Variability in the myeloarchitectonics of the nerves of the thyroid arteries during postnatal human development

Serial transversal sections on the nerve-vascular complexes of four thyroid arteries in newborns, in persons of the 1st and 2d periods of mature age, in elderly and old persons (40 complexes in each age group) are stained after Weigert--Pahl. Amount of myelin fibers (MF) of three dimensional classes are defined micromorphometrically. Total amount of the MF in the nerves of all thyroid plexuses is the greatest in the persons belonging to the second mature period of age: it is 2.7 times as great as in the newborns. In the elderly persons it is 1.5 times, and in the old persons--1.8 times as little as in the persons of the second period of maturity. Thin MF make the absolute majority. The amount of the MF with middle caliber in the thyroid nerves of the mature persons is 6.6 times as great as in the newborns. Their amount in the old persons is 1.7 times as little as in the mature persons. Thick MF are absent in the newborns; in the mature and elderly persons they are observed now and then. The thick MF are characterized by a high variation coefficient (up to 84%). According to the criteria of absolute and relative contents of both total and group composition of the MF in postnatal period, three stages in development of the thyroid innervational connections performed by the MF are revealed: productive, stabilization and involution. The correlative analysis reveales a direct dependence in the system diameter of each thyroid artery--number of the MF in nerves of its plexus in the newborns and mature persons. This dependence becoms negative in the elderly and old persons.(ABSTRACT TRUNCATED AT 250 WORDS)     

Age and features of the content of myelinated fibers in nerves of the splenic plexus of man

The amount of the myelin fibers (MF) has been calculated in transversal serial sections of the nervous-vascular complexes of the splenic artery in newborns, in persons of mature (the 1st and 2d periods), elderly and old ages. In each age group 20 complexes have been studied. The total amount of the MF in persons of mature age (the 1st period) in 4.2-6 times greater (initial--terminal parts of the plexus) than in newborns, in the persons of old age it is 4-2.1 times less than in persons of mature age (in both cases P less than 0.001). Thin MF predominate, their relative contents in the aggregate of all classes of the MF in newborns are 92%, in mature persons--87%, in old persons--65%. Decreasing part of the thin MF together with increase of their absolute amount in the mature persons, comparing to the newborns, depends on higher rates in differentiation of middle and thick MF. Phenotyping peculiarities and stages of productive development, stabilization (the 1st-2d periods of the mature age), involutions of the nerve connections are defined in the splenic artery. The amount of the MF predominates in the nerves of the initial part of the plexus comparing to its terminal part. There is a direct correlative dependence between the amount of the MF in the plexus nerves and the size of the lumen in the splenic artery. Changes in the amount of the MF of different classes reflects qualitative differences of the splenic innervation relations at certain stages of the human postnatal development.     

Distribution of acetylcholinesterase-positive nerve fibers in the wall of the great saphenous vein in women

A relative density of acetylcholine esterase-reactive fibers in adventitium of the large subcutaneous vein changes in the postnatal ontogenesis in women: it is the lowest in newborns, the greatest in mature women, in old women it grows small. In newborns these fibers are situated in the compact layer of the adventitium, in mature and old women they are revealed in interlayers of the connective tissue that separate fasciculi of muscle fibers of the external longitudinal and internal circulatory layers of the middle sheath.     

Age-related characteristics of the myeloarchitectonics of the peripheral nerves

By means of macromicroscopy and microscopy myeloarchitectonics of morphologically and functionally different somatic and visceral nerves (branches: mandibular nerve, cervical spinal nerves, inferior laryngeal nerve, hepatic plexus) have been studied in 11 age groups. During the prenatal period of ontogenesis asynchronism of myelogenesis is stated in various muscle branches of the nerves, dependent on formation of function in corresponding muscles and muscle groups. As demonstrate investigations on peculiarities of myelogenesis course in the somatic and visceral nerves studied, during the period of pre- and postnatal ontogenesis, its dynamics embraces three stages of myelogenesis, determined by G. B. Stovichek for visceral nerves: productive myelogenesis, stages of stabilization and involution. The stage of productive myelogenesis in the somatic nerves studied lasts up to the end of the adolescent period. Two phases are determined in it: the first lasts up to 2-3 years; the second--up to the end of the adolescent period and is characterized with a complete formation of the myelin fibers spectrum. In the visceral nerves studied increase of general amount of myelin fibers and their differentiation are completed simultaneously during the adolescent age. The stabilization stage of myeloarchitectonics of the nerves studied corresponds to the mature age (I and II periods) and the involution stage--to the elderly (and old) age.     

