Small Ganglion Research Articles

Role of the intramural ganglion cells played in the motility of the large intestine of the tortoise, Geoclemys reevesii

The development of the intramural plexuses in the tortoise, Geoclemys reevesii was inferior to that observed in the fowl: the meshes of both Auerbach's and Meissner's plexuses were coarser, and consisted of less number of nerve fibers. Occasionally, a small ganglion was seen at the crossing points of the meshes. The average number of nerve cells contained in the ganglion was estimated to be 1500/cm2, being about half as much as that estimated in the fowl. When the mucosa of a colon in vitro was stimulated mechanically by stroking or chemically with 1/10 N HCl, the excitability of the colonic muscle was raised at the region oral to the stimulated spot, but lowered at the region anal to it. These effects were abolished by applying a ganglion-blocking agent, hexamethonium (10(-6) g/ml), to the mucosa. When the intraluminal pressure of a colon in vitro was raised from 0 to 3-12 cm H2O, the colon was distended at first but soon contracted powerfully. The contraction became extremely reduced or was abolished when hexamethonium (3.5X10(-7) approximately 1X10(-5) g/ml) was added to the saline solution in which the colon was immersed. The results indicate that the intramural ganglion cells serve as the center of the intrinsic mucosal reflex.

Peripheral neurosecretory cells in some Lepidoptera

A segmental series of peripheral neurosecretory cells was found in larvae of some Lepidoptera. They occur in the thoracic segments and in the first eight abdominal segments, towards the distal end of the transverse nerves. In the thorax, and in abdominal segments 1, 2, and 8 there is usually a single cell, but in abdominal segments 3–7 there are 2–14 cells. The latter have the appearance of small ganglia and lie on the aliform muscles where the transverse nerve divides to innervate the individual muscle fibres. All of the peripheral neurosecretory cells appear to produce the same secretion, some of which is discharged through the transverse nerves and released at the proximal neurohaemal dilations. Other fibers extend distad from the cell bodies and may supply the aliform muscles.

The major ganglion in the pelvic plexus of the male rat: a histochemical and ultrastructural study.

To further evaluate the role of autonomic ganglia in the regulation of pelvic visceral activity, the neural elements in the major pelvic ganglion of the male rat have been studied with histochemixal and electron microscopic techniques. The principal findings are that the ganglion is composed of cholinergic and adrenergic ganglion cells as well as small intensely fluorescent (SIF) cells. Polarity in the ganglion is indicated by clustering of small ganglion cells which stain intensely for acetylcholinesterase (AChE) along the pelvic nerve while larger cells, with weak to moderate AChE activity, collect near small branches of the hypogatrric nerve. Some cholinergic ganglion cells are enclosed by a plexus of adrenergic terminals. SIF cells appear to be in contact with both cholinergic and adrenergic cells, although many of the fluorescent beads around adrenergic neurons may be short dendrites of ganglion cells, rather than processes of SIF cells. Two types of SIF cells may be distingiosjed on the basis of size and morphology of their granulated vesicles. Afferent synapses of the cholinergic type were common on SIF cells of the large granule and small granule type. Portions of SIF cells with large granules occur within the capsule of ganglion cells. Contacts seen here were interpreted as efferent synapses from SIF cells to the dendrites of ganglion cells.

The role of carboxylic groups in the depolarizing action of some bisquaternary ammonium compounds and their derivatives on the neurons of the gastropod mollusc Limnaea stagnalis

Abstract 1. The depolarizing potency of the following three homological series: ‘BTM’: Me 3 N (CH 2 ) n NMe 3 , n = 9–16; ‘D’: Me 3 N CH 2 CH 2 O CO (CH 2 ) m CO O CH 2 CH 2 NMe 3 , m = 1–8; ‘D-mono’: Me 3 N CH 2 CH 2 O CO (CH 2 ) m CO O CH 2 CH 2 H, m = 2–8, was compared by means of intracellular microelectrodes on identified giant neurons of the small parietal ganglion of Limnaea stagnalis after irreversible inhibition of cholinesterases. The equipotent molar ratio of the corresponding members of the series D : D-mono : BTM was approximately 1 : 3 : 10. 2. These results indicate the important role of the ester groups in the depolarizing action of the quaternary and bisquaternary compounds as well as the importance of the second cationic head in series D. 3. At variance with all other members of the D-series, suxamethonium (D-2) is not more active than decamethonium (BTM-10) and less potent than D-2-mono. The second cationic head reduces the depolarizing action of suxamethonium on the neurons studied. 4. The study of some derivatives of the D-mono series had shown that replacing of the ‘second’ (more remote from the nitrogen) ester group by two methylene groups strongly reduces the depolarizing activity but the ‘reversal’ of the second ester group (that is the transposition of the ether oxygen and the carbonyl group) does not change the activity. 5. The contribution of the second ester group in the interaction of the members of the D-mono series with the cholinoceptive membrane is discussed.

