Ventricle of the brain

In mammals, ciliated cells line the respiratory air passages, the fallopian tubes, and the ventricles of the brain. The cilia beat in a coordinated manner in waves that propel fluids, suspended cells, and small particles along a surface. The motility of the sperm cell is provided by a single flagellum. 

Chemoreceptor trigger zone Located in the area postrema of the fourth ventricle of the brain, it is exposed to cerebrospinal fluid and blood and is easily stimulated by circulating toxins to induce nausea and vomiting. 

Large doses of sodium fluoroacetate injected intravenously into the lateral ventricles of the brain of cats produced increases in the electrical activity of the thalamus and hypothalamus.3 Rises in blood glucose to 400 mg./lOO ml. have been reported. 

Now let us go back to methyldopa. The afore-mentioned experiments by HENNING and van ZWIETEN (21) indicated a central mode of action. HEISE and KRONEBERG (22), perfusing part of the third and the entire fourth ventricle of the brain in cats with methyldopa, a-me-thyldopamine and a-methylnoradrenaline were able to show a decrease in blood pressure. These effects were significantly blocked by pretreatment with yohimbine and to a lesser extent by phentolamine. These experiments support the concept of blood pressure lowering by an action on central a-adrenoreceptors. 

The choroid plexus in the ventricles of the brain produce CSF at a constant rate of 500ml.day 1 or 0.35ml.min 1. The total volume of CSF is around 150 ml in the average adult. The rate of reabsorption of CSF is proportional to its outflow pressure. 

Visceral variations and anomalies occur in minipigs. In males the most frequent flnding is malpositioned testes which are seen in 12% of the males. Dilatation of the ventricles of the brain is seen approximately in 5% of all fetuses (12). 

The Foot Tap test was developed as an indication of CNS activity, in that a compound must penetrate the CNS to be active. In the test, a peptidic NK] receptor agonist, GR-73632 is administered by i.c.v. injection through a hole in the skull into the ventricles of the brain to induce the foot-tapping behavior. Once again, aprepitant (1) proved to have the longest duration of action by virtue of its lowest ID50 value at 24 h postdose, as shown in Table 4.8... 

We have, therefore, as a first step, prepared brain DNA of varying degrees of purity. This DNA was injected into the ventricles of the brain of other animals of the same species. In one hour, protein synthesis was found to increase significantly. Biochemical analyses showed that the DNA had been incorporated in the recipient s brain cells in a polymerized state. . . (H. Hyden, in Koestler and Smythies 1969, p. 102)... 

CSF cerebrospinal fluids are fluid in the ventricles of the brain, between the arachnoid and pia mater, and surrounding the spinal cord that absorbs shocks and maintains uniform pressure. 

There are other aspects of barrier function that also change with development. The tanycytic barrier between the median eminence and the arcuate nucleus develops after birth in the rodent (Peruzzo et al 2000). This means the arcuate nucleus is very vulnerable to circulating neurotoxins during the neonatal period. For example, monosodium glutamate destroys the arcuate nucleus with resulting obesity when given intravenously to a neonate, but not an adult. The epithelial cells, which line the ventricles of the brain, have tight junctions even over non-CVO sites in neonates, but not adults. Thus, neonates have a CSF-brain barrier, which limits the diffusion of substances between brain tissue and CSF... 

Neuroglia include (1) ependymal cells lining the ventricles of the brain and the central canal of the spinal cord, (2) cells of the PNS (Schwann cell) and CNS (oligodendrocyte) that wrap around axons to form compacted plasma membranes (myelin) that provide electrical insulation to speed nerve conduction, (3) cells (astrocytes) that interface between nerve cells and capillaries in the CNS, regulate interstitial water content, concentration, remove and metabolize certain NT molecules, and proliferate following injury. 

CSF is secreted by the choroid plexuses, around the cerebral vessels, and along the walls of the ventricles of the brain. It fills the ventricles and cisternae, bathes the spinal cord, and is reabsorbed into the blood through the arachnoid villi. CSF turnover is rapid, exchanging totally about four times per day. More than 80% of CSF protein content originates from plasma by ultrafiltration and pinocytosis the remainder is from intrathecal synthesis. The lowest concentration of total protein and the smallest proportion of the larger protein molecules are in the ventricular fluid as the CSF passes down to the lumbar spine (from which site specimens are usually collected), the protein concentration increases. This difference in concentration at different levels of the CNS is illustrated by the following reference intervalsd ... 

Endorphin is a 31-amino-acid polypeptide released together with ACTH. When introduced into the third ventricle of the brain, it produces dramatic behavioral changes, but when injected systemically, it does not. Thus, the function of circulating 3-endorphin remains unclear. The CNS and gastrointestinal effects of the hormone are probably produced by that secreted locally. Circulating 8-endorphin may act in conjunction with enkephalins released by the adrenal medulla to produce stress analgesia. 

The CTZ, located in the area postrema of the fourth ventricle of the brain, is a major chemosensory organ for emesis and is usually associated with chemically induced vomiting. Because of its location, blood-borne and cerebrospinal fluid toxins have easy access to the CTZ. Therefore cytotoxic agents stimnlate primarily this area rather than the cerebral cortex and visceral afferents. Similarly, pregnancy-associated vomiting probably occurs through stimulation of the CTZ. 

Macroglial cells are of ectodermal origin and include the astrocytes, ependymal cells, oligodendrocytes, and Schwann cells. Astrocytes appear to be primarily supportive in function and under microscopic examination can be seen to envelope axons and dendrites and buttress against the adventitial layer of blood vessels. In the gray matter of brain, which is composed primarily of perikarya, they have a clear protoplasmic appearance, whereas in the white matter, which is composed primarily of neuronal processes, they appear fibrous. Ependymal cells line the ventricles of the brain, are ciliated. 

Figure 1. A silicone elastomer hydrocephalus shunt. This type of shunt is used to drain cerebrospinal fluid from the ventricle of the brain to either the vascular system or to the peritoneal cavity. The first hydrocephalus shunt was developed by Hoi ter in 1955. The shunt in this illustration contains a dual flushing chamber to assure continual function of the shunt, and is designed to drain cerebral spinal fluid from the ventricle of the brain to the peritoneal cavity.

Alzheimer s disease is primarily the result of degeneration or death of nerve cells in the cerebral cortex and in areas that usually control functions such as memory, personality, logical thinking, and other. As the nerve cells become withered and small, they cause the enlargement of the ventricles of the brain. Recent events are not remembered, the individual is not able to perform calculations or make plans and decisions. Abrupt personality changes alarm family members and friends thus disabling the person from functioning normally. 

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