Myeloarchitectonics of the vagus nerve in man

In serial electively stained transversal sections of the vagus nerve trunk taken at the levels beginning from its exit out of the brain, up to terminal branches in the abdominal cavity (10 corpses of mature persons) myelin fibers of three classes have been counted. Along the course of the nerve trunk in the craniocaudal direction the total number of the myelin fibers decreases. Only about 10% of the initial amount of the myelin conductors revealed at the level of the intracranial part of the vagus nerve get into the abdominal cavity. Simultaneously, the ratio of the myelin fibers belonging to different classes changes: the part of the fine conductors increases, and that of the fibers having middle and large diameters decreases. The most important in the dynamics of the whole amount of myelin fibers and in the number of the conductors belonging to different classes at all the levels of the nerve trunk is the getting off the organs' branches with various functional specialization.     

Age and the extent and topography of solitary lymphoid nodules in the wall of the human small and large intestine

Amount and topography of small lymphoid nodules (SLN) have been studied by means of the quantitative method in flat total preparations of the small and large intestine obtained from 111 corpses of persons of both sex (from newborn up to old age). Total amount of the SLN in the large intestine wall in all age periods exceeds that of the SLN in the small intestine wall. From birth up to the period of the 1 childhood total amount of the SLN increases successively, reaching (51 +/- 14) X 10(2) in the small and (74 +/- 11) X 10(2) in the large intestine at the age of 4-7 years. Beginning from 8 years of age up to old age, total amount of the SLN decreases successively, to a more degree in the wall of the small intestine than in the large intestine. The arrangement density of the SLN in the large intestine wall essentially exceeds that of the SLN in the small intestine wall during the all age periods. From birth up to early childhood the arrangement density of the SLN increases and then gradually decreases both in the small and large intestine. This demonstrates that development of the SLN takes place during the first 4-7 years of the human life, in contrast to the lymph nodes and tonsils, their greatest development takes place during juvenile and adolescent age.     

Development of various types of muscle fibers in the quadriceps femoris and the soleus during human ontogenesis

By means of histological methods for revealing adenosine triphosphatase of myosin (pH 4.6) and succinate dehydrogenase activity, using postmortem material, development of various muscle fibers of the femoral m. quadriceps and m. soleus has been studied in human ontogenesis. The first stage of rearrangements lasts from the 5th-6th month of the uterine development up to 2 years of age and is characterized by formation (from non-differentiated) of oxidative, glycolytic and oxidative-glycolytic fibers. During the period from 2 up to 7-8 years of age the ratio in the types changes slightly, but transversal section size of the muscle fiber increases intensively. Then from 11 up to 17 years of age, together with maximal increment of the fibers transversal section, there is an essential change in the type relation. By the 17th years of age, in the femoral m. quadriceps the part of the fibers with glycolytic type of energy supply increases, while in the m. soleus the oxidative fibers become more numerous. By the 70th years of age in the femoral m. quadriceps relative amount of intermediate fibers increases.     

