and arrangement of tissues , defined as groups or layers of cells that together perform certain special functions, is termed histology. Each kind of tissue is composed of cells with characteristic features such as size, shape, and relationship to adjacent cells and may also contain noncellular material—connective tissue fibres or a bony material. Morphologists usually separate animal tissues into six groups; epithelial , connective , muscular, blood, nervous, and reproductive tissues. The cells composing epithelial tissues form a continuous layer or sheet that either covers the surface of the body or lines some cavity within the body, thus protecting the underlying cells from mechanical and chemical injury or from invasion by microorganisms. Epithelial tissues absorb nutrients and water, secrete a wide variety of substances, and may play a role in the reception of sensory stimuli.

The connective tissues—bone, cartilage, ligaments, and fibrous connective tissue—support and hold together the other cells of the body. The cells of the connective tissues secrete large quantities of nonliving material (matrix), the characteristics of which largely determine the nature and the function of the specific types of connective tissue; the matrix secreted by fibrous connective tissue cells, for example, is a thick matted network of microscopic fibres surrounding the connective tissue cells. Connective tissue holds skin to muscle, keeps glands in position, makes up the tough outer walls of the blood vessels, and forms a sheath around nerve fibres and muscle cells. Tendons are flexible, cable-like cords of specialized fibrous connective tissue that join muscles to each other or muscle to bone. Ligaments are somewhat elastic cords of specialized fibrous connective tissue that join one bone to another. Muscular tissues are composed of elongated, cylindrical, or spindle-shaped cells, each of which contains many small fibres called myofibrils. Muscle cells perform mechanical work by contracting—that is, by becoming shorter and thicker.

The three types of vertebrate muscles include the cardiac muscle, which is found only in the walls of the heart; smooth muscles, which are found in the walls of the digestive tract and in other internal organs; and skeletal muscles, which make up the bulk of the muscle masses attached to the bones of the body. Skeletal and cardiac muscles have alternating light and dark stripes the relative sizes of which change during the contraction process. Evidence from electron microscopy indicates that two types of filaments occur in muscle; during contraction, one type of filament slides past the other. Nerve tissue is made of cells, called neurons , which are specialized to conduct nerve impulses. Two or more thin hairlike fibres, called axons and dendrites, extend from the enlarged cell body containing the nucleus. The neurons extending from the spinal cord to the end of an appendage (e.g., arm, leg) may extend to a metre (about three feet) or more in man and to several metres in an elephant or a whale. Egg cells in the female and sperm cells in the male are reproductive tissues adapted for the production of offspring. The egg cell is modified by the accumulation of considerable amounts of yolk and other food reserves.

The highly specialized spermatozoon contains a tail, the beating of which propels it to the egg. Blood is composed of red cells, which are specialized for the transport of oxygen and carbon dioxide, and white cells, which engulf bacteria and produce antibodies (proteins formed in response to foreign substances called antigens). Blood also contains platelets, small fragments of cells from the bone marrow that play a key role in initiating the clotting of blood. The cells of higher plants may be differentiated into meristematic, protective, fundamental, and conductive tissues. Meristematic tissues, which are composed of small, thin-walled cells with few or no vacuoles (cavities), differentiate into the other types of plant tissue and are found in the rapidly growing parts of the plant—e.g., at the tips of roots and stems. Protective tissues are composed of thick-walled cells that protect the underlying thin-walled cells from mechanical abrasion and dehydration; examples of protective tissues include the epidermis of leaves and the cork layers of stems and roots.

The fundamental tissues comprising the body of a plant include the soft parts of the leaf, the components of the pith and the cortex of stems, the roots, and the soft parts of flowers and fruits. These tissues function in the production and storage of food. Two types of conductive tissues occur in higher plants: xylem conducts water and dissolved salts, and phloem conducts dissolved organic materials such as sugars. Both types are composed of elongated cells that fuse end to end with other cells to form the sieve tubes through which substances are transported in phloem and xylem vessels. Cytology The living material of most organisms is organized into discrete units termed cells ; the study of their features is known as cytology. The cellular contents, when viewed through a microscope at low magnification, usually appear to consist of granules or fibrils of dense material, droplets of fatty substances, and fluid-filled vacuoles suspended in a clear, continuous, semifluid substance called cytoplasm.

