Histochemical and ultrastructural data on the adrenergic and cholinergic innervation of the epididymis in the mouse

The adrenergic and cholinergic innervation of the epididymal duct in the mouse has been investigated using histochemical methods and electron microscopy. This study demonstrates that the epididymal innervation of the mouse does not really differ from that of other mammals. Cholinergic nerves are mainly vascular, even in the cauda where cholinesterase activity is increased within the tubular musculature. Catecholamine fibres ensure the motricity of the wall of the canalicular system, particularly the terminal segment where the smooth muscle fibres are specifically differentiated.     

Histochemical profiles of cat intrafusal muscle fibers and their motor innervation

Muscle spindles were examined histochemically in serial transverse sections of cat tenuissimus muscles. The myofibrillar adenosine triphosphatase (ATPase) staining reaction was used to identify nuclear bag1, bag2 and nuclear chain intrafusal muscle fibers. Regional differences in ATPase staining occurred along the bag1 and bag2 fibers but not along the chain fibers. All intrafusal fiber types displayed regional variability in staining for nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR). Motor nerve terminals were demonstrated along the poles of bag1, bag2 and chain fibers by staining for cholinesterase (ChE). There was no consistent spatial correlation between the intensity of regional ATPase staining along the bag fibers and location, number or type of motor endings. However, most ChE deposits occurred in intrafusal fiber regions that displayed the greatest NADH-TR variability. Some fiber poles or whole intrafusal fibers were devoid of any ChE deposits but their ATPase and NADH-TR content was comparable to that of fibers bearing ChE deposits. The observations suggested that motor nerve fibers per se may not play a major role in determining the histoenzymatic content of intrafusal fibers.     

Histochemical profiles of cat intrafusal muscle fibers and their motor innervation

Summary Muscle spindles were examined histochemically in serial transverse sections of cat tenuissimus muscles. The myofibrillar adenosine triphosphatase (ATPase) staining reaction was used to identify nuclear bag₁, bag₂ and nuclear chain intrafusal muscle fibers. Regional differences in ATPase staining occurred along the bag₁ and bag₂ fibers but not along the chain fibers. All intrafusal fiber types displayed regional variability in staining for nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR). Motor nerve terminals were demonstrated along the poles of bag₁, bag₂ and chain fibers by staining for cholinesterase (ChE). There was no consistent spatial correlation between the intensity of regional ATPase staining along the bag fibers and location, number or type of motor endings. However, most ChE deposits occurred in intrafusal fiber regions that displayed the greatest NADH-TR variability. Some fiber poles or whole intrafusal fibers were devoid of any ChE deposits but their ATPase and NADH-TR content was comparable to that of fibers bearing ChE deposits. The observations suggested that motor nerve fibers per se may not play a major role in determining the histoenzymatic content of intrafusal fibers.     

Regulation of postsynaptic alpha-1 adrenoceptors in smooth muscle of the cat nictitating membrane

Findings from radioligand research into smooth muscle in the cat nictitating membrane revealed the presence of specific [³H]prazosin binding sites corresponding to alpha-1 adrenoceptors. After smooth muscle sympathectomy, numbers of alpha-1 adrenoceptors rose without any significant change in their affinity. Incubating previously sympathectomized smooth muscle with noradrenaline led to a decline in the number of alpha-1 adrenoceptors — again without alteration in binding affinity. It was deduced that numbers of alpha-1 adrenoceptors are controlled by the sympathetic nervous system.S. V. Kurashov Medical Institute, Kazan'. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 735–741, November–December, 1989.     

