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from article Animal virus
Electron micrograph of negatively stained, purified bovine papilloma virions with icosahedral symmetry. (Credit: David Hill and John P. Sundberg)
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from article Animal virus
Electron micrograph of a thin section of chicken cells containing crystalline inclusion bodies formed by an avian reovirus during infection. (Credit: David Hill and John P. Sundberg)
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from article Behavioral psychophysics
Diagram of the apparatus for measuring the pigeon's absolute visual threshold. (After D S. Blough, A method for obtaining psychophysical thresholds from the pigeon, J. Exp. Anal. Behav., 1:31–43, 1958)
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from article Tick virus diseases
A deer or black-legged tick (Ixodes scapularis). (Credit: U.S. Centers for Disease Control and Prevention)
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from article Tick virus diseases
Diagram depicting the life cycle of Ixodes scapularis. This deer tick can transmit viruses and other pathogens that cause a number of important diseases, including Lyme disease, anaplasmosis, and babesiosis. The risk of human infection is greatest…
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from article Tick virus diseases
World map depicting the locations of human tick-borne disease cases. Heartland, Bourbon, and Colorado tick fever virus cases are unique to North America. Powassan encephalitis cases are reported in North America and Russia. Tick-borne encephalitis…
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from article Tick virus diseases
Cases of Powassan encephalitis reported in the United States from 2006 to 2015. Most of the reported cases are in Minnesota, New York, and Wisconsin. (Credit: ArboNET, Arboviral Diseases Branch, U.S. Centers for Disease Control and Prevention)
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from article Anaerobic infection
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from article Degenerative neural diseases
Factors leading to degenerative neural diseases. Abbreviations: AD, Alzheimer's disease; AD/PD, Alzheimer's disease with parkinsonism; ALS, amyotrophic lateral sclerosis; DLB, dementia with Lewy bodies; FTD, frontotemporal dementia; MID,…
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from article Ergot and ergotism
Ergot life cycle. Parts a–d explained in text.
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from article Exotic viral diseases
A colorized negative stained transmission electron micrograph depicting a number of Marburg virus virions. Marburg virus disease is a rare, exotic viral disease that affects both humans and nonhuman primates. (Credit: Frederick A. Murphy/Centers for…
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from article Regular polytopes
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from article Regular polytopes
Two regular polyhedrons. (a) Dodecahedron {5,3}. (b) Icosahedron {3,5}.
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from article Regular polytopes
Two of the six regular four-dimensional polytopes. (a) The 5-cell {3,3,3}. (b) The 8-cell {4,3,3}.
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from article Analytic hierarchy
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from article Analytic hierarchy
Analytic hierarchy used to assist a family in buying a new car.
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Reproductive behavior
The mating of dragonflies encompasses a number of reproductive behaviors. Typically, the male is in front and the female is behind. If the female is willing to mate, she bends her abdomen forward to collect sperm from the male's accessory genitalia,…
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from article Reproductive behavior
Sage-grouse lek. Males stake out and defend territories on a traditional breeding ground. Females breed with males in selected territories. (Credit: U.S. Fish and Wildlife Service)
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from article Reproductive behavior
Two bull northern elephant seals fighting for dominance on the beach. (Credit: eoind/Getty Images)
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from article Reproductive behavior
Natterjack toad giving a mating call with its vocal sac expanded. (Credit: Bobby Bok)
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from article Reproductive behavior
Mating behavior of sticklebacks: (a) zigzag dance of a male, which leads a female to the nest; (b) the male stimulates the female in the nest to lay eggs; (c) schematic portrayal of the events in a courtship sequence. (Credit: Based on original…
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from article Reproductive behavior
Lordosis in a female rodent. When mounted, the females of many mammalian species adopt the lordotic posture, rendering copulation possible. Note the concave arching of the spine. (Credit: Based on an original drawing by L. C. Drickamer and S. H.…
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from article Reproductive behavior
A black-browed albatross feeding a chick. This is one example in which parental care may be extensive and prolonged. (Credit: Vetta/Getty Images)
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from article Toxin
Bacteria, such as Clostridium perfringens, often produce exotoxins that have deleterious effects on other organisms. Clostridium perfringens can cause foodborne disease by contamination of raw food materials. (Credit: Don Stalons/Centers for Disease…
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from article Toxin
