The central representation area of the radial nerve in the goat, studied by the axon reaction.

The central representation area of the radial nerve has been investigated in the goat, using the axon reaction. The retrograde changes after a two or six weeks survival time have been used to study both its position and architecture. Reconstructions have been made using a computer assisted approach. In the goat the central representation area of the radial nerve is situated in the dorsolateral part of the lateral motoneuronal cell group, extending from caudal C6 to caudal T1. It begins very small in C6, enlarges through C7, reaches its maximal diameter in C8, from where it gradually decreases to end in caudal T1. The contribution of the C6 segment to the central representation area of the radial nerve in the goat is in agreement with findings in some other species but it contrasts with the macroscopic origin of the radial nerve in ruminants. It is suggested that this finding, together with the statistically significant reduction in the number of alpha motoneurons at the C6 level in calves affected with Arthrogryposis Multiplex Congenita (AMC) in the forelimbs, may prove an at least partial involvement of the radial nerve in the pathogenesis of this disease, which is also suggested by clinical symptoms.

Histo-anatomical backgrounds of subclavian flap aortoplasty in coarctation of the aorta.

After repair of coarctation of the aorta using the technique of resection and end-to-end anastomosis, the internal diameters of the aortic isthmus and descending aorta often fail to increase. Better results seem possible with aortoplasty using the left subclavian flap technique. In order to clarify this matter, we investigated the structure of the left subclavian artery comparing it with that of the descending aorta and aortic isthmus: we studied the internal diameter, the thickness of the tunica media and the packing density of its elastic fibers in these vascular elements using a postmortem material of children with a coarctation of the aorta. The ages ranged from 4 days to 13 months with one child of 8 years. All 16 cases had one or more additional cardiac lesions. Operation had been performed in 3 children: 2 end-to-end anastomoses and one subclavian bypass of the aortic arch. Data were compared with observations on autopsy cases of children without cardiovascular abnormalities. The mean findings were that the calibers of the left subclavian artery and the descending aorta were within normal limits but that the caliber of the aortic isthmus was smaller than in normal children. The measurements on the tunica media showed that although, generally, the thickness of the media of the left subclavian artery was smaller than that of the aortic isthmus and descending aorta of the same individual, it contained relatively more elastic fibers than the matching vessels. This may indicate that the structure of the left subclavian artery is well suited to grow out as a part of the aortic arch.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the growth of the tunica media of the ascending aorta, aortic isthmus and descending aorta in infants and children.

This study concerns the normal histological growth of the aorta in infants and children. We measured, in post mortem material consisting of 69 hearts and great vessels of infants and children who died from non-vascular diseases, the internal diameters of the ascending aorta, aortic isthmus and descending aorta together with the thickness of the tunica media and the packing density of its elastic fibres. Age range was from 27 weeks of gestational age up to 10 years after birth. The growth of the tunica media of the ascending aorta was, in part, different from that of the aortic isthmus and descending aorta. Notwithstanding an increase in the thickness of the tunica media parallelling, in all three parts of the aorta, an increase in their internal diameters, the packing density of the elastic fibres of the tunica media of the aortic isthmus and of the descending aorta showed no tendency to increase with age. However, the packing density of the elastic fibres of the ascending aorta showed a continuing increase with age parallelling the increase of the internal diameter. This can probably be better explained as a result of functional difference than as a result of different embryological origin.

Measurements of the descending aorta in infants and children: comparison with other aortic dimensions.

In paediatric cardiovascular surgery, knowledge of internal diameters along the first part of the aorta is essential. This paper presents reference data on the internal diameters of aortic ostium, ascending aorta, aortic isthmus and descending aorta, 1 cm distal to the ductus arteriosus. Measurements were made with the aid of calibrated probes in 126 post mortem specimens of normal hearts with great vessels. The age range was from 25 weeks of gestation up to 10 years after birth. The data revealed linear correlations between the internal diameters of the different parts of the aortic arch and body length. At variance with the literature, we found that, with few exceptions, the internal diameter of the ascending aorta was greater than that of the descending aorta.

Changes after birth in the tunica media and in the internal diameter of the aortic isthmus in normal newborns.