Intracranial portion of the trochlear nerve and dorsal oblique muscle composition in dog: a structural and ultrastructural study

In the present investigation the right intracranial portion of the trochlear nerves and dorsal oblique muscle of the right ocular globe were removed from six adult dogs and analyzed by light and electron microscopy. Unmyelinated fibers were observed in the analyzed nerves. The number, diameter, area, and density of myelinated fibers were determined, as were corresponding axon area and diameter and myelin sheath thickness. Frequency histograms of myelin sheath thickness and fiber size show a bimodal distribution with a similar proportion of large and small fibers. Muscle samples were taken from the central portion of the muscle belly, subsequently frozen, cut, and stained with m-ATPase at pH 4.6. Fibers were classified as Type 1 or Type 2 according to their reaction to the m-ATPase and detailed morphologic and morphometric studies were made. The muscles showed two clearly distinct layers, a central layer and a peripheral layer, chiefly composed of Type 2 fibers. The fibers in the central layer were larger in size than those in the peripheral layer.     

Sequence of Age-Associated Changes to the Mouse Neuromuscular Junction and the Protective Effects of Voluntary Exercise

Loss of connections between motor neurons and skeletal muscle fibers contribute to motor impairment in old age, but the sequence of age-associated changes that precede loss of the neuromuscular synapse remains uncertain. Here we determine changes in the size of neuromuscular synapses within the tibialis anterior muscle across the life span of C57BL/6J mice. Immunofluorescence, confocal microscopy and morphometry were used to measure the area occupied by nerve terminal synaptophysin staining and postsynaptic acetylcholine receptors at motor endplates of 2, 14, 19, 22, 25 and 28month old mice. The key findings were: 1) At middle age (14-months) endplate acetylcholine receptors occupied 238±11 µm² and nerve terminal synaptophysin 168±14 µm² (mean ± SEM). 2) Between 14-months and 19-months (onset of old age) the area occupied by postsynaptic acetylcholine receptors declined 30%. At many endplates the large acetylcholine receptor plaque became fragmented into multiple smaller acetylcholine receptor clusters. 3) Between 19- and 25-months, the fraction of endplate acetylcholine receptors covered by synaptophysin fell 21%. By 28-months, half of the endplates imaged retained ≤50 µm² area of synaptophysin staining. 4) Within aged muscles, the degree to which an endplate remained covered by synaptophysin did not depend upon the total area of acetylcholine receptors, nor upon the number of discrete receptor clusters. 5) Voluntary wheel-running exercise, beginning late in middle-age, prevented much of the age-associated loss of nerve terminal synaptophysin. In summary, a decline in the area of endplate acetylcholine receptor clusters at the onset of old age was followed by loss of nerve terminal synaptophysin from the endplate. Voluntary running exercise, begun late in middle age, substantially inhibited the loss of nerve terminal from aging motor endplates.     

Developmental changes at the node and paranode in human sural nerves: morphometric and fine-structural evaluation

Developmental alterations of paranodal fiber segments have not been investigated systematically in human nerve fibers at the light- and electron-microscopic level. We have therefore analyzed developmental changes in the fine structure of the paranode in 43 human sural nerves during the axonal growth period up to 5 years of age, and during the subsequent myelin development up to 20 years and thereafter. The nodal, internodal, and paranodal axon diameters reach their adult values at 4–5 years of age. The ratio between internodal and paranodal axon diameters remains constant at 1.8–2.0. Despite a considerable increase in myelin sheath thickness, the length of the paranodal myelin sheath attachment zone at the axon does not increase correspondingly, because of attenuation, separation from the axolemma, and piling up of myelin loops in the paranode. Separation of variable numbers of terminal myelin loops from the underlying axolemma results in the formation of bracelets of Nageotte, whereas the transverse bands of these loops disappear. The adaptation of the paranodal myelin sheath to axonal expansion during development probably occurs by uneven gliding of the paranodal myelin loops simultaneously with internodal slippage of myelin lamellae. Since mechanically stabilizing structures (tight junctions and desmosomes between adjacent paranodal myelin processes; transverse bands between myelin loops and paranodal axolemma) are unevenly arranged, especially during rapid axonal growth, paranodal axonal growth with simultaneous adaptation of the myelin sheath is probably discontinuous with time.Presented in part at the 10th Biennial Meeting of the Peripheral Nerve Study Group at Arden House, Harriman, New York, USA, June 30th–July 3rd, 1991, and as a doctoral thesis (M. Bertram) at the RWTH Aachen in 1991     

