Adrenal Cortex
The outer layer of the adrenal gland. It is derived from MESODERM and comprised of three zones (outer ZONA GLOMERULOSA, middle ZONA FASCICULATA, and inner ZONA RETICULARIS) with each producing various steroids preferentially, such as ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE. Adrenal cortex function is regulated by pituitary ADRENOCORTICOTROPIN.
Adrenal Glands
A pair of glands located at the cranial pole of each of the two KIDNEYS. Each adrenal gland is composed of two distinct endocrine tissues with separate embryonic origins, the ADRENAL CORTEX producing STEROIDS and the ADRENAL MEDULLA producing NEUROTRANSMITTERS.
Adrenal Medulla
The inner portion of the adrenal gland. Derived from ECTODERM, adrenal medulla consists mainly of CHROMAFFIN CELLS that produces and stores a number of NEUROTRANSMITTERS, mainly adrenaline (EPINEPHRINE) and NOREPINEPHRINE. The activity of the adrenal medulla is regulated by the SYMPATHETIC NERVOUS SYSTEM.
Zona Reticularis
The inner zone of the adrenal cortex. This zone produces the enzymes that convert PREGNENOLONE, a 21-carbon steroid, to 19-carbon steroids (DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE) via 17-ALPHA-HYDROXYPREGNENOLONE.
Adrenal Gland Neoplasms
Tumors or cancer of the ADRENAL GLANDS.
Adrenal Gland Diseases
Pathological processes of the ADRENAL GLANDS.
Adrenocorticotropic Hormone
An anterior pituitary hormone that stimulates the ADRENAL CORTEX and its production of CORTICOSTEROIDS. ACTH is a 39-amino acid polypeptide of which the N-terminal 24-amino acid segment is identical in all species and contains the adrenocorticotrophic activity. Upon further tissue-specific processing, ACTH can yield ALPHA-MSH and corticotrophin-like intermediate lobe peptide (CLIP).
Zona Fasciculata
The wide middle zone of the adrenal cortex. This zone produces a series of enzymes that convert PREGNENOLONE to cortisol (HYDROCORTISONE) via 17-ALPHA-HYDROXYPROGESTERONE.
Cerebral Cortex
Adrenal Insufficiency
Conditions in which the production of adrenal CORTICOSTEROIDS falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the ADRENAL GLANDS, the PITUITARY GLAND, or the HYPOTHALAMUS.
Prefrontal Cortex
The rostral part of the frontal lobe, bounded by the inferior precentral fissure in humans, which receives projection fibers from the MEDIODORSAL NUCLEUS OF THE THALAMUS. The prefrontal cortex receives afferent fibers from numerous structures of the DIENCEPHALON; MESENCEPHALON; and LIMBIC SYSTEM as well as cortical afferents of visual, auditory, and somatic origin.
Visual Cortex
Zona Glomerulosa
The narrow subcapsular outer zone of the adrenal cortex. This zone produces a series of enzymes that convert PREGNENOLONE to ALDOSTERONE. The final steps involve three successive oxidations by CYTOCHROME P-450 CYP11B2.
Steroid 11-beta-Hydroxylase
A mitochondrial cytochrome P450 enzyme that catalyzes the 11-beta-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP11B1 gene, is important in the synthesis of CORTICOSTERONE and HYDROCORTISONE. Defects in CYP11B1 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).
Motor Cortex
Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.
Adrenocortical Adenoma
A benign neoplasm of the ADRENAL CORTEX. It is characterized by a well-defined nodular lesion, usually less than 2.5 cm. Most adrenocortical adenomas are nonfunctional. The functional ones are yellow and contain LIPIDS. Depending on the cell type or cortical zone involved, they may produce ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and/or ANDROSTENEDIONE.
Adrenal Cortex Function Tests
Adrenal Cortex Hormones
Adrenal cortex hormones are steroid hormones produced by the outer portion of the adrenal gland, consisting of glucocorticoids, mineralocorticoids, and androgens, which play crucial roles in various physiological processes such as metabolism regulation, stress response, electrolyte balance, and sexual development and function.
Adrenocortical Carcinoma
A malignant neoplasm of the ADRENAL CORTEX. Adrenocortical carcinomas are unencapsulated anaplastic (ANAPLASIA) masses sometimes exceeding 20 cm or 200 g. They are more likely to be functional than nonfunctional, and produce ADRENAL CORTEX HORMONES that may result in hypercortisolism (CUSHING SYNDROME); HYPERALDOSTERONISM; and/or VIRILISM.
