Membranes sentence example
These vascular membranes are called the lateral septa.
The majority of birds possess a pair of internal tympaniform membranes forming the inner or median walls of the bronchi, which are there furnished with semi-rings only.
External tympaniform membranes exist, with great variations, between the specialized one or two last tracheal and some of the first bronchial rings.
Inner and outer membranes may exist on the bronchi.
Elastin occurs either as thick strands or as membranes; it constitutes the " elastic tissue " of the anatomist.Advertisement
This section comprehends three species only, known as Phalaropes or swimming sandpipers, which are distinguished by the membranes that fringe their toes, in two of the species forming marginal lobes,' and by the character of their lower plumage, which is as close as that of a duck.
Experiments with membranes of copper ferrocyanide have verified this result for solutions of cane-sugar of moderate dilutions.
Although even good membranes of copper ferrocyanide are rarely perfectly semi-permeable, and in other membranes such as indiarubber, &c., which have been used, the defects from the theoretical values of the equilibrium pressure are very great, yet, in the light of the exact verification of theory given by the experiments described above, it is evident that such failures to reach the limiting value in no wise invalidate the theory of osmotic equilibrium.
The conceptions of osmotic pressure and ideal semi-permeable membranes enable us to deduce other thermodynamic relations between the different properties of solutions.
The passage of dissolved substances through animal and vegetable membranes was the subject of many early experiments.Advertisement
It was found that substances like mineral salts, which crystallize well from solution, passed such membranes with comparative ease, while the jelly-like substances such as albumen passed with extreme slowness if at all.
As in other cell-walls, so here the older membranes may be altered by deposits of various substances, such as resin, calcium oxalate, colouring matters; or more profoundly altered throughout, or in definite layers, by lignification, suberization (Trametes, Daedalea), or swelling to a gelatinous mucilage (Tremella, Gymnosporangium), while cutinization of the outer layers is common.
P. Pfeffer (Osmotische Untersuchungen, Leipzig, 1877) was the first to obtain satisfactory measurements of osmotic pressures of cane-sugar solutions up to nearly I atmosphere by means of semi-permeable membranes of copper ferrocyanide.
The serous membranes show petechiae and haemorrhages.
The substance of the brain, spinal cord and nervetrunks is normal, but the membranes are engorged.Advertisement
The most important applications of the theory of vibrations are to the case of continuous systems such as strings, bars, membranes, plates, columns of air, where the number of degrees of freedom is infinite.
They pass more readily through mucous membranes, but almost every one of these is provided not only with a coating of mucus, which obstructs their passage, but with some reflex mechanism which tends to remove them.
For the purpose of checking the inflammatory processes and lessening discharge from mucous membranes astringents are employed.
They are also employed locally as sprays and douches to the nose, throat, vagina and rectum, for catarrhal conditions of the mucous membranes.
When the swollen wall is dense and regular in appearance the term " capsule " is applied to the sheath as in Leuconostoc. Secreted pigments (red, yellow, green and blue) are sometimes deposited in the wall, and some of the iron-bacteria have deposits of oxide of iron in the membranes.Advertisement
They dissolve in water to form solutions, which do not penetrate parchment membranes, hence the name colloidal.
The treatment consists in the use of solutions of common salt, followed by copious draughts of milk or white of egg and water or soap in water, in order to dilute the poison and protect the mucous membranes of the oesophagus and stomach from its action.
Subjection to the temperature of boiling water for, say, half an hour seemed an efficient mode of sterilization, until it was discovered that the spores of bacteria are so involved in heat-resisting membranes, that only prolonged exposure to dry, baking heat can be recognized as an efficient process of sterilization.
Formerly the animal oils and fats were obtained by heating the tissues containing the oils or fats over a free fire, when the cell membranes burst and the liquid fat flowed out.
The action of tannic acid is strictly local, and depends upon its power of precipitating albumen and of destroying germs. It thus acts as an astringent on all mucous membranes.Advertisement
They are readily absorbed into the blood, and they are excreted chiefly by the kidneys in a more or less altered form, and probably also by the different mucous membranes, and even by the skin.
How are such small amounts of vitamin E able to protect cell membranes against sustained free radical attack?
Quercetin possesses powerful antioxidant properties and like other bioflavonoids, has the ability to stabilize cell membranes.