Changes in the intramural neural apparatus of the stomach and gallbladder in the late periods after vagotomy

By means of morphological methods changes in the wall of the stomach central part and in that of the bile bladder have been studied in 15 patients after a remote vagotomy (in 7-17 years). Material of biopsies and resections has been investigated. In the wall of the organs in question focal and diffuse mono- and plasmocytic infiltrates, leucocytic invasion of the mucous membrane epithelium, microerosions, microfocal hemorrhages in the external layers of the muscular sheath have been revealed. Inflammatory-degenerative and dystrophic changes are observed in the intramural ganglia, in large and small fasciculi of the muscular-intestinal nervous plexuses. In the tissues of the organs studied there are no myelin fibers, that are ++pre-ganglial and receptor conductors. The degeneration of these fibers after vagotomy and loss of connections in the organs investigated with the CNS are supposed to result in essential changes not only of the nervous trophic of tissues in all membranes and sheaths, but bring about changes in the intramural nervous apparatus itself. These changes, in their turn, cause imbalance + in the neurogumoral regulation and can be considered as the base of a number of postvagotomic structural-functional disturbances.     

Electrical activity and structural correlates of giant nerve fibers in Kuruma shrimp (Penaeus japonicus)

Morphology and recordings of electrical activity of Kuruma shrimp (Penaeus japonicus) giant medullated nerve fibers were carried out. A pair of giant fibers with external diameter of about 120 μ and 10 μ in myelin thickness were found in the ventral nerve cord. The diameter of the axon is about 10 μ. Thus there is a wide gap between the axon and the external myelin sheath. Each axon is doubly coated directly by Schwann cells and indirectly by the myelin sheath layer which is produced by those Schwann cells. Impulse conduction velocities of these giant fibers showed a range between 90–210 m/sec at about 22°C. Large action potentials (up to 113 mV, rise time of 0.16–0.3 msec, maximum rate of rise of 650–1250 V/sec, half decay time of 0.2–0.3 msec, maximum rate of fall of 250–450 V/sec and total duration of less than 1.5 msec) could be obtained by inserting microelectrodes or by longitudinal insertion of 25 μ diameter capillary electrodes into the gap but no DC-potential difference was observed across the myelin sheath. Transmyelin electrical parameters were very favorable for fast impulse conduction: myelin resistance of 3 × 10⁴ Ω cm²; time constant of 0.38 msec; myelin capacitance of 1.35 × 10^?8 F/cm²; gap fluid resistivity of 23 Ω cm. The existence of nodes of Ranvier could not be demonstrated morphologically, but electrophysiological evidence suggests that a type of saltatory conduction occurs in these giant fibers.     

Formation of structuro-functional units of the microcirculatory bed of muscles in the postnatal period of the ontogenesis of the white rat

By means of biomicroscopy, histological methods and scanning electron microscopy topological relationships between the white rat m. cremaster microvessels and changes of their spatial organization have been studied in the postnatal development beginning from the 3d to the 14th week. In the terminal link of the microcirculatory bed zonal functional complexes of microvessels--myoangions are revealed. They represent rather autonomic and regularly repeating constructions of microvessels, having spatial regularity in respect to muscle fibers. With age the myoangion increases its stretchness from 303 +/- 14 in 3-week-old up to (70 +/- 3) X 10 mcm in 14-week-old animals. Capillary density in the m. cremaster during the development decreases from 354 +/- 12 up to 210 +/- 4 mcm, respectively. Distance between the longitudinal capillaries increases from 16.1 +/- 1.3 up to 31.2 +/- 1.8 mcm. Increase of transversal connections takes place in the capillary network, increasing number of the branching knots; this demonstrates certain complication of the nutritive link of the muscle microcirculatory bed. By the time of sexual maturation (6 weeks) there is a sharp decrease of the inflow and outflow coefficients. Higher meanings of the coefficient (0.70-0.74) are noted before sexual maturation period in comparison to that in mature animals (0.53-0.55).     

