Monoaminergic Systems in the Hypothalamus of the Acanthopterygian Chelon labrosus (Risso, 1826), with Special Reference to the Organon Vasculosum HypothalamiGómez‐Segade, Pablo; Anadón, Ramón; Gómez‐Segade, Luis
doi: 10.1111/j.1463-6395.1989.tb01047.xpmid: N/A
Distribution of biogenic amines in the diencephalon of the advanced teleost Chelon labrosus was investigated by formaldehyde‐induced fluorescence. We have found three closely interrelated bright yellow‐green fluorescent monoaminergic cell groups having numerous cerebrospinal fluid‐contacting cells with dendritic processes that protrude into the lumen of the third ventricle. The most rostral of them, the organon vasculosum hypothalami, located dorsally at the mid and caudal hypothalamus level, showed under electron microscopy some monoaminergic cells and others with an abundant smooth endoplasmic reticulum. The cerebrospinal fluid‐contacting processes of both cell types, in association with numerous fibres, terminal buttons and some capillaries, constitute a thick and complex intraventricular mat. The other two fluorescent regions, nucleus recessi lateralis and nucleus recessi posterioris, border the lateral and posterior recesses of the hypothalamus.
Fine Structure of the Labial Gland in Macrotermes bellicosus (Isoptera, Termitidae)Billen, J.; Joye, L.; Leuthold, R. H.
doi: 10.1111/j.1463-6395.1989.tb01050.xpmid: N/A
The labial gland in M. bellicosus corresponds with the acinar type, and occupies the greater part of meso‐ and metathorax. The acini comprise three secretory cell types, in addition to the central ductule cells and the epithelial cells that make up the efferent ducts. Cell types are mainly distinguished by the size and appearance of their secretory vesicles and the extent of the microvillar contact area with the ductule cells. They probably produce a proteinaceous secretion that may contain digestive enzymes. The labial gland acini in soldiers, on the other hand, contain only one type of secretory cell, which is not comparable with any of the cell types in the worker caste. This difference is in agreement with the multifunctional role of the labial gland according to the termites' polyethism.
Histological and Immunohistochemical Studies of the Neurohypophysis of Primitive Teleosts, the OsteoglossidaeTsuneki, K.; Nozaki, M.
doi: 10.1111/j.1463-6395.1989.tb01051.xpmid: N/A
The neurohypophysis of three species of the Osteoglossidae (Osteoglossum bicirrhosum, Scleropages jardini and Heterotis niloticus) was studied histologically. The rostral part of the neurohypophysis abuts on the pars distalis of the adenohypophysis, but does not interdigitate with it. The caudal part of the neurohypophysis is stained densely with aldehyde fuchsin and extensively interdigitates with the pars intermedia, forming a neurointermediate lobe. This organization of the neurohypophysis is intermediate between that of holosteans and that of non‐osteoglossomorph teleosts. The median eminence‐like features of the rostral part of the neurohypophysis are distinct in the Osteoglossidae in contrast to non‐osteoglossomorph teleosts. In Osteoglossum bicirrhosum, immunohistochemical study reveals the presence of somatotropin release‐inhibiting factor‐like substance in the rostral part of the neurohypophysis. Fibers immunoreactive to anti‐arginine vasopressin occur in the neurointermediate lobe almost exclusively. These observations also may support the assumption that the rostral part of the neurohypophysis corresponds functionally to the median eminence. For comparison, the occurrence and distribution of somatotropin release‐inhibiting factor‐like substance, luteinizing hormone‐releasing factor‐like substance and arginine vasopressin‐like substance in the neurohypophysis of Gymnarchus niloticus are described.
The Oral Papilla of the Lancelet Larva (Branchiostoma lanceolatum) (Cephalochordata)Andersson, Eva; Olsson, Ragnar
doi: 10.1111/j.1463-6395.1989.tb01052.xpmid: N/A
The oral papilla is a prominent larval organ in the lancelet, which develops early during ontogenesis and disappears completely at metamorphosis. Electron microscopic studies indicated that the prevailing theories of its function are unlikely. Its cells lack the cytological characteristics of sensory or mucus producing cells, and the organ is not equipped with a tuft of flagella. It was not possible to reveal the function of the papilla, but its cells seem to be involved in a pronounced substance transport through the basal cell membrane as well as in the cytoplasm. Apical specializations indicate exo‐ or endocytotic activity and vesicles imply some exchange also between papilla cells and the sea water.
Sperm Structure in the PsocopteraKing, P. E.; Ahmed, K. S.
doi: 10.1111/j.1463-6395.1989.tb01053.xpmid: N/A
An account is given of the ultrastructure of the sperm in Psocoptera. Three main types of sperm occur. Type one, in Suborder Trogiomorpha, is an uncoiled long sperm with a filamentous head and a flagellum containing two or three lateral ridges and two central tubules. Twenty three per cent of this type has two axonemes and four mitochondrial derivatives. The second type, in the Suborder Psocomorpha, lacks both central tubules and lateral ridges. Four per cent of this type contain biaxonemes and four mitochondrial derivatives. In the third type, in the Suborder Troctomorpha. 100% of the sperm have two axonemes and two mitochondrial derivatives. The possible function and the method of locomotion of these types are described. The similarity between sperm structure in the Psocoptera and in Anoplura and Mallophaga suggests a close phylogenetic relationship between the three orders.