Toxic substances may disturb normal cell function, damage cell membranes, interfere with enzyme and immune systems and RNA and DNA activity.
This means that contractions are started with an unfavorable cervix, often with the membranes still intact.Advertisement
Envelope membranes from spinach chloroplasts are a site of metabolism of fatty acid hydroperoxides.
Type v collagen has also been found in the basement membranes of muscle fibers, except at the point where muscle fibers are innervated.
Regenerated cellulose was the original industry standard but Professor Courtney started his research career by developing synthetic membranes based on vinyl copolymers.
These membranes are called the meninges, the outermost membrane is called the dura mater, then the arachnoid and then the pia mater.
Control is exerted within a network of membranes called endoplasmic reticulum (ER ), which transports proteins throughout the cell.Advertisement
A purulent exudate extends along the meningeal membranes, accompanied by hemorrhage and thrombosis.
For example, precursors of SREBP (sterol response element binding protein) transcription factors are integral proteins embedded in endoplasmic reticulum membranes.
Keep Moist There are solutions or ointments that you can use in-flight to keep your nasal membranes moist.
It appears, however, to be associated with a leucine transporter system across neuronal cell membranes and may increase intracellular GABA.
Landfills are lined with clay and flexible synthetic membranes intended to prevent leachate escaping and contaminating the groundwater.Advertisement
Each capsule is prepared in a base of essential fatty acids, including lecithin, the major component of cell membranes.
Other triggers cab be changes in host defenses e.g. friction during sexual intercourse inflaming the mucous membranes.
The ear flaps, the tympanic membranes, are the two large ' scales ' just behind the jaw-bone.
An allergic reaction occurs in the mucus membranes that line the inside of its nasal passages.
It reacts by immunoblotting with a component of 30 - 35 kDa in reduced or non - reduced erythrocyte membranes.Advertisement
In order for a cell to use calcium as a signaling molecule, the cell must create calcium gradients across membranes.
The disorder can affect the mucous membranes of the mouth and genitals where it looks like a grayish erosion (shallow ulcer ).
Synthetic membranes are best covered with a loose mulch.
Calcium also helps conduct nerve impulses, regulate your heartbeat, and maintain cell membranes.
Physiological Properties of TTX TTX is an especially potent neurotoxin, specifically blocking voltage-gated sodium channels on the surface of nerve membranes.Advertisement
This consists of inner and outer nuclear membranes traversed by the nuclear pores.
Antioxidants inhibit the oxidation of lipids in cell membranes, leading to impairment of cell function.
Reverse osmosis a high pressure filtration system that uses selectively permeable membranes with extremely small pores to separate ions and particles.
Ion channels pores in cell membranes that allow charged ions into and out of the cell.
Endoplasmic reticulum - a system of inner cell membranes which is continuous with the nuclear membrane.
Expectant management of women with prelabour rupture of the membranes at term should not exceed 96 hours following membrane rupture.
Clinical antecedents linked with this type of injury include maternal pyrexia, prolonged preterm rupture of membranes and maternal leucocytosis.
In babies and small children scurvy also causes bleeding under the bone membranes, causing very tender swellings so that infants resent being touched.
There has been some literature claiming that hypertonic saline is of value when the membranes of the nose are extremely swollen.
Density of newly synthesized plasma membrane proteins in intracellular membranes.
The dimeric PSII supercomplex used for this study was isolated from spinach chloroplast thylakoid membranes.
Rapid absorption, such as from a very vascular site ie mucous membranes.
These membranes are durably waterproof, highly breathable, long lasting and extremely cold and crease resistant.
The superior surface is in contact with the diaphragm, but has peritoneum between (see Coelom And Serous Membranes).
Collemaceae); in these the algae are Chroococcaceae and Nostocaceae, and the fungus makes its way into the gelatinous membranes of the algal cells and ramifies there (fig.
Even when they have passed through an abrasion in the skin or through the mucous membranes and enter the blood they are met, in some instances, by a toxic action of the blood itself upon them; and in others they are attacked by the white corpuscles, which destroy them, eat them up, and digest them, the process being known as phagocytosis.
However, all women are not at equal risk from having prolonged rupture of membranes.
By 26 weeks, almost 43 per cent had ruptured membranes compared with 24 per cent of controls.
The opening/closing of channels with different ion selectivities give rise to changes in voltage across cell membranes.