Properties of sustained and transient ganglion cells in the cat retina.

1. The functional basis for a sustained/transient classification of cat retinal ganglion cells has been strengthened by quantitative measurements of the sizes of the centre and surround components of receptive fields. Transient cells had larger surrounds than sustained; the distributions were non-overlapping. Although the distributions of centre sizes overlapped, the transient cells had very significantly larger centres on average.2. There were characteristic differences in area-threshold and annulus-threshold curves and shapes of responses to brief and long flashes of light, and relative differences in the nature of surround adaptation and maintained discharge rates.3. The distinction of sustained from transient units survived over a wide range of backgrounds including the two principle reorganizations of function: relative weakening of surround components at low background; Purkinje shift at high.4. Sustained and transient units were differentially distributed in the retina: there was an overwhelming preponderance of sustained units in the area centralis.5. It is proposed that the transient units are the so-called multidendritedeep cells and the sustained units are the variously styled small ganglion cells.

Comparative and topographical anatomy of the fowl. LXIV. Sympathetic nervous system of the fowl. 3. Plexus celiacus and plexus mesentericus cranialis

Tlae gross anatomy of connections and distributions of llexus celiacus and Plexusmesentericus cranialis, and their relations to the splanchnic nerves in the fowl weredescribed and illustrated in detail on the basis of studies on 26 cases of macroscopicaldissection. Discussion was made at full length on the nomenclatures appearing in litera-ture and on tltose adopting in the present paper. The results obtained are shown inTable I. l-lae following findings warrant emphasis.The thoracic sympathetic nervous system is generally represented by seven pairs of ganglia and two trunks, Rami interganglionares and Rami interganglionares accessorii.The Nn. splanchnici majores arise from tlte second to tlxe fifth tltoracic ganglia and rundownward to the turning point of tlte celiac artery derived from the abdominal aorta(Table 2). They form some small ganglia, Ganglia celiaca, there. Nerves originated fromtlaese ganglia, collectively called the Plexus celiacus, are accompanied by the celiac artery.The plexus receives some anastomosing branches, collectively called the Plexus celiacusaccessorius, from Ganglia suprarenalia cranialia and Plexus mesentericus cranialis at eachlevel of the turning point of the right glandular gastric artery and the distal point ofthe caudal splenic artery. The Plexus celiacus extends along the branches of the celiacartery to form Plexus gastrici, Plexus lienalis, Plexus hepaticus, and Plexus pancreati-coduodenalis. The N. intestinalis anastomoses with the Plexus pancreaticoduodenalisnear the opening of the pancreatic duct.The N. vagus anastomoses with the Plexus gastrici at an intermediate level betweenthe glandular and the muscular stomach. Some peripheral branches of the N. vagussupply the liver along the left hepatic artery, while they are distributed in the muscularstomach. A part of the Plexus celiacus extends to the ileum and cecum along the cranialileocecal artery.Nerves from the fifth to the seventh thoracic ganglia and from the first lumbosacralganglion form the Nn. splanchnici minores (Table 2). These, nerves gather togetheraround the adrenal and form the Ganglia suprarenalia cranialia and caudalia. There areanastomosing branches between the Nn. splanchnici majores and minores. The Plexusceliacus accessorius arises from the Ganglia suprarenalia cranialia. Some nerves originatedfrom the Ganglia suprarenalia caudalia become the Plexus aorticus around the abdominalaorta. Other nerves from these ganglia form other ganglia; that is, the Ganglia mesentericacranialia located on the lateral surface of the caudal vena cava. The Plexus mesenteric

Patterned activity of the buccal ganglion of the nudibranch mollusc Archidoris pseudoargus.

