Studies on the hexapod nervous system. III. Histology and histochemistry of cockroach neuroglia

Abstract

A growing interest in the neuroglial elements of the vertebrate nervous system is evidenced by a steadily accumulating literature, and by the appearance of two recent monographs (Glees, '55; Windle, '58). These efforts are justified by the supposition that neuroglia and its equivalent in the peripheral nervous system (satellite and Schwann cells) execute a role in the economy of nervous tissue which is considerably more dynamic than that of mechanical support. Thus, these non-nervous elements are presumed to participate in the formation and maintenance of myelin, in nerve regeneration, in the functioning of the blood-brain barrier, and probably in electrophysiological phenomena related to nervous activity.Relatively little is known about the structure of invertebrate neuroglia; still less about its histochemistry. As a consequence those unifying concepts so frequently provided by the comparative approach are lacking. An understanding of the structure of invertebrate neuroglia is also important in its own right, constituting a prerequisite to investigations of its functional significance. The present study on certain features of insect glia is a contribution toward this end. MATERIALS AND METHODSThe majority of observations were made on the nervous systems of adults of the cockroaches Periplaneta americana (L.) and Leucophaea maderae Fab. First instar nymphs of these two species, as well as adults of the milkweed bug, OncopeZtus fasciatus (Dallas), and the Bermuda land crab, Gecarcinus lateralis (F.), were examined in order to clarify certain points. The animals were usually killed and fixed as described previously (Pipa et al., '59). Alcoholic Bouin's, aqueous Bouin's, Lillie's acetic-alcohol-formalin (AAF; Lillie, '54) , Regaud's followed by postchromation, Helly's, and 10% formalin were the fixatives most commonly employed. With few exceptions the nerve cords were dehydrated with normal butyl alcohol, vacuum infiltrated with tissuemat (60-63°C) and sectioned at 5-7 p.Histological staining techniques Histological features were revealed by examining the preparations stained with cresyl violet (pH 3.5); toluidine blue (Lillie, '54); Mallory's triple stain; Gomori's aldehyde-fuchsin following the procedure of Halmi ('52); Gomori's chrome alumhematoxylin (GCAH; Gomori, '41) ; muver and Barrera's copper phthalocyanin method (CPM; Pearse, '60); Einarson's gallocyanin (pH 1.6; Pearse, '60); and van Gieson's picrofuchsin. Histochemical techniques Polysaccharides.The periodic acidSchiff (PAS) reaction was employed on diastase-digested sections in a manner essentially similar to that described previously (Pipa and Cook, '58). Sections which had not been oxidized with periodic acid served as controls. The extent to which aldehyde groups contributed to any positive reaction observed was determined by employing the aniline-acetic acid blockading procedure of Lillie and Glenner ('57). The PAS reaction was either negative or greatly reduced by eliminating periodic acid oxidation, or by blockading.To decide whether structural ...

Mapping of Neuropeptides in the Crustacean Stomatogastric Nervous System by Imaging Mass Spectrometry

“…Figure 3k shows the MS image of a lipid ( m/z 806.57) that displays significantly higher intensity on the nerves and the sheath than that in the STG neuropil. This observation agrees well with previous knowledge that the sheath enclosing axons in invertebrates displayed remarkable similarities with vertebrate myelin sheath in terms of ultrastructure [54]. As expected, lipids distributed mostly in this whitish, fatty layer rather than the neuropil.…”

Microglia in invertebrate ganglia.

“…The existence of more than one type of invertebrate glial cells was proposed in 1883 by Vignal (14) and subsequently by a number of investigators (e.g., see refs. [15][16][17]. However, in these studies the term "microglia" was used only rarely and primarily on the basis of morphological criteria comparable to those known in vertebrate microglia (see refs.…”

Morphology of neuroglia in the antennal lobes and mushroom bodies of the brain of the honeybee

“…It shows the median (mcal;l and the lateral calyx (Ical) which can both be subdivided into lip (li), collar (co) and basal ring (brJ, the finger-shaped axonal branch points (f) within the pedunculus (ped) and the division of thc p-lobc into a dorsal (d) and a ventral part (v). The drawing in the lower left depicts the frontally sectioned u-lobe which is ganglia has a similar glial envelope (Wigglesworth, 1959;Pipa, 1961;Heywood, 1965;Hoyle, 1986;Meyer et al, 1987;Cantera, 1993, Tto et al, 1995. In the prothoracic ganglion of Munducu sextu the existence of six different types of such neuropile covering cells were demonstrated (Cantera, 1993).…”

“…Apart from a class of glial cells which forms the perineurium, he subdivided the other neuroglia into three classes according to their association with neuronal somata, processes, or neuropilar structures. Several subsequent investigations carried out to identify the glia in ventral ganglia of other insects yielded comparable classes of glial cells (Pipa, 1961;Heywood, 1965;Ali, 1973). More detailed classifications for glia of the metathoracic ganglion of Locusta and the prothoracic ganglion of Manduca sexta were provided by Hoyle (1986) and Cantera (19931, who suggested a rather large variety of different glial cell classes.…”