Auditory Cortex
The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.
Adrenal Hyperplasia, Congenital
A group of inherited disorders of the ADRENAL GLANDS, caused by enzyme defects in the synthesis of cortisol (HYDROCORTISONE) and/or ALDOSTERONE leading to accumulation of precursors for ANDROGENS. Depending on the hormone imbalance, congenital adrenal hyperplasia can be classified as salt-wasting, hypertensive, virilizing, or feminizing. Defects in STEROID 21-HYDROXYLASE; STEROID 11-BETA-HYDROXYLASE; STEROID 17-ALPHA-HYDROXYLASE; 3-beta-hydroxysteroid dehydrogenase (3-HYDROXYSTEROID DEHYDROGENASES); TESTOSTERONE 5-ALPHA-REDUCTASE; or steroidogenic acute regulatory protein; among others, underlie these disorders.
Somatosensory Cortex
Area of the parietal lobe concerned with receiving sensations such as movement, pain, pressure, position, temperature, touch, and vibration. It lies posterior to the central sulcus.
Cosyntropin
A synthetic peptide that is identical to the 24-amino acid segment at the N-terminal of ADRENOCORTICOTROPIC HORMONE. ACTH (1-24), a segment similar in all species, contains the biological activity that stimulates production of CORTICOSTEROIDS in the ADRENAL CORTEX.
Aldosterone
Adrenalectomy
Excision of one or both adrenal glands. (From Dorland, 28th ed)
Adrenodoxin
An iron-sulfur protein which serves as an electron carrier in enzymatic steroid hydroxylation reactions in adrenal cortex mitochondria. The electron transport system which catalyzes this reaction consists of adrenodoxin reductase, NADP, adrenodoxin, and cytochrome P-450.
Hydrocortisone
Corticosterone
Aldosterone Synthase
A mitochondrial cytochrome P450 enzyme that catalyzes the 18-hydroxylation of steroids in the presence of molecular oxygen and NADPH-specific flavoprotein. This enzyme, encoded by CYP11B2 gene, is important in the conversion of CORTICOSTERONE to 18-hydroxycorticosterone and the subsequent conversion to ALDOSTERONE.
Cholesterol Side-Chain Cleavage Enzyme
A mitochondrial cytochrome P450 enzyme that catalyzes the side-chain cleavage of C27 cholesterol to C21 pregnenolone in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP11A1 gene, catalyzes the breakage between C20 and C22 which is the initial and rate-limiting step in the biosynthesis of various gonadal and adrenal steroid hormones.
Steroidogenic Factor 1
A transcription factor and member of the nuclear receptor family NR5 that is expressed throughout the adrenal and reproductive axes during development. It plays an important role in sexual differentiation, formation of primary steroidogenic tissues, and their functions in post-natal and adult life. It regulates the expression of key steroidogenic enzymes.
Cattle
Steroid 21-Hydroxylase
An adrenal microsomal cytochrome P450 enzyme that catalyzes the 21-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP21 gene, converts progesterones to precursors of adrenal steroid hormones (CORTICOSTERONE; HYDROCORTISONE). Defects in CYP21 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).
Cushing Syndrome
A condition caused by prolonged exposure to excess levels of cortisol (HYDROCORTISONE) or other GLUCOCORTICOIDS from endogenous or exogenous sources. It is characterized by upper body OBESITY; OSTEOPOROSIS; HYPERTENSION; DIABETES MELLITUS; HIRSUTISM; AMENORRHEA; and excess body fluid. Endogenous Cushing syndrome or spontaneous hypercortisolism is divided into two groups, those due to an excess of ADRENOCORTICOTROPIN and those that are ACTH-independent.
Adrenocortical Hyperfunction
Excess production of ADRENAL CORTEX HORMONES such as ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and/or ANDROSTENEDIONE. Hyperadrenal syndromes include CUSHING SYNDROME; HYPERALDOSTERONISM; and VIRILISM.
Addison Disease
An adrenal disease characterized by the progressive destruction of the ADRENAL CORTEX, resulting in insufficient production of ALDOSTERONE and HYDROCORTISONE. Clinical symptoms include ANOREXIA; NAUSEA; WEIGHT LOSS; MUSCLE WEAKNESS; and HYPERPIGMENTATION of the SKIN due to increase in circulating levels of ACTH precursor hormone which stimulates MELANOCYTES.