Patterned activity of the buccal ganglion of the nudibranch mollusc Archidoris pseudoargus.

Observations on the phrenic nerves and the ductus venosus in human embryos and fetuses

The phrenic nerves, celiac plexus, and portions of the vagus nerves were studied in human embryos and fetuses which had been sectioned serially and stained with silver. The phrenic nerve gives off a branch to the plexus of nerves along the internal thoracic (mammary) artery. In some instances, a small ganglion was observed in the path of the phrenic nerve in the neck. In the root of the neck, communicating branches from the sympathetic trunk and ganglia were seen to join the phrenic nerves. Nerve bundles are described which pass between the celiac plexus and branches of the phrenic nerves in the diaphragm. Routes for fibers to pass from these nerves in the diaphragm to the sphincter of the ductus venosus are also described, as well as a route for nerve fibers from the vagal trunks to this sphincter. The significance of these findings is discussed.

Ultrastructural and acetylcholinesterase studies on the innervation of the ductus arteriosus, pulmonary trunk and aorta of the fetal lamb

Ultrastructural and acetylcholinesterase (AChE) studies have revealed that the media of the fetal lamb ductus arteriosus, pulmonary trunk, and aorta are composed of alternate layers of concentrically arranged smooth muscle cells and connective tissue elements. The connective tissue layers composed mainly of collagen and elastica also contain blood vessels, leukocytes and mast cells and are looser than that present in adult elastic vessels. “Close contacts” are present between muscle cells in the same and some adjacent layers and are considered to provide a pathway for the spread of impulses between muscle cells. Large bundles of AChE-positive nerve fibers and small ganglia were seen in the adventitia. Smaller nerve bundles were seen extending into the outer third of the media where they were present in both the muscle and connective tissue lamellae. Nerve fibers were separated from muscle cells by a distance of from 2 μ to 75 A. On the basis of their intra-axonal vesicles, especially the small granular vesicles (600–800 A) and their AChE activity it seems likely that both adrenergic and cholinergic nerves are present in these vessels.

Distribution and Ultrastructure of Epidermal Sensory Cells in the Freshwater Snails Lymnaea Stagnalis and Biomphalaria Pfeifferi

The epidermal receptor cells and their distribution throughout the body surface of Lymnaea stagnalis and Biomphalaria pfeifferi were studied by means of light and electron microscopic techniques. The investigations reveal general agreement between the two species. The receptor cells are primary sensory nerve cells with the cell bodies lying below the epidermis. The subepithelial cell bodies are frequently grouped together forming small ganglia, particularly in rich sensory regions, such as the lips and the tentacles. Dendrites extend from these sensory cell bodies between the epidermal cells and form free nerve endings at the surface of the epidermis. Six different types of free nerve endings are distinguished on the basis of the number of cilia present and on the length and structure of the cilia roots. A survey of the distribution of the sensory cells revealed that they are restricted primarily to the tentacles, lips, front edge of the foot, pneumostome and mantle edge, although they are also present in the dorsal and lateral surface of the foot. No free nerve endings were found in the dorsal head epidermis. Only one type of nerve ending was found to have a specific localization, whereas the other types have a general distribution. Although it is difficult to determine the function of the different types of free nerve endings in an ultrastructural study, some suggestions are made on the basis of morphological comparisons with receptor cells in other species and also on the basis of behavioral and physiological experiments which have been performed on L. stagnalis.

II. Drosophila neuron differentiation in vitro.

Many investigators have described the growth of axons in vitro from explants of embryonic mammalian or bird tissue (Murray, 1965). In all cases the explant contained cells from already differentiated nervous tissue and no claims were made for neuron differentiation from stem cells. Niu and Twitty (1953) and Barth and Barth (1958) observed the development in vitro of long processes which presumably were axons, from neurons that had differentiated from fragments of amphibian gastrula ectoderm. Neuroblasts in explants taken from grasshopper embryos show repeated divisions in vitro (reviewed by Carlson and Gaulden, 1964). The cytoplasm is distributed unequally at each division to generate a small ganglion cell and a large cell that will divide again. Each neuroblast thus serves as a stem cell for several ganglion cells but no axons are produced in vitro.