Has potent antioxidant effects which are important in stabilizing cell membranes in the body.
The space between the two outer membranes is called the subdural space.
Gently wiggle it so the oil coats the membranes on all sides.
When inhaled into nasal passages and further into the lungs, it can theoretically become stuck to mucus membranes and cause breathing problems.
It stimulates the mucous membranes to drain and thins out the mucous that is being formed.
If you consider that the action may be on the mucous membranes themselves and not necessarily on the invading bacteria, you'll understand why you should wait to take goldenseal until your running nose blossoms.
Adding a wet room is a bit expensive and the help of a professional is advisable, since you'll need waterproof membranes and a special draining system.
Designed for external application only, avoid getting DHA onto your lips, eyes or mucus membranes for safety.
With its intricate curves and bends and delicate skin (not to mention the sensitive mucous membranes you need to watch out for!), the eye area is deserving of the extra attention.
Novelty contact lenses are thin membranes of plastic placed on the cornea of the eye to improve eye function or, in some cases, just to change how the eye looks.
To keep the lenses moisturized and comfortable, Proclear uses a substance found in human cell membranes called phosphorylcholine.
I'm assuming a thicker one or one with membranes in it would be better, but I can't seem to find one.
Subarachnoid hemorrhage-A collection of blood in the subarachnoid space, the space between the arachnoid and pia mater membranes that surround the brain.
Symptoms of plant poisoning range from irritation of the skin or mucous membranes of the mouth and throat to nausea, vomiting, convulsions, irregular heartbeat, and even death.
Osteoarthritis-A noninflammatory type of arthritis, usually occurring in older people, characterized by degeneration of cartilage, enlargement of the margins of the bones, and changes in the membranes in the joints.
Kawasaki syndrome-A syndrome of unknown origin that affects the skin, mucous membranes, and the immune system of infants and young children.
Meningitis-An infection or inflammation of the membranes that cover the brain and spinal cord.
This congestion results when membranes lining the nose become swollen.
This narrowing reduces the blood supply to the swollen membranes, causing them to shrink.
Subarachnoid-Referring to the space underneath the arachnoid membrane, the middle of the three membranes that sheath the spinal cord and brain.
Candidiasis can affect the skin, nails, and mucous membranes throughout the body including the mouth (thrush), esophagus, vagina (yeast infection), intestines, and lungs.
Sore throat is a painful inflammation of the mucous membranes lining the pharynx.
Trachoma, also called granular conjunctivitis or Egyptian ophthalmia, is a contagious, chronic inflammation of the mucous membranes of the eyes, caused by the bacterium Chlamydia trachomatis.
Subdural hematoma-A localized accumulation of blood, sometimes mixed with spinal fluid, in the space between the middle (arachnoid) and outer (dura mater) membranes covering the brain.
Lipids are stored in the body as energy reserves and are also important components of cell membranes.
It is comprised of three layers and the membranes that separate these layers.
Herpes simplex virus is transmitted by infected body fluids (such as saliva) when they contact breaks in another person's skin or mucous membranes.
The symptoms of FMF are due to inflammation of one or more of the serosal membranes (serositis).
In addition to PPIs, the doctor may prescribe coating agents, such as sucralfate (Carafe), to cover the sores and mucous membranes of the esophagus and stomach.
The body requires some, called essential fatty acids, to form membranes and synthesize important compounds.
Decongestants-A group of medications, such as pseudoephedrine, phenylephrine, and phenylpropanolamine, that shrink blood vessels and consequently mucus membranes.
Causes include non-functioning kidneys and premature rupture of membranes.
Mucus-The thick fluid produced by the mucous membranes that line many body cavities and structures.
Injury to the mucous membranes of the mouth and gums leaves places where bacteria can grow.
They involve mutations in the proteins that transport copper, that is, in special channels that allow the passage of copper ions through cell membranes.
Fractures may also damage the membranes that line the nasal passages, leading to possible formation of scar tissue, obstruction of the airway, and damage to the child's sense of smell.
Another common cause of injury to the nasal passages in children is scratching or picking the inside of the nose, often as a reaction to dry and itching nasal membranes during the heating season in colder climates.
An increasingly common form of chemical injury to the nasal membranes in toddlers is alkali burns caused by leakage from small batteries placed in the nose.