Lymphoid nodules of the urinary bladder in man

Basing on macro- microscopical investigation of the urinary bladder in 94 persons, died at the period of birth up to old years and by the time of death having not any disease of the urinary apparatus, structure and topography of the lymphoid nodules, their amount, density of distribution in the mucous membrane of various parts of the organ have been studied. The germinative centers in the lymphoid nodules of the urinary bladder are not revealed. The external appearance of the nodules is not the same; some have clear contours others have no clearly manifested borders. We call them prenodules. The lymphoid nodules are situated near to each other without any definite order. And only near the ureteral openings they are always revealed in a small amount, in the area of the triangle; they are oriented, as a rule, from the ureteral openings towards the exit from the urinary bladder. The amount of the lymphoid nodules in the organ's wall varies (at an average) from 18, in newborns, up to 415, in adolescents, and up to 129, in old persons. Distribution density of the lymphoid nodules in the fundal area of the urinary bladder is somewhat greater, than in its superior parts. The size of the lymphoid nodules during all age periods is not more than 900 mcm.     

Formation of the muscular and neural components of the femoral artery wall of the dog in early postnatal ontogeny (an ultrastructural and histochemical study)

In puppies of various age (newborn, 2-week-old. 1- and 3-month-old) formation of smooth muscle and neural components in the femoral artery wall has been studied electron microscopically and histochemically. As demonstrate the electron microscopic data, the femoral artery wall is mainly formed by birth, nevertheless, structural components of its each tunic are at various stage of maturation and only by the 3d month the differentiation and specialization process of all cellular elements is fully completed. Owing to a combination of techniques used, it has been possible to follow the dynamics in formation of the innervation apparatus of the femoral artery. In the newborn animals the adrenergic apparatus of the femoral artery is presented mainly as thick fibers of a cable type; they form a plexus with loose loops at the periphery of the external tunic. Varicosities are scanty. By the 3d month there is a well developed network of the adrenergic fibers at the border of the middle and external vascular tunics. Some terminals penetrate into the muscular tunic. There is a great number of varicosities in the neural fiber axons. At the border of the middle and external tunics of the vessel, complex neuro-muscular interrelations are forming with an aim to bring functionally closer the main structural components of the wall. In the course of the early postnatal ontogenesis in dogs up to 3 months of age, in the femoral artery wall certain processes take place directed to ensure the neuroregulatory vasomotor properties of the vessel.     

Development of different types of muscle fiber in the postnatal ontogeny of guinea pigs

As demonstrates estimation of myosin ATPase and SDG activity, the guinea pig is already born with differentiated muscle fibers (MF), and the first histochemical differences between them take place in the uterine 10 days before birth. Tonic oxidative fibers of the first type, arranging hexagonally, develop especially quickly at early stages of postnatal ontogenesis. Their relative contents up to the end of the observations (185 days) do not change, and area of their transversal section increases but slightly in comparison to the phasic fibers. The main age changes of the muscle tissue are connected with formation and rearrangement of the phasic fibers. The most intensive reconstructions of the phasic fibers coincide with the period of game activity and sex maturation. In mixed muscles the part of the glycolytic fibers increase during the postnatal ontogenesis. In the process of ontogenesis the soleus muscle fully consists of oxidative fibers. The definitive level of the MF development is established after the guinea pigs have reached their sex maturation. Comparing the results of the given investigation with the previous data on development of MF in rats, it is possible to conclude that term and premature animals have various rates in development of the muscle system, however, main stages of myogenesis coincide, though they are connected with various phases of ontogenesis.     