Tumors of the skin

Tumors of the Skin i s based on a presentation mode by Herbert Conway, MD, at the 118th Annuol American Medical Assaciotion Convention, NY. Dr. Conway died Aug 25, 1969 from the last in a succession of coronary thromboses. His ossocbtes, Randolph Guthrie, MD, Dicran Goulian, Jr., MD, and Jomes W. Smith, MD, completed this paper, which he hod begun for publication in the AORN Joornol. A fellow in the American College of Surgeons, Dr. Conway's last positions were at the New York Hospital, as attending surgeon in charge of plastic surgery, and ot Cornell University Medical College as clinical professor of surgery. He received bachelors, masters and doctoral degrees from the University of Cincinnati, and had memberships in the M A , the American Association of Plastic and Reconstructive Surgeons, the American Board of Plastic Surgery, and in over 30 other professional arganizotions. Dr. Conway served in numerous official positions in the profession, lectured and instructed throughout the world, and filled editorial positions in many classified as benign, and is it causing any symptoms or cosmetic deformity? If the tumor is benign, such as a small ganglion, and is not symptomatic or unsightly, then it can be left alone and observed. If, on the other hand, the benignity of the tumor is at all in doubt or it is symptomatic or cosmetically undesirable, it must be removed. The common

The innervation of the umbilical vein in human embryos and fetuses.

AbstractIn human embryos and fetuses, a small bundle of nerve fibers from the anterior and posterior vagal trunks descends between the layers of the hepatogastric ligament. These fibers pass to the region of the junction of the umbilical vein with the ductus venosus. At this junction, there is a slight thickening of the muscular wall. Nerve fibers pass to this junction and the proximal portion of the umbilical vein.Fibers from the posterior vagal trunk follow the left gastric artery to the celiac plexus. Fibers from this plexus follow the hepatic artery into the lesser omentum and along the portal vein to the liver. Continuing along the left branch of the portal vein, fibers reach the proximal portion of the umbilical vein and its junction with the ductus venosus.Ganglion cells were observed along the course of vagus nerve fibers to the umbilical vein. In embryos these cells were observed on the lower end of the anterior vagal trunk near the attachment of the upper end of the lesser omentum to the lower end of the esophagus. In older fetuses they were found in a small ganglion in the connective tissue surrouding the distal end of the ductus venosus.

The origin and the course of the communicating branch of the facial nerve to the lesser petrosal nerve in man.

AbstractIn order to clarify the origin and the course of the communicating branch, 25 human nerve complexes (entire intra‐osseous part of the facial nerve, greater petrosal nerve, lesser petrosal nerve, communicating branch, auricular branch of the vagus) and stapedius muscles were dissected out and removed as a whole. Each of the 25 complexes was dehydrated, sectioned serially at 10–20 μ, and either stained with Luxol Fast Blue or treated with a silver technique. The communicating branch was observed to originate from the auricular branch of the vagus. It ascended first along the anterior side of the third intra‐osseous part of the facial nerve and then penetrated the stapedius. From within the stapedius some of its fibers continued anteriorly as a nerve bundle through the facial sheath of the second intra‐osseous part of the nerve. This nerve bundle separated from the seventh nerve upon approaching the geniculate ganglion, and joined the lesser petrosal nerve. The communicating branch consisted mainly of small myelinated fibers in the course of which either isolated ganglion cells or small ganglia were sometimes present.