Use a humidifier during heating season to prevent drying and itching of the nasal membranes and coat the inside of the child's nose with petroleum jelly.
Meningitis is a serious inflammation of the meninges, the membranes (lining) that surround the brain and spinal cord.
Bruises, or ecchymoses, are a discoloration and tenderness of the skin or mucous membranes due to the leakage of blood from an injured blood vessel into the tissues.
Herpes simplex virus-A virus that can cause fever and blistering on the skin and mucous membranes.
They can infect various parts of the body, especially the skin and mucous membranes.
A compartment syndrome is a potentially debilitating condition in which the muscles of the lower leg grow too large to be contained within membranes that enclose them.
Symptoms include sudden onset of small bruises or spots of hemorrhage on the skin or bleeding into mucous membranes (such as nosebleeds).
This is an invasive procedure that requires the rupture of membranes (amniotomy) and is associated with occasional complications.
Cranberry juice has the ability to keep bacteria from adhering to the membranes and can help prevent infection whenever there is increased risk.
Common sites include the lungs, spleen, liver, mucous membranes, skin, and lymph nodes.
In rhinitis, the mucous membranes become infected or irritated, producing a discharge, congestion, and swelling of the tissues.
Research supported by the U.S. Public Health Service during the 1990s found that an inadequate diet during pregnancy was associated with premature rupture of amniotic sac membranes and premature birth.
Streptococcal sore throat, or strep throat, as it is more commonly called, is a bacterial infection of the mucous membranes lining the throat or pharynx.
These complexes can be deposited in blood vessels and on membranes, causing inflammatory reactions that may be either localized or throughout the body.
Angioedema-Patches of circumscribed swelling involving the skin and its subcutaneous layers, the mucous membranes, and sometimes the organs frequently caused by an allergic reaction to drugs or food.
Kawasaki syndrome is a potentially fatal inflammatory disease that affects several organ systems in the body, including the heart, circulatory system, mucous membranes, skin, and immune system.
The palms, soles, and mucous membranes that line the eyelids and cover the exposed portion of the eyeball (conjuntivae) become purplish-red and swollen.
Others develop pneumonia, diarrhea, dry or cracked lips, jaundice, or an inflammation of the membranes covering the brain and spinal cord (meningitis).
The name comes from the key symptoms of the disease, which involve the mucous membranes of the mouth and throat, the skin, and the lymph nodes.
In some cases, the skin, mucous membranes, and nails of a person with CO poisoning are cherry red or bright pink.
Often refers to one of the air-filled cavities surrounding the eyes and nose that are lined with mucus-producing membranes.
During pregnancy, the fetus excretes AFP in urine, and some of the protein crosses the fetal membranes to enter the mother's blood.
Bacteria may be carried from the middle ear or the membranes that cover the brain.
Transmission of many perinatal infections occurs during childbirth, particularly in cases when invasive techniques such as episiotomy or artificial rupture of membranes are employed.
This infection can cause premature rupture of the membranes and early labor.
More serious damage can be caused by hard or sharp objects that penetrate the surface of the eye and become embedded in the cornea or conjunctivae (the mucous membranes lining the inner surface of the eyelids).
Following an animal bite or contact between a child's mucous membranes and an animal's saliva, an attempt is usually made to determine whether the animal has rabies.
Hand washing is one of the biggest factors in the transmission of all diseases, and it is especially true of herpes simplex since it is spread by respiratory droplets through mucosal membranes.
Meningoencephalitis-Inflammation of the brain and its membranes; also called cerebromeningitis or encephalomeningitis.
Both diseases involve mutations in copper transport proteins, special channels that allow copper ions to pass through cell membranes.
The skin, bones, and mucous membranes are all affected by bejel.
The skin turns pale and cold, the mucous membranes lining the mouth and nose lose their natural moisture.
Dura mater-The strongest and outermost of three membranes that protect the brain, spinal cord, and nerves of the cauda equina.
The symptoms are like measles but are not nearly as severe, and spots never appear on the mucous membranes of the mouth.
There are potential complications from an amniocentesis, i.e., preterm labor, spontaneous rupture of membranes, fetal or placental injury; and the clinician performing the procedure should explain what these are prior to the procedure.
These pediculicides should not be used on children under two; near broken skin, eyes, or mucous membranes; in the bathtub or shower; by those with allergies, asthma, epilepsy, or certain other medical conditions.
