In a recent paper, Evelyn I. Fernald 1 has shown that the osmotic concentration of the sap of different portions of stems is correlated with the tendency of buds to develop on those portions. She has found by freezing point measurements on the expressed sap that in actively growing stems of privet, chestnut, Pkiladelphus, and Bryophyllum there is a concentration gradient, the highest concentrat...

The potential distribution within the internodal axon of mammalian nerve fibers is derived by applying known node potential waveforms to the ends of an equivalent circuit model of the internode. The complete spatial/temporal profile of action potentials synthesized from the internodal profiles is used to compute the node current waveforn, and the extracellular action potential around fibers cap...

Observations with the electron microscope of longitudinal sections of the sciatic nerves of infant mice during the period of early myelin formation are described. These observations are interpreted in relation to previous studies of transverse sections, and a general picture of the formation of an internodal length of the myelin sheath in three dimensions is formulated. In general, an internoda...

Myelinating Schwann cells regulate the localization of ion channels on the surface of the axons they ensheath. This function depends on adhesion complexes that are positioned at specific membrane domains along the myelin unit. Here we show that the precise localization of internodal proteins depends on the expression of the cytoskeletal adapter protein 4.1G in Schwann cells. Deletion of 4.1G in...

Myelin, made by oligodendrocytes, is essential for rapid information transfer in the central nervous system. Oligodendrocyte precursors (OPs) receive glutamatergic synaptic input from axons but how this affects their development is unclear. Murine OPs in white matter express AMPA receptor (AMPAR) subunits GluA2, GluA3 and GluA4. We generated mice in which OPs lack both GluA2 and GluA3, or all t...

In the peripheral nerve trunks of vertebrates, the distance between the nodes of Ranvier is normally greater on fibres of larger diameter than on those of smaller size (Ranvier, 1875; Key and Retzius, 1876). At the time of myelination during development , internodal length is uniformly short, the nodes being spaced about 150 to 300 ,u apart. Each inter-node represents the territory of an indivi...

Sex expression in cucumber is influenced by hormonal and environmental factors such as day length and temperature. Increasing female flowers that will develop to fruit is a trick for increasing yield, hence it’s importance. Likewise, it would help breeders through hybridizing process. Ethylene as a plant hormone is known to increase female flowers of most members of Cucurbitaceae family but as ...

The effects of aging on myelinated nerve fibers of the central nervous system are complex. Many myelinated nerve fibers in white matter degenerate and are lost, leading to some disconnections between various parts of the central nervous system. Other myelinated nerve fibers are affected differently, because only their sheaths degenerate, leaving the axons intact. Such axons are remyelinated by ...

The myelin-associated glycoprotein (MAG) is a member of the immunoglobulin gene superfamily that is selectively expressed by myelin-forming cells. A developmentally regulated, alternative splicing of a single MAG transcript produces two MAG polypeptides (72 and 67 kD) in the central nervous system (CNS). MAG occurs predominantly as the 67-kD polypeptide in the peripheral nervous system (PNS). T...

Axons in the PNS and CNS are ensheathed by multiple layers of tightly compacted myelin membranes. A series of cytoplasmic channels connect outer and inner margins of PNS, but not CNS, myelin internodes. Membranes of these Schmidt-Lantermann (S-L) incisures contain the myelin-associated glycoprotein (MAG) but not P(0) or proteolipid protein (PLP), the structural proteins of compact PNS (P(0)) an...