Steroid 17-alpha-Hydroxylase
A microsomal cytochrome P450 enzyme that catalyzes the 17-alpha-hydroxylation of progesterone or pregnenolone and subsequent cleavage of the residual two carbons at C17 in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP17 gene, generates precursors for glucocorticoid, androgen, and estrogen synthesis. Defects in CYP17 gene cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL) and abnormal sexual differentiation.
Entorhinal Cortex
Cerebral cortex region on the medial aspect of the PARAHIPPOCAMPAL GYRUS, immediately caudal to the OLFACTORY CORTEX of the uncus. The entorhinal cortex is the origin of the major neural fiber system afferent to the HIPPOCAMPAL FORMATION, the so-called PERFORANT PATHWAY.
Adosterol
Pregnenolone
A 21-carbon steroid, derived from CHOLESTEROL and found in steroid hormone-producing tissues. Pregnenolone is the precursor to GONADAL STEROID HORMONES and the adrenal CORTICOSTEROIDS.
Kidney Cortex
Ferredoxin-NADP Reductase
An enzyme that catalyzes the oxidation and reduction of FERREDOXIN or ADRENODOXIN in the presence of NADP. EC 1.18.1.2 was formerly listed as EC 1.6.7.1 and EC 1.6.99.4.
17-Hydroxycorticosteroids
Brain Mapping
Hyperaldosteronism
A condition caused by the overproduction of ALDOSTERONE. It is characterized by sodium retention and potassium excretion with resultant HYPERTENSION and HYPOKALEMIA.
Pituitary-Adrenal System
The interactions between the anterior pituitary and adrenal glands, in which corticotropin (ACTH) stimulates the adrenal cortex and adrenal cortical hormones suppress the production of corticotropin by the anterior pituitary.
Steroids
A group of polycyclic compounds closely related biochemically to TERPENES. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (STEROLS), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. (From Hawley's Condensed Chemical Dictionary, 11th ed)
Chromaffin Cells
Cells that store epinephrine secretory vesicles. During times of stress, the nervous system signals the vesicles to secrete their hormonal content. Their name derives from their ability to stain a brownish color with chromic salts. Characteristically, they are located in the adrenal medulla and paraganglia (PARAGANGLIA, CHROMAFFIN) of the sympathetic nervous system.
Dehydroepiandrosterone
A major C19 steroid produced by the ADRENAL CORTEX. It is also produced in small quantities in the TESTIS and the OVARY. Dehydroepiandrosterone (DHEA) can be converted to TESTOSTERONE; ANDROSTENEDIONE; ESTRADIOL; and ESTRONE. Most of DHEA is sulfated (DEHYDROEPIANDROSTERONE SULFATE) before secretion.
Receptor, Melanocortin, Type 2
A melanocortin receptor subtype found primarily in the ADRENAL CORTEX. It shows specificity for ADRENOCORTICOTROPIC HORMONE.
Cerebellar Cortex
Pheochromocytoma
A usually benign, well-encapsulated, lobular, vascular tumor of chromaffin tissue of the ADRENAL MEDULLA or sympathetic paraganglia. The cardinal symptom, reflecting the increased secretion of EPINEPHRINE and NOREPINEPHRINE, is HYPERTENSION, which may be persistent or intermittent. During severe attacks, there may be HEADACHE; SWEATING, palpitation, apprehension, TREMOR; PALLOR or FLUSHING of the face, NAUSEA and VOMITING, pain in the CHEST and ABDOMEN, and paresthesias of the extremities. The incidence of malignancy is as low as 5% but the pathologic distinction between benign and malignant pheochromocytomas is not clear. (Dorland, 27th ed; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1298)
Magnetic Resonance Imaging
Hypothalamo-Hypophyseal System
A collection of NEURONS, tracts of NERVE FIBERS, endocrine tissue, and blood vessels in the HYPOTHALAMUS and the PITUITARY GLAND. This hypothalamo-hypophyseal portal circulation provides the mechanism for hypothalamic neuroendocrine (HYPOTHALAMIC HORMONES) regulation of pituitary function and the release of various PITUITARY HORMONES into the systemic circulation to maintain HOMEOSTASIS.
Hypophysectomy
Surgical removal or destruction of the hypophysis, or pituitary gland. (Dorland, 28th ed)
RNA, Messenger
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
Mitochondria
Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)
Adrenarche
A stage of development at which the ADRENAL GLANDS undergo maturation leading to the capability of producing increasing amounts of adrenal androgens, DEHYDROEPIANDROSTERONE and ANDROSTENEDIONE. Adrenarche usually begins at about 7 or 8 years of age before the signs of PUBERTY and continues throughout puberty.
