Perisympathetic Organs Research Articles

Comparative immunocytochemical study of release sites of insulin, glucagon and AKH-like products in Locusta migratoria, Periplaneta americana, and Carausius morosus

Insulin, glucagon and adipokinetic hormone antisera were applied to the corpora cardiaca, perisympathetic organs, neurohemal areas and peripheral neurosecretory cells of three insect species, the locust Locusta migratoria, the cockroach Periplaneta americana, and the stick insect Carausius morosus. The neurohemal part of the corpora cardiaca was shown to be immunoreactive to both insulin and glucagon antisera while the glandular cells reacted to adipokinetic hormone antisera. The perisympathetic organs seem to be devoid of these three substances, but certain peripheral neurohemal areas contained AKH and glucagon immunoreactive products. The latter were found to originate in the peripheral neurosecretory cells.

Diversity of neurohormonal release sites in insects: Coexistence of two different (α and β) types of neurohemal structure in the perisympathetic organs

A comparative ultrastructural study of insects was made whose primitive perisympathetic organs consisted either of a single median neurohemal formation per segment ( Periplaneta americana) or of two transverse formations ( Carausius morosus), or again, of three—one median and two transverse—as in Locusta migratoria. The results showed that the perisympathetic organs always comprised two types of structure (α and β), even when a single formation exists. In Periplaneta and Carausius, both types were seen to coexist in the same neurohemal formation. In Locusta, however, they were separated, the α structure constituting the median organ and the β structure, the two transverse organs. Each of the two structures have special features: the β structure displays the usual characteristics of a loose neurohemal organ, i.e., it is penetrated by sinuses and has neurosecretory endings devoid of a glial coat; the α structure, on the contrary, forms dense compact organs whose endings are covered with a continous glial layer. During the evolution, this last structure gradually separated from the other neurohemal formations. It was observed to correspond to a single type of neurosecretory cell, distinct from all other cell types by the particular mode of its release. These results for primitive perisympathetic organs confirm earlier findings for advanced organs. They indicate that both the α and β structures are generally present in insects, thus showing their importance in the physiology of these animals.

Experimental and ultrastructural study of the control of ovulation and parturition in the tsetse fly Glossina fuscipes (Diptera)

Injections of haemolymph, organ extracts and various other substances, as well as in vitro experiments, show that ovary and oviduct extracts on the one hand, and dibutyryl cyclic AMP on the other, enhance ovulation, whereas parturition is stimulated by extracts of the brain, thoracic ganglionic mass, nerve XVII, different parts of the genital apparatus and perhaps proctolin. On the contrary, the proximal neurohaemal organs (corpus cardiacum and perisympathetic organs) appear to contain a substance inhibiting parturition. Lastly, normal intact flies cannot respond to extracts facilitating parturition in decapitated flies. Neuromuscular junctions probably containing peptides and neurotransmitters are described in the muscles of the ovaries, oviducts and the vaginal aperture. Other junctions containing neurotransmitters only are present in uterine and intersegmental muscles. The neurohaemal areas of nerve XVII contain 3 types of peptidergic terminals. From our overall results it is concluded that ovulation is regulated by neurosecretory products released at neuromuscular junctions in the ovaries and oviducts. Parturition control is more complicated. A first neurohormone (parturition-stimulating hormone) appears to be produced in the nerve centres and released in neurohaemal areas located on nerve XVII in the vicinity of the uterus; it enhances the contraction of this organ. A second neurohormone, the parturition-inhibiting hormone may be released in the corpora cardiaca and the median perisympathetic organ. A cephalic nervous factor might exert inhibitory action.

Ultrastructure of two opposite types of abdominal perisympathetic organs in the heteropteran, Roscius elongatus Stål (pyrrhocoridae). abundant release of neurosecretory product by intraganglionic organs

The ultrastructural study of perisympathetic organs (POs) in Roscius elongatus revealed the existence of two opposite neurohemal structures. Distal POs formed a network at the end of each of the first pro-, meso-, metathoracic, and abdominal nerves. They display a thin branched structure favoring contact between axon endings and hemolymph. The distal metathoracic POs contained two types of neurosecretory ending, and the distal abdominal POs three types. On the contrary, “subjacent” POs, strangely located laterally in the abdominal area of the ganglionic nerve mass, display a dense compact structure, containing only one type of neurosecretory ending. These characters demonstrate that the “subjacent” POs, earlier classified as transverse POs because they are symmetrically located, are in fact median POs. In transverse POs, signs of extrusion by exocytosis were observed only in one type of neurosecretory ending. In “subjacent” POs unusual pictures were found indicating abundant release by single or compound exocytosis. Such pictures prove that “subjacent” POs have a neurohemal function despite their dense structure and internal localization. Physiological implications of these opposite structures are discussed.

Ultrastructural comparison of the perisympathetic organs in three Coleoptera: Chrysocarabus auronitens F., Oryctes rhinoceros L. and Tenebrio molitor L

Ultrastructural comparison of different types of perisympathetic organs (POs) in three species of Coleoptera ( Chrysocarabus auronitens, Oryctes rhinoceros, and Tenebrio molitor) showed that the structure of these organs was not related to their morphological types but to their topography. Two kinds of PO structure may be distinguished: compact median and diffuse lateral. They were similar in that both were surrounded by thin neural lamellae and exhibited numerous glial cells originating in the perineurium (type I perineurial cells) as well as abundant neurosecretory endings. They were different in as much as in median POs, the neurosecretory endings were generally surrounded by perineurial processes but in transverse POs, these endings were sheathless. Only one type of neurosecretory axon was distinguished in the median organs but three or four in the transverse. The nature of the processes by which neurosecretory granules are released may depend on the type of neurosecretory axon. For instance, exocytosis always occurred for dense spherical granules, and granule fragmentation was visualized for granules of smaller size.

