Illustration of a fetus in the uterus showing overt umbilical cord prolapse. Part of the umbilical cord protrudes past the fetus, through the cervix, and into the vagina. The fetal membranes have ruptured, and the fetus' body constricts the umbilical vessels (blood supply).

Illustration of the relationship between the oxytocin hormone and uterine muscle contraction duing labor. Both the mother and the fetus release oxytocin, which stimulates the uterine wall, initiating labor.

Illustration of a spinal tap showing the removal of cerebrospinal fluid (CSF) from the lumbar region of a patient's spine.

Illustration of a sputum collection device.

Trichomonas vaginalis, a sexually-transmitted parasite infecting the vagina. T. vaginalis uses cilia for propulsion and assumes an amoeba-like shape once it attaches to the vaginal epithelial cells (top). It triggers an inflammatory response: inducing neutrophil migration, the release of cytokines and antibodies, and the sloughing of epithelia (bottom).

Collage of tuberculosis imagery: illustration of macroscopic lesions of the lung parenchyma, also called tubercles or abscesses (far left and insets); an x-ray of tuberculous lungs (center top); and microscopic, rod-shaped tubercle bacilli the cause of tuberculosis (circular, background).

Type 2 diabetes and obesity: a possible link is resistin (green), a protein secreted by adipocytes (fat cells). Released into the bloodstream, resistin can modulate the insulin-signaling pathway in certain tissues (muscle, liver, etc.) by linking with receptors on membrane surfaces, thereby inducing resistance to insulin (transparent and white).

Illustration of insulin delivery systems relevant to diabetes. Recently improved transdermal insulin delivery systems, such as insulin pumps and insulin pens, enhance both the convenience and compliance of diabetes patients. Also shown are synthesis and secretion of insulin into the bloodstream by a pancreatic beta islet cell.

Diabetes collage, showing oral medications used in the treatment of childhood diabetes. Administered in convenient tablet form, some drugs help increase insulin production by acting on the surface receptor cells of beta islet cells, and some act to decrease hepatic glucose production or decrease intestinal absorption of glucose across the brush border.

Islet cell transplantation collage. In treating diabetes, pancreatic islet cells are harvested from a donor (human, pig, baboon, etc.) and injected into the portal vein of the recipient's liver. These cell clusters then lodge in branches of the portal vein and secrete insulin, which then enters the systemic circulation via the hepatic vein.

Normal (left) and inflamed bronchiole (right). Inflammatory response, as in asthma, is shown by hypertrophy, hyperplasia, and constriction of the airway's smooth muscle bands. Structural changes include blood vessel proliferation, denuded respiratory epithelium, deposition of submucosal collagen, mucous gland hypertrophy, and general edema (reduced lumen).

Aromatase inhibitors shown binding to aromatase (lower right), preventing the androgen substrate (red molecules) from binding and being converted to estradiol and estrone. This reduces the level of estrogen in the bloodstream of the breast cancer patient. Insets on left, top to bottom: adipose tissue, adrenal cortex, and breast tumor.

Sleep disorder collage. Highlighted is sleep apnea, the cessation of airflow, which results from airway restriction due to anatomical or neuromuscular factors. Vignettes and insets show (from top, clockwise) insomnia, EEG sleep stages, the hypothalamus (thought to affect the sleep cycle via optic nerve stimulus), somnograph breathing patterns, and PET scans.

Lyme disease cycle. Tick eggs become larvae and feed on small mammals or birds infected with the Lyme disease bacterium, Borrelia burgdorferi. Infected tick larvae then molt into nymphs over many months, emerging aggressively in spring to infect new hosts, including humans. The nymphs molt to become adult ticks, which seek new hosts, mate, and produce eggs.

Lyme disease cycle. Tick eggs become larvae and feed on small mammals or birds infected with the Lyme disease bacterium, Borrelia burgdorferi. Infected tick larvae then molt into nymphs, emerging aggressively in spring to infect new hosts, including humans. The nymphs molt to become adult ticks, which seek new hosts, mate, and produce eggs.

Arterial antiplatelet therapy drugs inhibit platelet aggregation on atherosclerotic plaque surfaces, thus preventing thrombus and embolus formation and vessel occlusion. ADP antagonists, e.g., clopidogrel and ticlopidine, inhibit ADP-mediated platelet aggregation and adhesion (left pathways and inset). Aspirin inhibits the cyclooxygenase pathway (right).

Venous anticoagulation (left) and arterial antiplatelet (right) drug therapies. Venous anticoagulation agents interfere with thrombin production and fibrin formation or inhibit the vitamin K dependent clotting factor synthesis. Arterial antiplatelet therapy drugs inhibit platelet aggregation, either as ADP antagonists or cyclooxygenase pathway inhibitors.

Illustration of the brain, showing a tumor (orange-red).

Illustration of laparoscopic urological surgery. Upper inset: polycystic kidney viewed laparoscopically, allowing the urologist to make a treatment assessment. Lower inset: partial nephrectomy (kidney removal) for the repair of defects in the collecting ducts. Left inset: closure after pyeloplasty due to an obstruction in the ureteropelvic junction.

Illustration of stent angioplasty. The stent, a tubular mesh prosthetic device, is inserted into the narrowed (stenotic) blood vessel to keep the vessel open and allow improved blood flow.