We have proposed that positional information along the anteroposterior axis is specified by a signal from the polarizing region and that position may be specified by the concentration of a diffusible morphogen. While this model can account for a variety of results it is now clear that a model based on intercalation by growth of positional values can do the same. The distinction between the two ...

The presence of polarizing activity in the limb buds of developing avian embryos determines the pattern of the anteroposterior axis of the limbs in the adult. Maps of the spatial distribution and the strength of the signal within limb buds of different stages are well documented. Polarizing activity can also be found in Hensen's node in the early embryo. We have mapped the distribution of polar...

Pattern in the developing limb depends on signaling by polarizing region mesenchyme cells, which are located at the posterior margin of the bud tip. Here we address the underlying cellular mechanisms. We show in the intact bud that connexin 43 (Cx43) and Cx32 gap junctions are at higher density between distal posterior mesenchyme cells at the tip of the bud than between either distal anterior o...

An estimate of the time required for positional signalling in the chick wing bud was obtained by grafting irradiated quail polarizing regions to host wing buds and removing them at various times. Such polarizing regions must be present for at least 15 h to induce additional structures in the host wings. This results is discussed in terms of a diffusible morphogen model.

Presently different optical devices are used practically at all modern neutron sources to form neutron beams. The basic event in forming neutron optics at PNPI was creation of highly efficient polarizing mirror on the glass substrate in 1972 [1,2]. It had a polarizing Ñî 60 Fe 40 coating and an antireflective Ti 85 Gd 15 underlayer. The coatings were prepared by vacuum thermal evaporation of ma...

OBJECTIVES Potassium-based depolarizing St Thomas' Hospital cardioplegic solution No 2 administered as intermittent, oxygenated blood is considered as a gold standard for myocardial protection during cardiac surgery. However, the alternative concept of polarizing arrest may have beneficial protective effects. We hypothesize that polarized arrest with esmolol/adenosine/magnesium (St Thomas' Hosp...

background & objectives: oral submucous fibrosis (osmf) is a condition where excessive deposition of dense collagen fibers occurred in the connective tissue of oral mucosa. an alteration of collagen necessitates an in depth understanding of collagen in oral tissues as no breakthrough studies have been reported. therefore the aim was to correlate the clinical, functional and histopathologica...