The abdominal perisympathetic neurohemal organs of the cockroach Periplaneta americana: innervation revealed by cobalt chloride diffusion.

By retrogradely diffusing Co2+ through the two perisympathetic organs associated with the transverse nerve of the third abdominal ganglion and subsequently precipitating the sulfide, four groups of neuron somata in that ganglion and two somata in the second abdominal ganglion are revealed. The four groups in the third abdominal ganglion occur at various levels adjacent to the midsaggital plane, and there are 8 to 16 neurons in each group. Comparable numbers of putative neurosecretory cells, with granules that are paraldehyde fuchsin and azocarmine positive, are located in most of these regions. Axons containing granules with these staining characteristics are also present in the perisympathetic organs. It is suggested that the granules are secretory products of the median neurons. The locations of the cell bodies, their sizes, and some of the intraganglionic pathways of their processes are described.

Les organes perisympathiques des dipteres

This paper describes the perisympathetic organs (PO) of 8 families of Diptera, inc. Culicidae, Tabanidae and Muscidae which, between them, represent the principal subdivisions of the order. In general, the PO of these insects do not form large obvious structures and so they are not easily localized. Histologically, however their structure is classically that of neurohaemal organs. The thoracic PO differ from those found in the abdomen. In the thorax, PO associated with the fused ganglia are of the evolved type, while in the abdomen where the nervous system is not concentrated, the PO are of the primitive type. In Glossina, where the abdominal ganglia fuse with those of the thorax to form a single thoraco-abdominal ganglionic centre, there is a peculiar median abdominal PO. It consists of neurosecretory endings located between the glial cells of the perineurium, in the postero-dorsal part of the ganglionic centre. It seems that it comes from metameric internal organs which have lost their connective tissue boundaries. This unusual arrangement probably reflects the extreme degree to which the nervous system is concentrated in this insect. In several of the species studied, peripheral neurones were found lying close to the neurohaemal areas. Their function is discussed.

Rôle des organes perisympathiques et dynamique de la secretion de la bursicon chez Tenebrio molitor

Light and electron microscope observations have been made on the perisympathetic organs (P.O.) situated on the dorsal somatic abdominal nerves in pupae of Tenebrio molitor. Tests carried out with extracts of P.O. using a bioassay method on pupae of Tenebrio at various developmental stages indicate that these organs have an important role in the storage and release of the tanning hormone, bursicon. The P.O. extracts from the abdominal segments (2 to 5) of 5-day-old pupae were found effective but not those from pharate adult (2 days before ecdysis). The storage and release of bursicon occur later from the P.O. of the posterior abdominal segments (6 to 8). The activity of the blood begins to be effective in the pharate adult 2 days before ecdysis, reaches a maximum 1 hr after the adult ecdysis, and decreases thereafter. This study carried out on the various parts of the nervous system shows that all these parts are effective at a certain stage of the pupal and adult development following an antero-posterior gradient. In the cephalic region, this activity is early and long-lasting, but it appears at later stages and only for a short time in the thorax and abdomen. This phenomenon indicates that bursicon is either passed along the ventral nervous chain or it is synthesized in different parts of the nervous system at successive developmental stages. In the present paper, we have tried to give a comprehensive summary of the dynamics of bursicon in insects.

Le rôle du système nerveux central sur les mécanismes de l'oviposition chez Carausius morosus et Clitumnus extradentatus

Cephalic nervous connexions were found necessary for oviposition and normal egg maturation in the two species studied. Neurosecretory cells of A type from the brain, suboesophageal, thoracic, and four abdominal ganglia seem to elaborate a stimulating substance for egg laying. This neurosecretion type is not present in corpora cardiaca, corpora allata, the four last abdominal ganglia, or perisympathetic organs which have no clear-cut effect on oviposition. The circadian rhythm of egg laying appears to be entirely controlled by the liberation of this neurosecretion and by an inhibitory factor localized in the head. In Carausius, egg deposition by the valvulae of the ovipositor is regulated by these two factors whereas egg transit through the common oviduct is a distinct preliminary step under nervous control. This nervous effect from the posterior region does not exist in Clitumnus.

Les Organes Périsympathiques des Insectes Holométaboles: I. Coléoptères

SummaryA. Provansal & J. P. Grillot: Perisympathetic Organs in the Holometabola Insects. I. — Coleoptera.The metamerie neurohaemal organs otherwise called the perisympathetic organs (P. O.), associated with the sympathetic nervous system of the ventral nerve chain, have been described in 24 species representing the principal groups of Coleoptera.The location of the P.O. is much more variable in the Coleoptera than in Polyneopteran Insects. This variability is associated with the condensation of the ventral nerve chain and the individualization of the sympathetic nervous system. When there is an advanced fusion of neuromeres, the P.O. may be located internally under the ganglionnic neurolemma. The P.O. are sometimes located around the somatic nerves if there is a condensation in the sympathetic nerves. A double location of the P.O. is noticed along the median nerves and the somatic nerves as in the Hymenoptera.The structure of these organs is very similar to that of classical neurohaemal organs. The neurosecretory products are generally of the type « C », rarely of the type « A ». The neurosecretory neurons have been found in several species of Coleoptera contrary to the observations in the Polyneopteran Insects.First experiences show that the P.O. play a possible role in the release of the tanning factor.