Layers of tissue called hyaline membranes keep the oxygen that is breathed in from passing into the blood.
If the membranes have ruptured, surfactant can easily be measured in a sample of vaginal fluid.
Like the brain, the spinal cord is enclosed in three membranes (meninges).
Acute otitis media often occurs as an aftereffect of upper respiratory infections, in which the eustachian tube and nasal membranes become swollen and congested.
People with respiratory allergies, hay fever, and sinus infections have swollen nasal membranes that are fragile and more likely to bleed.
Changes from cold to warm air or dry to humid air stress the delicate membranes of the nose and make it vulnerable to injury and bleeding.
The object can tear the delicate membranes of the nose.
Botanical medicine can help to maintain open airways and heal damaged mucous membranes.
When absorbed into the bloodstream, they may cause hives (urticaria) or more severe reactions involving recurrent, non-inflammatory swelling of the skin, mucous membranes, organs, and brain (angioedema).
Decongestants dry up nasal passage tissues and reduce swollen nasal membranes so as to relieve congestion.
Allergic rhinitis-Swelling and inflammation of the nasal membranes caused by sensitivity to airborne matter like pollen or cat hair.
Your membranes rupture and contractions don't begin within a set amount of time, usually around 6-12 hours.
In an amniotomy your care provider will artificially rupture your membranes.
Many facilities require you to deliver within 12 to 24 hours after membranes are ruptured.
How long will your doctor let you labor with your membranes ruptured?
The membranes which surround the baby and hold in the amniotic fluid will rupture, releasing a trickle or a gush of fluid.
Your baby's heart rate can be affected by the contractions, his/her movements, and interventions such as narcotics, an epidural, or an amniotomy (rupturing your membranes).
In addition, your membranes must be ruptured to place the monitor.
If your membranes are ruptured, most care providers require you to deliver within 12-36 hours.
Vitamin E - maintains integrity of cell membranes throughout the body and protects fats in low density lipoproteins from oxidation.
Stripping the membranes is also a method doctors and hospitals may use to start labor, however, this method should never be used as a self induction technique.
Inserting anything into the vaginal canal can be very dangerous in late pregnancy and create risk of infection and other complications, so do not attempt to strip your membranes on your own.
Another visible sign is the burst of water that is released when membranes surrounding the baby rupture, allowing clear fluid to trickle or rush out.
This shell develops into membranes that protect and nourish the inner cells.
These contractions are usually what will eventually break the membranes (water breaking), at which point the actual birth should take place within 24 hours in order to prevent infections and complications for the baby.
Other methods that a doctor may perform such as stripping the membranes or using the drug pitocin can also be effective in kick starting labor, but these are not always an option.
This process puts strain on your cell membranes, and has the power to damage or even kill cells.
Adequate vitamin A in the diet promotes healthy skin and hair, and also increases your immunity, helps vision, encourages bone and tooth development, and maintains healthy mucous membranes.
Vitamin A, or retinol, is a very important nutrient for your eyes, skin and mucous membranes.
Referred to as oxidation, rancid fish oils lead to lipid peroxides, which "can (and do) start free radical cascades that can damage fatty cellular membranes," according to Dr. Eades.
It binds to the intestines' mucous membranes and helps to maintain the proper balance of good bacteria in your digestive system.
Omega-3 fats play a crucial role in the structure of cell membranes and are critical for vision.
Essential fatty acids help build cell membranes and reduce inflammation.
This is very important for your muscle cells because the growth ad recuperation of muscles cells depends on strong cell membranes.
Even conventional medicine has adopted this age-old concept of bringing healing to the sick via feeding the mucous membranes in the epidermis, in the respiratory track, in the digestive track and in the genitourinary system.
Sharing cups, eating utensils, straws, snacks, and any other items that have been near the mouth or other mucous membranes can be a speedy route to the illness highway.
Cholesterol is a type of fat that is very important to all the body's cell membranes' functionality.
Equally common on teenagers and adults, warts are actually benign skin tumors representing several different types of thickened mucous membranes.
This topical ointment disrupts the fungus activity by breaking down its cell membranes.
A good example may be made with two cylindrical tin cups; the bottoms form the membranes and the cups the mouthpieces.