The remarkable structural complexity of the cell is more fully revealed at the higher magnifications attainable with the electron microscope; structural details of various cellular components, or organelles, as revealed by the technique known as X-ray diffraction analysis, have provided information concerning the relationships between the structures of the cellular components and of the molecules comprising them. Although most cells have certain features in common, the kinds and amounts of components vary considerably. Cellular components include structures such as mitochondria, chloroplasts, endoplasmic reticulum, Golgi complex, lysosomes, oil droplets, granules, and fibrils. The membrane around the cell is a three-layered structure called a unit membrane; similar membranes surround many cellular components—e.g., the mitochondria. A small spherical or oval organelle, the nucleus , is typically found near the centre of a cell. The genes within the nucleus control the development of the various traits of the cell by controlling the synthesis of specific proteins. The nuclear components are separated from those of the cytoplasm by the nuclear membrane. The structure of the nucleolus, a spherical body within the nucleus, is extremely variable in most cells.

Although more than one nucleolus may occur in a nucleus, each cell of an animal or plant species has a fixed number of nucleoli. The nucleoli apparently play a role in the synthesis of the ribonucleic acid (RNA) constituent of the cellular components called ribosomes, which function in protein synthesis. Adjacent to the nucleus in the cells of animals and certain lower plants are two small, cylindrical bodies, the centrioles, which, during cell division, separate, migrate to opposite sides of the cell, and organize a structure called a spindle between them. Within the cytoplasm of both plant and animal cells are components called mitochondria, which may be shaped like spheres, rods, or threads. Each mitochondrion is bounded by a double membrane, the outer layer of which forms the smooth outer boundary of the mitochondrion; the inner layer, folded repeatedly into shelflike folds called cristae, contains enzymes that play an essential role in the conversion of the energy of foodstuffs into the energy used for cellular activities. The cells of most plants contain plastids , small bodies involved in the synthesis and storage of foodstuffs. The most important plastids, the chloroplasts, function in trapping the energy of sunlight during photosynthesis.

They are disk-shaped structures with a platelike arrangement of tightly stacked membranes. The cytoplasmic components important in protein synthesis, the ribosomes, are composed of nucleic acid and protein. Clusters of five or more ribosomes, termed polysomes, appear to be the functional unit in protein synthesis. Lysosomes are membrane-bound structures containing a variety of enzymes that can break down the large molecular constituents of the cell. The membrane surrounding lysosomes presumably prevents the enzymes from digesting the cell contents before the cell dies. Embryology The structures and the relationships among the various parts of a mature plant or animal are usually better understood if the successive developmental stages are studied. Thus, morphologists have traditionally been interested in the study of embryos and their developmental patterns—i.e., the science of embryology . Development typically begins in animals with the cleavage, or division, of the fertilized egg (zygote) to form a hollow ball of cells called the blastula; the blastula then develops into a hollow cuplike body of two layers of cells, the gastrula, from which the embryo ultimately is formed. At one time, the techniques available to embryologists enabled them to study only whole embryos at different developmental stages.

The science of experimental embryology began during the first half of the 20th century, when microsurgical techniques became available either for the removal and study of certain structures from tiny embryos or for their transplantation to other regions of the embryo. Advances in understanding the mechanism by which biological information is transferred in DNA and the means by which this information results in the production of specific proteins have led to efforts to describe development in biochemical terms. Although hypotheses regarding the reasons for the appearance of a specific enzyme or some other protein at a specific time during development have been formulated and tested, the biochemical basis of morphogenesis itself—that is, the reason for the development of particular structures—has not yet been established. The development of the seed plant is basically different from that of an animal. The egg cell of a seed plant is retained within the enlarged lower part, or ovary, of the seed-bearing organ (pistil) of a flower; two sperm nuclei pass through a structure called a pollen tube to reach the egg.

One sperm nucleus unites with the egg nucleus to form the zygote from which the new plant will develop; the second sperm nucleus unites with two nuclei, called polar nuclei, to form a body called a triploid endosperm, the cells of which divide to form a nutritive mass within the seed. The zygote undergoes several cell divisions to form the embryo, which is surrounded by the endosperm. The embryo develops one or two seed leaves, or cotyledons, which may become thick and fleshy with stored foodstuffs. The epicotyl, which consists of a growing point enclosed by a pair of folded miniature leaves, develops above the point of attachment of the seed leaves. Below the seed leaves extends the hypocotyl, the tip, or radicle, of which forms the primary root of the embryonic plant. The factors involved in initiating and controlling morphogenesis in plants have been studied by growing cells, tissues, and organs derived from plants. Indeed, an entire carrot plant has been grown from one cell of a mature carrot; this provides striking evidence that the cell from the adult plant contains all of the genetic information needed to produce an entire plant, including roots, stems, and leaves.

The technique of growing plants from isolated plant parts has been useful in studies involving the characteristics of embryonic growth, the correlated growth of plant parts, and the nature of differentiation and regeneration (the replacement of lost parts). Page 1 of 2

Question: Cynology is the study of which animals?
Answer: Dogs