The role of relative osteoneural growth in the gross morphogenesis of the skeleton: A hypothesis

The properties of the nervous system and the two-growth-types (egg-sperm) concept of carcinogenesis

Some common morphological and functional features of the sperm and of the neuroblast (above all the resistance of the egg once fertilized to penetration of further sperms and of the embryonic cell once innervated to additional innervation) point to their developmental relationship, viz. to continued existence of the sperm, following temporary disappearance and genetic interaction within the egg, in the form of a neuroblast. The egg and the sperm would thus give origin to the two basic growth types of the vertebrate body, viz. the cellular-divisional (of the non-nervous tissues) related to the egg and the neural-extensive originating in the sperm and characterized by sprouting of processes even several decimeters long from a single nerve cell body. The nervous system, in addition to its intricate functions, represents an extremely dense feltwork of nervous trunks, branches and fibres, the 'nervous skeleton' (6), the product of the extensive neural growth which is 'stuffed' with the products of the cellular divisional proliferation of the other, non-nervous tissues. The absence of nerves (or of normal nerves) within the malignant tumours points to cellular 'escape' from the limiting confines of the nervous skeleton as the biological cause of malignancy: the 'escaped' cells pursue the one-growth type way of life instead of the normal two-growth-types way, viz. they revert back towards the egg-condition and acquire embryonic features. Introduction of neuroblasts into the malignant tumour aimed at re-establishment of its nervous skeleton should convert the malignant lesion into a benign one.

Campomelic syndrome: experimental models and pathomechanism

Experimental teratogenic models of the campomelic syndrome in duck and chick embryos and in frog tadpoles are presented. The association of selective growth impairment of the peripheral and facial nerve trunks including the spinal cord and nerve roots is suggested as an underlying cause for adaptive shortening of the corresponding skeletal parts. Buckling may occur because the growing bones tend to accommodate to these underdeveloped neurological structures even at the cost of a deformity. It is suggested that investigation of the effects of "skeletal" teratogens upon the nervous system may be more logical than concentrating upon bone growth which may be the secondary effect.

Cranio-cervical growth collision: another explanation of the Arnold-Chiari malformation and of basilar impression

Analysis of neuro-cranio-spinal development suggests a cranio-cervical growth conflict as the cause of the Arnold-Chiari malformation and of basilar impression. The ascending course and elongation of the upper cervical nerves associated with the Arnold-Chiari malformation reflects the abnormal, caudo-cranially proceeding growth of the cervical spine. This is the opposite of the normal cranio-caudal direction of growth (which includes the brain) with downward slanting of the cervical nerve roots. The cervical growth reversal is a compensatory event related to the impairment of distal spinal growth at the level of the coexistent myelomeningocele. With the reversal of the cerical growth, the initial descent (uncoiling) of the primordial brain curvatures is compromised owing to the growth-collision with the ascending cervical spine. Their subsequent growth proceeds into the upper cervical spinal canal. The contents of the posterior cranial fossa are actively "sucked up", "devoured" by the latter. In contrast to the adaptively enhanced growth of the early cranio-cervical nervous structures in the Arnold-Chiari malformation, as an answer to the growth-shifts of the encasing skeleton, basilar impression is a postembryonic adaptation of the cervico-cranial skeleton to the inadequate growth of the nervous structures after the latter have lost their growth adaptability. Arnold-Chiari malformation and basilar impression are just two representatives of "osteo-neural growth pathology" encompassing some "dysplastic" disorders of the axial as well as of the limb skeleton such as platyspondyly, scoliosis, Scheuermann's kyphosis, achondroplasia-like conditions, congenital dysplasia of the hip etc.(ABSTRACT TRUNCATED AT 250 WORDS)