When the connecting string is held taut and sounds, such as those of ordinary speech, are produced in front of one of the membranes, pulses corresponding to the fluctuations of the atmospheric pressure are transmitted along the string and communicated to the other membrane, which in its turn communicates them to the air, thus reproducing the sound.
Both cuticularized and suberized membranes are insoluble in cuprammonia, and are colored yellow or brown in a soltition of chlor-iodide of zinc. It is probable that the corky or suberized cells do not contain any cellulose (Gilson, Wisselingh); whilst cuticularized cells are only modified in their outer layers, cellulose inner layers being still recognizable.
The suberized and cuticularized cell-walls appear to contain a fatty body called suberin, and such cell-walls can be stained red by a solution of alcanin, the lignified and cellulose membranes remaining unstained.
They are very thin-walled membranes, very poor in blood-vessels, formed by the bulged-out pleural or peritoneal covering of the lungs, through the parabronchial tubes of which they are filled with air.
Essential are vibrating membranes between the cartilaginous framework, and next, special muscles for regulating the tension.
The essential feature is that the proximal end of the inner membranes is attached to the last pair of tracheal rings; outer tympaniform membranes exist generally between the 2nd, 3rd and 4th bronchial semi-rings.
The outer membranes are spread out between two or more successive bronchial semi-rings, a distance from the trachea which is, in typical cases, devoid of sounding membranes; some Cuculi, Caprimulgi, and some owls.
The lower portion of the trachea consists of thin membranes, about half a dozen of the rings being very thin or deficient.
Heider bryonic membranes are vestigial or entirely wanting.
Graber, however (1889), of the embryonic membranes has lately been shown by Heymons.
In moths and certain saw-flies there is no rupture of the membranes; the Russian zoologists Tichomirov and Kovalevsky have described the growth of both amnion and embryonic ectoderm around the yolk, the embryo being thus completely enclosed until hatching time by both amnion and serosa.
In the stomach it casts its membranes and becomes mobile, bores through the stomach walls and encysts usually in the bodycavity of its first and invertebrate host.
Salicylic acid is now never given internally, being replaced by its sodium salt, which is much cheaper, more soluble and less irritating to mucous membranes.
Applied externally lead salts have practically no action upon the unbroken skin, but applied to sores, ulcers or any exposed mucous membranes they coagulate the albumen in the tissues themselves and contract the small vessels.
Internally lead has an astringent action on the mucous membranes, causing a sensation of dryness; the dilute solution of the subacetate forms an effective gargle in tonsillitis.
By mucoid is understood a soft gelatinous substance containing mucin, or pseudomucin, which is normally secreted by the epithelial cells of both the mucous membranes and glands.
Certain degenerative changes in the supra-renal glands may lead to Addison's disease, which is characterized by an excessive pigmentary condition of the skin and mucous membranes.
These soluble salts combine with the albumins in the body, and are deposited as minute granules of silver albuminate in the connective tissue of the skin papillae, serous membranes, the intima of arteries and the kidney.
The terrible nervous sequels of some forms of inflammation of the membranes of the brain, again, are due primarily to microbic invasion rather of the membranes than of their nervous contents; and many other diseases may be added to this list.
And the attention of modern psychologists is now being drawn to his doctrine of the relation of the elements of the universe to the membranes of the body.
It possesses only slight influence over the heart and respiration, but it has a specific effect on mucous membranes as the elimination of the drug takes place largely through the lungs, where it aids in loosening bronchial secretions.
The relation of the vagina to the peritoneum is noticed under Coelum and Serous Membranes.
But other relations between the different properties of solutions have been investigated by another series of conceptions which we shall proceed to develop. Some botanical experiments made about 1870 suggested the idea of semi-permeable membranes, i.e.
Artificial membranes are seldom or never perfectly semi-permeable - some leakage of solute nearly always occurs, but the imperfections of actual membranes need no more prevent our use of the ideal conception than the faults of real engines invalidate the theory of ideal thermodynamics founded on the conception of a perfect, reversible, frictionless, heat engine.
Your care provider will use an amniohook, which looks like a crochet hook, to hook a small tear in your bag of membranes.
Once the membranes have been ruptured you will have the baby within 24 to 36 hours, even if it's via a cesarean.
However, if your membranes rupture, he/she may have no choice but to deliver your baby.
For many women, this is not a problem unless their membranes have ruptured.