Adrenergic Nerves in the Avian Eye and Ciliary Ganglion

The distribution of adrenergic fibres to the eye and to the ciliary ganglion was studied in pigeons, chicken and ducks with the aid of the sensitive and highly specific fluorescence method of Falck and Hillarp. In some animals the intensity of the fluorescence was increased by treating the animals with Nialamide and 1-DOPA. The cornea contained no adrenergic fibres except at the limbus, where a plexus of adrenergic varicose fibres was seen, partly associated with vessels. In the chamber angle, adrenergic varicose fibres were common in the loose connective tissue covering the canal of Schlemm. The canal of Schlemm was supplied by only few adrenergic fibres, but such fibres appeared along the intrascleral aqueous drainage vessels. In the iris, adrenergic varicose fibres appeared immediately in front of the posterior layer of pigment cells, strongly indicating the presence of a dilator homologous with that seen in mammals. The frontal third of the stroma contained several adrenergic varicose fibres, many of which seemed to lack association with any vessel. Varicose adrenergic fibres were also sparsely seen in the striated muscle of the iris. The ciliary processes contained many adrenergic varicose fibres, at least part of which seemed to be associated with the ciliary epithelium. The striated muscles of the ciliary body contained adrenergic varicose fibres along the vessels only. The retina contained adrenergic varicose fibres in three layers in the inner plexiform layer. Adrenergic ganglion cells of two sizes were detected in the inner nuclear layer. The retinal vessels had no adrenergic nerve fibres. The pecten was also devoid of adrenergic nerve fibres, except along the vessels close to the papilla. The optic nerve contained adrenergic varicose nerve fibres along vessels only. In the ciliary ganglion, varicose adrenergic fibres appeared at the small ganglion cells, often forming baskets of synaptic character.

The neurological basis of learning.

THE NEUROLOGICAL BASIS OF LEARNING SIR JOHN GADDUM* I.Introduction Anyone who is interested in the activities of individual neurons in the cerebrum would like to form some picture of their relation to the activities ofthe whole animal. Much work has been done on this topic and everyone must make his own summary and consider the meaning ofthe facts. The speculations given below are an attempt to do this. They are mostly either unoriginal or improbable, but it is possible that one or more may provide the stimulus for further experiment. II.Brain Models The biological success ofanimals depends partly on their power to make movements and to adapt these movements in the light ofsignals coming from the outside world. When the conditions are standardized it is possible to get a constant response to a given signal. This fact led in the nineteenth century to the belief that a reflex was a mechanical response which did not depend on the previous history ofthe animal. There is, of course, some truth in this belief, but it is surprising what simple nerve nets can learn from experience. Bees can learn that a blue background is associated with food [i]. They can also learn the way to food and to communicate this information to other bees using the sun as a guide—and the weight oftheir brain is only about 2.5 mg. Octopus vulgaris can learn that some white shapes are signals of danger and will then take appropriate avoiding action [2]. The flatworm (planarian) Dugesia dorotocephala was shown [3] to be able to learn * Institute ofAnimal Physiology, Babraham, Cambridge, England. Present address: io Fendon Close, Cambridge, England. 436 SirJohn Gaddttm · Neurological Basis ofLearning Perspectives in Biology and Medicine · Summer 1963 that a bright light was a signal for an electric shock, which made it contract its whole body. Later work showed that these animals could learn to be guided by light through a simple Y-maze, and led to other surprising discoveries, which are not directly relevant to the present discussion . These animals are less than 2 cm. long, and their nervous system consists of two small ganglia, one of which is directly concerned with learning. These facts show that learning may occur in a small organ. Similar learning also occurs in a wide variety ofother simple animals [4]. It is tempting to suppose that the mechanism which controls behavior and modifies it in the light ofexperience has something in common in all animals. The word "plastic" is applied to nerve nets whose properties are altered by experience, and it is thought that the study ofplastic nerve nets in simple animals may throw some light on the mode of action of the brains ofcomplex animals. The main seat ofthe intellect must be a plastic nerve net of some kind, though it is possible to have plasticity without intellect. In the higher mammals, intelligence is associated with the cerebral cortex since: (1) the species ofanimal with the most complicated cortex are in general the most intelligent; (2) when the cortex is absent through disease, intelligence is absent too; and (3) extirpation ofthe whole cortex destroys intelligence. It does not follow, however, that the cerebral cortex is the only part of the brain where plastic changes occur. Most nerve nets are to some extent plastic and the difference between them is a matter ofdegree. According to Gastaut and others [5], the thalamus and the reticular formation play a major part in the formation ofconditioned reflexes. There has been much speculation about how plastic nerve nets work, and various theories have been suggested in the form ofmodels which are thought to resemble real brains. In the early part ofthis century the brain was thought to be like a telephone exchange, each sensation being switched through to oneparticular center and each motoractcaused byanother particular center. The function of the brain was to connect these two centers with one another in some unknown way. This theory was taken to imply that each sensation, andeach motor act, depended on a localized area ofthe brain and would disappear ifthat area was destroyed. This is true in the sense that visual sensations are analyzed in the occipital cortex and...

