Biomedical subjects
Publications and source records attributed to G L Panattoni.
Transverse, frontal and sagittal notochord sections of chick embryos at different developmental stages were ultrastructurally examined. The notochord tissue organization appears to be more likely to build a stiff but flexible body axis than to have an inducting role on the surrounding embryonic structures.
Since in literature the question of the spatio-temporal sequence of the cartilage maturation in the developing vertebra is still controversial, the authors studied by light and electron microscope, the chondrification of the vertebral body in chick embryo from the 6th to the 13th incubation days, in order to define the correlations between morphology and distribution of the cartilage cells in this phase of vertebral development. The results show that the chondrogenesis follows spatio-temporal gradients, starting at about the 8th incubation day from a zone located between notochord and neural tube, slightly cranially to the midvertebral level. From this starting point the chondrification proceeds with dorso-lateral and radial progression, and at the same time extends towards the cranial and caudal plates of the developing vertebra. These data are compared to the findings obtained by other authors on the ultrastructural and biochemical aspects of the vertebral development.
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The proximodistal axonal transport of choline acetyltransferase (ChAc) has been studied in the chick sciatic nerve in the absence of any experimental manipulation. The phenomenon utilized by us is a physiological transient fall in the activity of ChAc. This fall occurs in most areas of the chick central nervous system after hatching, and moves toward the periphery along the nerves. Having ruled out the presence of transient inhibitors, the movement of the fall towards skeletal muscles has been considered to correspond to the proximodistal transport of ChAc. The calculated average velocity is 7.86 mm/day, corresponding to the slow rate of transport. Nevertheless, the kinematics study suggests that the velocity varies along the nerve from a state of rest to an intermediate rate of transport (16 mm/day). The possible influence of variations in the resistance of the conductor on these changes in velocity is discussed.
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The administration of desoxycorticosterone acetate (DOCA) induces morphological changes in the kidney of mice and eels. Such changes mainly concern the cells of the distal tubules and collecting tubules. These changes are consistent with the hypothesis that the hormone would exert a different action in Mammals and in Teleosts.
The authors focused their attention on the cytology of the degenerating notochord at the level of the vertebral anlagen and compared it with data of the literature on the histopathology of the spinal chordomas. The purpose of the research was to investigate the notochordal histological features justifying the fact that the remnants of a structure destined to atrophy during prenatal life, maintain a proliferative potential in postnatal life. Therefore, from the earliest stages (24th incubation hour) to the terms of development, the notochord was studied by electron microscope in chick embryo. The data obtained show that, in most notochordal cells, signs of metabolic damage and progressive degeneration coexist with signs of secretory and mitotic activity, from which the proliferative potential of these cells seems to derive. Vacuolar degeneration is also likely due to the progressive metabolic segregation of the notochord, owing to the absence of blood-vessels and the appearance of perichordal sheath.
The Author analysed the volumetric growth of the spine ("centra" + intervertebral discs) from the 13th week to term of prenatal life. The data were obtained from the osteological collection of the Department of Human Anatomy and Physiology (University of Turin), by means of a geometric procedure. The growth rate was compared with the observations of other Authors on the growth of the linear measures and with the results of previous works on the anteroposterior curvatures of the developing spine. The analysis of the growth in volume of the various spinal regions, seems to admit temporo-spatial relationships only between the growth velocity of the lumbar region and the appearance of the lumbar lordosis.
The Authors, on the basis of previous data obtained by ultrasonography, analysed more closely the quantitative and qualitative correlations between movements and spine development in the human fetus. The bending angles of cervical lordosis and thoracic kyphosis showed a trend directly and inversely proportional, respectively, to the trend of the overall motility of the fetus, measured as the percentage of time employed by the fetus in motor activity. The trend of the lumbo-sacral angle, that appears later, seemed to be less related to the motor behaviour of the fetus, while the bending angle of lumbar lordosis increases very rapidly when also the fetal motility shows an increase at 25-30 weeks. The significance that the developmental stages and the actions of the muscles involved in early fetal motility, and particularly in spine movements, have in the ossification and in the postural attitude of the axial skeleton, was finally discussed.
On the ground of data obtained in previous works, the trend of the various morphometric parameters, in particular of the body surface area/volume ratio (S/V), and the physio-pathological aspects of this problem, during the human fetal growth was analysed. The S/V ratio, that shows a rapid fall (92% of the initial value) during the 2nd and the 3rd months of development and later on trends to be more and more constant, is the expression of the changes of the shape, as well as the size of the fetus. These changes occur in the period of transition from embryonic to the fetal stage of development and affect the embryo-fetal termic stability, according to extent of the skin surface with respect to the unit of volume. Comparing these observations to the data of the literature, the Authors points out the significance of the S/V value in the radiant heat exchanges between the fetus and the developmental environment, and proposes this ratio for a parameter of the normal fetal growth.
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