Progesterone Reductase
An enzyme that catalyzes the reduction of a 3 beta-hydroxy-delta(5)-steroid to 3-oxo-delta(4)-steroid in the presence of NAD. It converts pregnenolone to progesterone and dehydroepiandrosterone to androstenedione. EC 1.1.1.145.
Rats, Sprague-Dawley
Dehydroepiandrosterone Sulfate
Brain
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
Neurons
Glucocorticoids
A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.
Metyrapone
An inhibitor of the enzyme STEROID 11-BETA-MONOOXYGENASE. It is used as a test of the feedback hypothalamic-pituitary mechanism in the diagnosis of CUSHING SYNDROME.
Rats, Inbred Strains
Immunohistochemistry
Steroid Hydroxylases
Cytochrome P-450 Enzyme System
A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.
Frontal Lobe
Rats, Wistar
Photic Stimulation
Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.
Angiotensin II
An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the C-terminal by ANGIOTENSIN CONVERTING ENZYME. The amino acid in position 5 varies in different species. To block VASOCONSTRICTION and HYPERTENSION effect of angiotensin II, patients are often treated with ACE INHIBITORS or with ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKERS.
Organ Specificity
Fetus
Mineralocorticoids
A group of CORTICOSTEROIDS primarily associated with water and electrolyte balance. This is accomplished through the effect on ION TRANSPORT in renal tubules, resulting in retention of sodium and loss of potassium. Mineralocorticoid secretion is itself regulated by PLASMA VOLUME, serum potassium, and ANGIOTENSIN II.
Chromaffin System
Microscopy, Electron
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
Tissue Distribution
Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.
Functional Laterality
Parietal Lobe
Gyrus Cinguli
One of the convolutions on the medial surface of the CEREBRAL HEMISPHERES. It surrounds the rostral part of the brain and CORPUS CALLOSUM and forms part of the LIMBIC SYSTEM.
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Fushi Tarazu Transcription Factors
Stress, Physiological
Autoradiography
Histocytochemistry
Hyperplasia
Cyclic AMP
An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.
In Situ Hybridization
Endocrine Glands
Pituitary Gland
Hyperandrogenism
A condition caused by the excessive secretion of ANDROGENS from the ADRENAL CORTEX; the OVARIES; or the TESTES. The clinical significance in males is negligible. In women, the common manifestations are HIRSUTISM and VIRILISM as seen in patients with POLYCYSTIC OVARY SYNDROME and ADRENOCORTICAL HYPERFUNCTION.
Base Sequence
Restraint, Physical
Image Processing, Computer-Assisted
Cyanoketone
Ovary
The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.
Chromaffin Granules
Organelles in CHROMAFFIN CELLS located in the adrenal glands and various other organs. These granules are the site of the synthesis, storage, metabolism, and secretion of EPINEPHRINE and NOREPINEPHRINE.
Psychomotor Performance
Cats
The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)
Renin
Nerve Net
A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.
Bucladesine
A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)
Vibrissae
Hormones
Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.
Temporal Lobe
Cells, Cultured
Microsomes
Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
Adrenal Rest Tumor
Neoplasm derived from displaced cells (rest cells) of the primordial ADRENAL GLANDS, generally in patients with CONGENITAL ADRENAL HYPERPLASIA. Adrenal rest tumors have been identified in TESTES; LIVER; and other tissues. They are dependent on ADRENOCORTICOTROPIN for growth and adrenal steroid secretion.
Androgens
Compounds that interact with ANDROGEN RECEPTORS in target tissues to bring about the effects similar to those of TESTOSTERONE. Depending on the target tissues, androgenic effects can be on SEX DIFFERENTIATION; male reproductive organs, SPERMATOGENESIS; secondary male SEX CHARACTERISTICS; LIBIDO; development of muscle mass, strength, and power.
Stimulation, Chemical
The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.
Freeze Etching
A replica technique in which cells are frozen to a very low temperature and cracked with a knife blade to expose the interior surfaces of the cells or cell membranes. The cracked cell surfaces are then freeze-dried to expose their constituents. The surfaces are now ready for shadowing to be viewed using an electron microscope. This method differs from freeze-fracturing in that no cryoprotectant is used and, thus, allows for the sublimation of water during the freeze-drying process to etch the surfaces.