THE NEUROENDOCRINE SYSTEM AND STOMATOGASTRIC NERVOUS SYSTEM OF THE ADULT TSETSE FLY GLOSSINA MORSITANS

The brain of Glossina morsitans Westwood contains four groups of neurosecretory cells which are stainable with chrome haematozylin and phloxin. The axons of these cells form a pair of nervi corporis cardiaci which pass posteriorly from the brain and innervate the corpora cardiaca and corpus allatum before uniting with a small ganglion posterior to the corpora cardiaca. This ganglion is considered to represent the fusion of the fusion of the hypocerebral and ventricular ganglia which remain separate in other insects.There is no frontal ganglion in the adult Glossina and the recurrent nerve fuses with one of the nervi corporis cardiaci immediately behind the brain. The oesophageal nerves arising from the fused hypocerebral and ventricular ganglia innervate the oesophagus in the anterior part of the thorax, the proventriculus and the posterior extension of the oesophagus close to the crop. These nerves possess both sensory and motor nerve endings. The differences which exist between Glossina and other cyclorrhaphous Diptera with respect to their neuroendocrine/stomatogastric system are noted and considered in terms of the control of neuroendocrine function.

Terminal innervation of the uterus and vagina of the domestic hen.

Summary. The distribution of nervous tissue within the oviduct of the hen has been examined with particular reference to the isthmus, uterus and vagina. The uterus and utero-vaginal junction were well innervated and nerve cells were more abundant in these regions. An extensive mesh of large nerve fibres was evident in the uterus, together with a much finer network of mainly single fibres associated with the muscle cells. Fewer large nerves were found in the utero-vaginal and vaginal regions. Many of the nerves in the isthmus innervated the blood vessels. Several small ganglia were found externally, towards the caudal end of the uterus and surrounding the uterovaginal junction. The arrangement of the smooth muscle layers of the posterior oviduct is described.

The anatomy of the nervous system in the genus Gerris (Hemiptera-Heteroptera)

The most successful methods used in this study were Palmgren’s silver-on-the-slide technique, the rapid silver nitrate method of Golgi, and a method that has seldom been applied to insect material, the Golgi-Cox mercuric chloride method. A way of preparing sections of adult hardened insects by infiltrating with wax prior to softening with chlorinated acetic acid and nitric acid was also employed. The nervous system of Gerris shows a high degree of condensation in that all the segmental neuromeres are fused. This characteristic of the nervous system may be associated with the disposition of the one hundred and twenty-two pairs of muscles. The nerves of the head are specialized in association with the complex mouthparts. There are distinct stylet and labral ganglia, and peripheral interconnexions between some of the nerves. The posterior labral nerve was traced to the principal salivary gland. The reticulum described by Baptist (1941) as of a nervous nature was shown to consist of fine muscle fibres: the much finer nerve fibres were also stained in silver preparations. The many separate nerves of the prothorax reflect the unspecialized nature of this segment as compared with the meso- and metathorax in which most of the fibres are gathered into a few nerve trunks. The coalesced neuromeres of the abdominal region give rise to a pair of posterior nerve trunks connected with small ganglia or lateral bodies lying near the spiracles. These ganglia appear similar to the structures described by Landois & Thelen (1867), as controlling spiracular movements in Cossus . Rough estimates of the number of cells in different parts of the nervous system were correlated with the percentage success of staining methods, and specialization of the neuromeres. The form and arrangement of neurones within the optic and protocerebral centres of Gerris conforms for the most part to the patterns worked out in other insects, though there do not seem to be as many different types of internuncial neurone in the optic lobes of Gerris as exist in Apis or Calliphora (Cajal & Sanchez 1915). The corpora pedunculata are connected through a dorsal glomerulus with the deutocerebrum, the glomerulus having the form of a loose meshwork of fine fibres rather than of a distinct calyx. The deutocerebrum is indistinctly divided into anterior and posterior glomeruli, as described in Apis by Sanchez (1936). The form and size of the elements composing the somewhat enigmatic posterior glomerulus in Gerris supports the view that this is a motor centre. The close association between the maxillary and mandibular nerves is to some extent reflected in the internal organization of these neuromeres. Separate ventral areas could be distinguished, but ganglionic boundaries were indistinct. The large labral centre shows many of the features of a trunk ganglion. The pattern of neurones in the thoracic and abdominal centres could be compared in detail with the pattern described by Zawarzin (1924) in the larva of Aeschna . There are three unusually large internuncials with processes in this region, and cell bodies in the protocerebrum and suboesophageal centres. It is suggested that they form part of a dual physiological system controlling the motor centres of the thorax (Roeder 1953). The mesothoracic centre was made a special object of study as representative of the thoracic neuromeres. The fibre tracts are clearly marked and can be seen to correspond to functional regions within the centre. The alary nervous system of the mesothorax was investigated in some detail in both winged and wingless forms of Gerris . In the flying forms dorsal and ventral tracts can be distinguished, associated with motor and sensory regions of the mesothoracic neuropile respectively. In forms without wing muscles or fully developed wings the dorsal tract is absent or vestigial and the ventral tract is clearly reduced. The abdominal neuromeres are very closely compacted so that they tend to lose their identity. The ventral longitudinal tracts are unusually well developed and this may be correlated with the importance of the sensory areas.

