The Classic: A Morphogenetic Matrix for Differentiation of Cartilage in Tissue Culture

This Classic Article is a reprint of the original work by Hiroshi Nogami and Marshall R. Urist, A Morphogenetic Matrix for Differentiation of Cartilage in Tissue Culture. An accompanying biographical sketch of Marshall R. Urist, MD is available at DOI 10.1007/s11999-009-1067-4; a second Classic Article is available at DOI 10.1007/s11999-009-1068-3; and a third Classic Article is available at DOI 10.1007/s11999-009-1070-9. The Classic Article is © 1970 by the Society for Experimental Biology and Medicine and is reprinted with permission from Nogami H, Urist MR. A morphogenetic matrix for differentiation of cartilage in tissue culture. Proc Soc Exp Biol Med. 1970;134;530–535

Order in Spontaneous Behavior

Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents

Organotypic modelling as a means of investigating epithelial-stromal interactions during tumourigenesis

The advent of co-culture approaches has allowed researchers to more accurately model the behaviour of epithelial cells in cell culture studies. The initial work on epidermal modelling allowed the development of reconstituted epidermis, growing keratinocytes on top of fibroblasts seeded in a collagen gel at an air-liquid interface to generate terminally differentiated 'skin equivalents'. In addition to developing ex vivo skin sheets for the treatment of burns victims, such cultures have also been used as a means of investigating both the development and repair of the epidermis, in more relevant conditions than simple two-dimensional culture, but without the use of animals. More recently, by varying the cell types used and adjusting the composition of the matrix components, this physiological system can be adapted to allow the study of interactions between tumour cells and their surrounding stroma, particularly with regards to how such interactions regulate invasion. Here we provide a summary of the major themes involved in tumour progression and consider the evolution of the approaches used to study cancer cell behaviour. Finally, we review how organotypic models have facilitated the study of several key pathways in cancer development and invasion, and speculate on the exciting future roles for these models in cancer research

RECEPTIVE-FIELD CHARACTERISTICS OF NEURONS IN A VISUAL AREA OF RABBIT TEMPORAL CORTEX

In a program of surveying the characteristics of visual receptive fields of neurons in rabbit brain, cortical sectors beyond the striate and occipital cortices were explored, and cells were found in a part of the temporal lobe that were responsive to visual stimulation. Using evoked potential and unit-cluster methods, this temporal visual area was mapped to be roughly oval-shaped, 3 mm .times. 2 mm in size, and at about the level posterior to the apex region of auditory area 1. It is located ventral to and continuous with visual area 11, at about the caudal half of Rose''s temporal cortices 1 and 2 (T1 and T2). Only about 2/3 of 96 units studied responded to some sort of moving light stimulation. These motion-sensitive cells were divided into 4 groups. Cells in the 1st group (22) responded best to a large light spot or shadow sweeping quickly across the field. Cells in the 2nd group (29) responded to slow moving, jerking spot. Nine cells responded to a narrow, dark bar thrust into a lighted field. Four cells were direction-selective, responding to a light stimulus moving in 1 direction and showing either no response or decreased background discharges in the opposite direction. In addition, 3 cells required unusual stimulus features. Of the 38 cells tested, 9 of them were binocularly driven. These receptive field characteristics were quite different from those described for other visual centers of the rabbit. The significance of these results together with data on the anatomical connections of this cortical area as reported in the following paper were discussed

NEONATAL SEPARATION: THE MATERNAL SIDE OF INTERACTIONAL DEPRIVATION

On page 197 of the February issue Dr. Barnett's name should have been spelled Clifford.</jats:p