In 104 hearts of infants and children, who died from non-vascular diseases, and whose ages ranged up to 10 years after birth, narrowing of the aortic isthmus, i.e. an internal diameter of 80% or less of that of the descending aorta, was found in 26 cases (24%). The remaining cases showed a lesser degree or no narrowing of the aortic isthmus. Among the 38 cases who died within 2 days after birth (gestational age range 21 to 42 weeks) narrowing of the aortic isthmus, as defined above, was present in only 14 cases (37%). This is much less frequent than is suggested in the literature. No correlation was found between presence, and degree, or absence of narrowing of the aortic isthmus and the relative sizes of the aortic and pulmonary narrowing of the aortic isthmus and the relative sizes of the aortic and pulmonary ostia. Possibly, to define the limits of the normal condition of the aortic isthmus, not only its diameter, but also the characteristics of its tunica media may be of importance. Therefore, the thickness and the packing density of the elastic fibres of both the aortic isthmus and the descending aorta were measured in 69 cases, equally distributed over the material. It is reasoned that in the 3 out of a total of 26 cases, in which not only a marked narrowing of the aortic isthmus was observed but also a relative underdevelopment of its tunica media, a persistent narrowing might have developed, whereas development of such a persistent narrowing seems less likely with a tunica media of normal volume and structure.

Normal internal calibres of ostia of great arteries and of aortic isthmus in infants and children.

In order to obtain reference data, useful in paediatric cardiology and paediatric cardiovascular surgery, internal diameters of the ostia of the great arteries, of the aortic isthmus, and of the descending aorta were determined with the aid of calibrated probes in 46 necropsy specimens of normal hearts with great vessels. Age range was from 25 weeks of gestational age up to 9 years post partum. The method used proved to be as accurate as echocardiography in vivo. The data revealed linear correlations between body length and calibres of aortic and pulmonary ostia. The correlation between the calibres of the pulmonary and the aortic ostia was also a linear one with the pulmonary ostium being slightly larger than the aortic ostium. From the cross-sectional areas of the aortic isthmus and of the descending aorta an isthmus index was calculated which indicates the presence (and degree) or absence of a narrowing (tubular hypoplasia) of the aortic isthmus. Results show that narrowing of the aortic isthmus is inconstantly present in infants younger than 10 weeks, whereas it is always absent in infants and children older than 10 weeks. No dependence of narrowing of the aortic isthmus on developmental age attained at birth has been found.

Coronary and endocardial fibroelastosis of the ventricles in the hypoplastic left and right heart syndromes.

In an autopsy material of 29 cases of the hypoplastic left heart syndrome coronary fibroelastosis was found in 1 case, endocardial fibroelastosis in 8 cases. Figures for 10 cases of the hypoplastic right heart syndrome were 6 cases of coronary fibroelastosis and 1 case of endocardial fibroelastosis. Age ranged from stillborn up to 11-1/2 months. Coronary and endocardial fibroelastosis seemed to be mutually exclusive localizations of congenital fibroelastosis since in our material they did not occur together in the same hearts. In hypoplastic right hearts coronary fibroelastosis was either restricted to the right coronary artery (right circumflex and posterior interventricular branch), or it was found also in the left coronary artery (anterior interventricular branch), with the most serve affections always being situated in the right one. In the only case of coronary fibroelastosis among the hypoplastic left hearts the condition was limited to the anterior interventricular branch of the left coronary artery which communicated with the hypoplastic left ventricle by a fistula. Coronary fibroelastosis was exclusively found in branches supplying the hypoplastic right ventricle and/or in a branch connected by a fistula to the hypoplastic left or right ventricle. Endocardial fibroelastosis was generally found in hypoplastic left ventricles with either no outflow or with severe outflow obstruction. A theory concerning the aetiology of both coronary and endocardial fibroelastosis of the hypoplastic ventricles is proposed. It is argued that development of fibroelastosis may in both localizations be caused or favoured by the coincidence of two factors: abnormal haemodynamic conditions and poor oxygenation of blood and tissues. Observations made in a reference material of 35 hypoplastic left and 24 hypoplastic right hearts were in accordance with this view.