Histological Studies on the Innervation of the Esophagus in Formosan Macaque

In the esophagus of Formosan macaque, no esophageal glands could be found existing. The tunica muscularis is striated nature in the upper part of the esophagus but comes to be replaced by smooth musculature in the lower part, and in the lowermost 1/6, the muscularis entirely consists of sheer smooth musculature.The nerve fibres coming into the esophagus form the periesophageal plexus provided with small ganglia in its adventitia.AUERBACH's plexus in the upper part of the esophagus of this animal is very ill developed, but in the mid-part and below it considerably gains development. The ganglion cells forming the ganglia in the plexus were found to be of DOGIEL's Type I and of apolar or infantile type, no DOGIEL's Type II cells being ever found. The ganglia of MEISSNER's plexus are better developed in the upper than in the lower part of the esophagus and contain cells usually of infantile type but sometimes of DOGIEL's Type I.The vegetative fibres distributed in the esophagus comprise very fine sympathetic fibres and somewhat thicker parasympathetic fibres, and forming terminal reticula (STOHR) as their terminations, come into control by contact over the tissue cells supplied, as in the case with man and the other animals studied hitherto.The motor fibres supplied to the striated muscle tissue of the esophagus of the Formosan macaque end either in grape-like terminations prevalent in the human esophagus or quite as often in motor end-plates that are in predominance in the caprine esophagus. From this we may infer that the macaque stands just mid-ways between man and goat in this respect.The sensory fibres supplied to the esophagus of the macaque consist in thicker fibres than motor fibres and form their terminations in all the layers of the esophagus.In the tunica muscularis are found unbranched and simple branched sensory terminations, particulary often in the intermuscular connective tissue septa. Their fibres usually are smooth surfaced thick ones frequently changing size and show more or less conspicuous glomerular arrangement. Their terminal areas contain a few specific cell nuclei. Branched terminations composed of terminal fibres showing no looping in their courses, however, were not rare either. Besides some branched terminations are formed by side branches sent out from the stem fibres into the tunica muscularis in their courses toward the submucosa. It is of deep interest that branched terminations ending after running winding courses specific to sensory fibres are found in the striated muscle tissue in the upper esophagus.Rather complex branched terminations are found in the ganglia of AUERBACH's as well as MEISSNER's plexus. In these, the many branch fibres show conspicuous change in size, run looped courses and spread out over rather large areas, ending in blunt or sharp points. It is of special interest that terminations in glomerular arrangement are not rare, either.Unbranched and simple branched sensory terminations of fibres running conspicuous snake-like courses are found in the submucosa.Unbranched and simple branched terminations were found in the lamina propria mucosae, too, but here the courses of the terminal fibres are not very wavy, the fibres ending in sharp points just beneath the epithelium. No intraepithelial fibres were ever found in the esophagus of the monkey.The sensory terminations formed in the esophageal wall of the Formosan macaque described above are inferior in structure to those in man, but generally superior to those in dog, goat and snapping turtle.