Taiwan banded krait (Bungarus multicinctus). Certain elapid snakes known as kraits produce a venom that contains bungarotoxins, which are potent neurotoxins. (Credit: LiCheng Shih)
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from article Celiac disease
Small bowel biopsy showing villous atrophy, which is found in individuals affected by celiac disease. (Credit: Ed Uthman/National Institutes of Health)
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from article Celiac disease
Antigen presentation of gliadin peptide to a CD4 T cell. Gliadin peptides bind to pockets P1, P4, P6, P7, and P9 of the (a) HLA-DQ8 and (b) HLA-DQ2 molecules. (Copyright © McGraw-Hill Education)
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from article Concussion
A three-dimensional magnetic resonance imaging (MRI) view of a human brain. The red-colored areas indicate temporary injury to the brain's covering following a concussion. (Credit: Lawrence Latour, Center for Neuroscience and Regenerative Medicine,…
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from article Infertility
Illustration of (left) a normal ovary compared to (right) a polycystic ovary. A polycystic ovary can result from an imbalance of reproductive hormones. (Credit: Alila Medical Images)
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from article Infertility
Colored scanning electron micrograph of a deformed sperm cell. The cell has residual cytoplasm (denoted by the pinkish lump) below its head (top right). (Credit: Steve Gschmeissner/Science Photo Library/Alamy Stock Photo)
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from article Industrial health and safety
Woodworker wearing safety goggles and hearing protection. (Credit: Shutterstock/Robert Kneschke)
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from article Forensic dentistry
A dental identification from a homicide case. (a) Radiograph of the decedent exposed 18 years prior to her murder. (b) Radiograph of the decedent exposed 1 month prior to death. (c) Radiograph of the skeletal remains that were thought to be her.…
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from article Forensic dentistry
Four human bite marks on human skin. The American Board of Forensic Odontology (ABFO) #2 scale is present in each photograph to assist in documenting the size of the injury as well as the positioning of the camera. Bite (a) exhibits a higher degree…
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from article Rheumatic fever
Photomicrograph of Streptococcus pyogenes illustrates its chain structure. Streptococcus pyogenes stains purple/violet after undergoing a Gram stain test. (Credit: Lisa Burgess; copyright © McGraw Hill)
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from article Cleft lip and cleft palate
Unilateral, incomplete cleft lip in which the notch does not extend to the nose.
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from article Cleft lip and cleft palate
Cleft palate, resulting in a fissure in the palate connecting the nasal and oral cavities.
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from article Protein
Molecular model illustration of myoglobin, which is a protein found in the muscle tissue of mammals. Myoglobin is an important protein that binds to and stores oxygen for use during strenuous exercise. The structure of the globin protein protects…
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from article Protein
The levels of protein structure, including primary, secondary (α-helices and β-sheets), tertiary, and quaternary. (Copyright © McGraw-Hill Education)
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from article Protein
The α-helix of protein structure. The repeating NHCOC units form the backbone, which spirals up in a left-handed or right-handed fashion. (The right-handed configuration is adopted in natural proteins with l-amino acids.) Hydrogen bonds are…
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from article Protein
Illustration of the molecular structure of hemoglobin. A single molecule of hemoglobin is composed of four protein subunits, called globins, with each containing a heme group that holds a single iron ion in its center. (Copyright © McGraw-Hill…
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from article Ixodides
An argasid tick, Otobius megnini, known as the spinose ear tick, shown enlarged. (Photo by Mat Pound, Agricultural Research Service, U.S. Department of Agriculture)
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from article Ixodides
A female ixodid tick, Ixodes scapularis, known as the blacklegged tick or deer tick, shown enlarged. This tick spreads Lyme disease in the eastern half of the United States. (Photo by Scott Bauer, Agricultural Research Service, U.S. Department of…
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from article Myxozoa
Different types of myxospores, the typical myxozoan stage in the fish host. Top row: Species of the most species-rich myxozoan genus Myxobolus—M. aeglefini from the eye cornea of the gadoid fish Melanogrammus aeglefinus (left); Myxobolus species…
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from article Myxozoa
Life cycle of Myxozoa. The myxosporean life cycle involves an annelid definitive host and a vertebrate intermediate host. Actinospores are released from an annelid and typically infect a fish host. Myxospores are produced after the vast…
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from article Immunotherapy
Numerous points along the cancer immunity cycle are targeted by researchers in attempts at immunotherapy. In general, researchers seek to improve the ability of a tumor-bearing individual (the host) to reject the tumor immunologically. (Copyright ©…
