[Experimental skeletal teratogenesis: a disturbance of relative osteo-neural growth]

The previously suggested concept of the closest growth relations existing between the bony and the nervous tissue at the organ level of the spinal cord and the peripheral (including the facial) nervous trunks is experimentally buttressed. It is shown that the normal gross-morphological features of the vertebrae as well as of the tubular bones (viz., their length, physiological curvatures and terminal expansions) result from the adaptation of the bone growth to the slower proceeding and vulnerable neural extensive growth, viz., from a physiological osteo-neural growth disproportion. The more or less conspicuous growth in length of the facial skeleton depends upon the phylogenetically established, more or less evolved extensive-growth potentially of the facial nervous trunks as well. The growth relation existing between the developing brain and its bony case applies essentially even for the axial organ, the extremities as well as for the facial skeleton. The experimental findings speak in favour of the theoretical expectation that the typical teratogenic deformities of the extremities (micromelia), of the spine (scoliosis, defects of the vertebrae and of the ribs) as well as of the beak (jaws) which may be produced by a great number of most diverse teratogens, result from the adaptation of the bone growth to the growth-insufficient nervous trunks, viz., from the pathologically enhanced osteo-neural growth disproportion. The cleft palate and the digital defects (syndactylia, oligodactylia) may be readily explained by the growth-inhibition of the palatal and digital nervous structures as well. The vertebrate body may be thus conceived as composed of 2 growth types, viz., the neural-extensive and the cellular-divisional (mitotic). The former is represented by an extremely dense feltwork of nerve fibers and trunks (the DONALDSON'S "nervous skeleton") which is "stuffed" with the other, mostly mitotically growing tissues. The 2 growth types are closely related partly at the macro-(organ-) level concerning the normal and teratogenic morphogenesis of the skeleton, partly at the micro-level of the utmost periphery, viz., of the terminal extensive meshwork and the individual cells or groups of cells. The cells which escape from the extensive feltwork (i.e. from the "nervous skeleton") such as the superficial cells of the epidermis or mucous membranes and, in all probability, the elements of the haemopoetic organs, perish under normal conditions, suffer a planned, highly purposeful death. With regard to the lack of normal nerves within malignant tumours, the malignant cell may be conceived as the one which escaped from the limiting confines of the extensive feltwork and, inspite of that, continues to live instead of "committing suicide."