The distribution of smooth muscle in the cat ovary with a note on its adrenergic innervation

Smooth muscle in the ovaries of estrus and anestrus cats was studied with the TP-Levanol Fast Cyanine 5 RN technique and adrenergic nerves were visualized with the Falck-Hillarp fluorescence procedure. Numerous bundles of smooth muscle fibers were observed in the mesovarium, and the hilar, medullary, and cortical regions of the estrus ovary. Also, theca externa of large vesicular follicles contained many smooth muscle fibers. Adrenergic nerves with varicosities were present in ovarian perifollicular tissue. Anestrus animals had a reduced number of cortical and perifollicular muscle fibers and the intensity and density of fluorescent nerves was reduced. It is suggested that contraction of ovarian smooth muscle facilitates ovulation. These contractions may be, at least partially, under local neural control.     

Histochemical and ultrastructural studies of the innervation of the lymph-vessel and blood-vessel wall. 1. Adrenergic innervation

The adrenergic innervation of the lymph vascular wall was studied by means of the Falck fluorescence histochemical tecnique and electron microscopy with Tranzer and Richards' histochemical tecnique. The lymph vessels wall, compared with that of blood vessels, shows very few adrenergic nerve fibers located in the adventitia outside the smooth muscle cells. The possible role of the nervous system in the motor control of the lymph vessels is discussed.     

Activation of the fast calcium input in the denervated smooth muscle of the cat nictitating membrane

The excitation and contraction features of innervated and sympathetically denervated smooth muscle strips from cat's nictitating membrane have been studied by single sucrose gap arrangement. Increasing of smooth muscle cells sensitivity to drugs were accompanied by elevation of membrane response and the ability to generation of action potentials. Action potentials have been induced by agonists or high potassium concentration in external solution and spontaneously. In innervated muscle action potentials have been evoked as a result of depolarization by high potassium concentration of TEA blockade of potassium conductance. Induced and spontaneously generated action potentials were blocked by organic and inorganic antagonists of potential dependent Ca++ channels. In Ca-free solution action potentials were absent but might be supported by Ba++. Decrease of Na+ had no effect on smooth muscle excitability. It is supposed that activation of potential depended Ca++ channels in smooth muscle cells with pharmaco-mechanical coupling are under influence of sympathetic nerves.     

Histochemical studies of noradrenergic innervation of the liver in untreated and daunomycin-pretreated guinea-pigs

Summary The pattern of noradrenergic innervation of guinea-pig hepatic tissue was examined by using the fluorescence method of Falk et al. (1962). The distribution of monoaminergic nerve fibres in untreated animals was clearly evident at the level of the portal vein, the hepatic artery and the bile duct. The hepatic artery was the most densely innervated. Mast cells and Kupffer cells had no connection with the adrenergic fibres. In daunomycin-pretreated animals, the hepatic cells appeared to be deep red in colour owing to the presence of the antibiotic. Some noradrenergic nervous fibres, never previously described, were unexpectedly distinguishable in the liver parenchyma against the background red colour of daunomycin-pretreated tissue. They appeared to be contiguous to the hepatocytes and were of different shapes: comma-like, V-like, or like a string of pearls. The nature and the functional role of these elements is briefly discussed.     

Control of rabbit nictitating membrane movements

The objective of this study is to understand more precisely the relationship of motoneuron activity to movements of the rabbit nictitating membrane (NM). We use a model of the oculomotor plant to investigate what NM movements are generated by a given pattern of neural input and what inputs are required to generate particular NM movements. Simulated peak NM extensions can occur well over 50 ms after the end of motoneuron activity. The neural input required for the model to generate full amplitude NM extension responses is more consistent with single accessory abducens unit recordings from awake rabbits than recordings from anesthetized rabbits. An initial high frequency burst of neural activity followed by a rapid decay is required for simulations of conditioned responses (CRs) trained at a 125 ms interstimulus interval (ISI). For CRs trained with a 250 ms ISI, a more slowly rising and decaying neural activity is required. Model simulations show that the linear correlation between the shape of histogrammed motoneuron activity and the shape of NM movements can be high for long duration responses (> 400 ms) but is low for short duration responses (< 200 ms). Simulations are also consistent with the hypothesis that NM retraction is generally passive.