Intrinsic nerves of the pectoralis major and minor in man

In the human intraorganic nerves of the thoracic muscles amyelin fibers make 62% and myelin ones--38%. In transversal sections ultrastructure of the myelin and amyelin fibers varying in their diameters has been studied. In the myelin and amyelin fibers the amount of various organells is not equal: in the amyelin fibers the arrangement density of microtubules is greater than that of neurofilaments, there is a reverse dependence between the amount of the microtubules and the neurofilaments on the one hand, and the fibrilar diameter, on the other hand. In the myelin fibers with the increasing diameter, the amount of the neurofilaments increases, while that of the microtubules decreases.     

Histochemical characteristics of the muscle fibers of the biceps and triceps brachii muscles in human ontogeny

By means of morphometrical and histochemical methods for revealing myosin ATPase and SDG activity development of various types of muscle fibers (MF) has been studied in the postmortem material, using m. biceps and m. triceps brachii in human ontogenesis. The flexors and extensors have features in common in the dynamics of the MF maturation, and some distinctive peculiarities. The appearance of histochemical distinctions between the MF takes place on the 5th-6th months of the intrauterine development. Morphofunctional specialization begins with formation of tonic fibers. During the 1st-2nd years phasic fibers form. A relative amount of fast MF in both muscles increases at the age of 11-12 years. The dynamics of final specialization of the MF is connected with stages of sexual maturation. The first stage of the sexual maturation (about 14 years of age) is connected with decrease in the relative amount of the MF of glycolytic type of energy supply and corresponding increase in the number of oxidative type structures. From 15-17 years of age a final differentiation begins, it is connected with an intensive transversal growth of all the MF and distinguish of thick glycolytic MF. The m. biceps brachii has a relatively greater amount of oxidative fibers, and the m. triceps brachii, glycolytic ones. The transversal section area of the MF in the m. triceps brachii exceeds that of the m. biceps brachii, beginning from the 7th month of the intrauterine development up to 14 years of age. The investigation performed does not reveal any anticipating development either in the flexors or in the extensors. The differentiating processes in the m. biceps and m. triceps brachii occur nearly simultaneously.     

Characteristics of the ensemble organization of the human cerebral cortex from birth to 20 years of age

When studying frontal, somatosensory and visual areas of the human cerebral cortex from birth up to 20 years of age in year-to-year intervals, it has been stated that by birth in neocortex all components of the neuron-glio-vascular ensembles are presented. They are not connected in their composition. During the first year of life the size of all types of neurons increases, long-axonal basket neurons differentiate, fasciculi of radial fibers become thick. By 3 years of life in the ensembles the neurons are definitely grouped as clusters. Sizes of spindle-like and satellite neurons increase; they distribute their axonal collaterals vertically, horizontally and in frontal-posterior direction. By 5-6 years of age the horizontal connection system becomes more complex at the expense of longitudinal growth and ramification of lateral and basal dendrites of the pyramidal neurons. In the section transversal areas occupied with cell groups increase. By 9-10 years of age the pyramidal neurons reach their greatest size. By 12-14 years of age the fibrillar component of the cortex increases considerably, inter- and intraensemble horizontal connections become more complex, the system of local connections becomes more plastic owing to development of short-axonal basket-like neurons. By 16-18 years of age the ensemble cortical organization in its main parameters of architectonics reaches the level specific for mature persons.     

Development of the female mammary gland at young ages (morphometric data)

By means of a developed method of histotopographical sections cartograms, 146 preparations obtained from female persons at the age of 8-25 years have been studied. The organ is intensively developing not only at 12-16 years of age, but at 22-25 years, as well. A close correlation is noted at 10-11 years of age between the mammary gland mass and the degree of its parenchyma (glandular tree) development. Subsequently, the connection between these indices becomes essentially weaker. At the age of 15-25 years, according to the variability and standard deviation quantile classes reflecting stages in the organ formation (the degree of the glandular tree development), five types of the mammary gland are distinguished: weak, low middle, middle, high middle and high. During transition of the mammary gland from the weak to the high type, at first the glandular tree is intensively developing in the periphery and in the internal parts, and then in the external squares and in the center of the organ. The degree of uneven development in the glandular tree increases when the middle type is reached. Subsequently, it decreases up to the initial level.