The structural organization of the eye of Gammarus oceanicus conforms to that of other gammaridean species. Individual facets and a compartmentalization of the eye cuticle do not occur, though internally ommatidial groups are clearly separated from one another. The cones are bipartite; the rhabdoms are centrally fused and reach a maximum length and width of 30 μm and 10 μm, respectively. Four large retinula cells and one small retinula cell per ommatidium are developed with nuclei located below the fenestrated membrane. All eyes, though fixed at 0045, displayed the light-adapted condition with screening pigment granules surrounding the entire rhabdom and insulating the latter from the reflecting vesicles of auxiliary cells. With regard to quality and quantity of cell organelles, the retinula cells proved extraordinarily richly endowed: there were photic vesicles of 0.04 μm diameter along the edges of the rhabdom, multivesicular bodies with and without limiting membranes, two types of electron-dense spherical organelles (i.e. screening pigment grains and carotenoid-containing structures), mitochondria, microtubules, and unusual multilamellate bodies. The latter, surrounded by a membrane and associated with a grainy ground substance, are thought to be somehow related to the continuous light of the Arctic summer that G. oceanicus is subjected to. It is hypothesized that the unusual lamellate bodies are either involved in the task of meeting extra energy requirements during times of illumination or represent one stage in the conversion of shed microvillar material to residual bodies.

Immunoreactive glucagon (IRG) circulates in at least four molecular forms separable on Bio-Gel P-30, i.e. void volume material, IRG⁹⁰⁰⁰, IRG³⁵⁰⁰ and IRG²⁰⁰⁰. It is not fully established whether IRG⁹⁰⁰⁰ is produced by the pancreatic A cell. We have studied the content of IRG⁹⁰⁰⁰ in extracts of the pancreas of newborn and adult dogs, and its secretion from pieces of the pancreas in vitro. The same four IRG plasma fractions were detected in the basal incubation media of both the newborn and adult canine pancreas. Arginine stimulation produced a significant increase only in IRG³⁵⁰⁰ release from the adult pancreas, whereas release of both IRG³⁵⁰⁰ and IRG⁹⁰⁰⁰ was increased from the newborn pancreas. The majority of immunoreactivity in pancreatic extracts corresponded to IRG³⁵⁰⁰ in both newborn and adult dogs, although there was a significantly higher relative content of IRG⁹⁰⁰⁰ in the pancreas of newborn dogs. The canine pancreas is thus able to secrete IRG⁹⁰⁰⁰ in vitro, suggesting that some of the circulating IRG⁹⁰⁰⁰ originates from pancreatic A cells.

The gastrointestinal tract of representatives of all the vertebrate classes was investigated for the occurrence of serotonin-like immunoreactive cells using both polyclonal and monoclonal antibodies. In the alimentary canal of all the gnathostomes, but not in cyclostomes (Agnatha), sertotonin-like immunoreactive cells were detected. These cells showed a wide distribution and were found more or less throughout the gut of all the species, indicating that serotonin-like immunoreactive cells were established in the gut at the early stage of vertebrate evolution.

Endocrine-like cells in the laryngeal mucosa of adult rabbits were demonstrated by electron microscopy and by the Grimelius silver-impregnation method. Endocrine-like cells were found in both the ciliated pseudostratifred and non-ciliated stratified epithelium. Some of the cells reached the airway lumen with a tuft of microvilli. The cells contained small round granules of uniform size and with a core of variable electron density. Close apposition of nerve fibers to endocrine-like cells was occasionally seen. Endocrine-like cells were also seen in the epithelium of laryngeal submucosal glands. The epiglottic taste buds, similar in structure to the taste bud in the oral cavity, were occasionally seen in the vicinity of endocrine-like cells.

Changes in Ca²⁺ levels in echinoderm and medaka eggs were measured in relation to their cleavage cycles. Fertilized echinoderm eggs were treated with a calcium-ionophore (A23187), and Ca²⁺ efllux into the ambient solution was measured by the luminescence of a photoprotein (aequorin). The Ca²⁺ efflux changed cyclically with the same period as that of the cleavage cycle. The Ca²⁺ efflux decreased at the time of furrowing of every cleavage. These cyclic changes in Ca²⁺ efflux may reflect corresponding changes in the Ca²⁺ concentration in eggs. Luminescence of aequorin injected into medaka eggs indicated that the intracellular Ca²⁺ concentration changed cyclically with the same period as the cleavage cycle. The intracellular Ca²⁺ concentration was lowest at the time of furrowing. These results suggest that the constriction of the cleavage furrow isregulated by Ca²⁺ in an inhibitory manner. ATP concentration in echinoderm eggs was measured using luminescence of the luciferin-luciferase system. The ATP concentration remained almost constant following fertilization and throughout the cleavage cycles.

Immunoreactive neurons were detected in Periplaneta americana in the pacemaker loci of the optic lobe. Approximately ten cells on the dorsal side and about five cells on the ventral side of the clock loci which lie anteriorly to the second optic chiasm reacted with an anti-bovine pancreatic polypeptide (BPP) serum. So did nearly an equal number of cells with an antiserum raised against histidine-isoleucine containing peptide fraction 20-27 (PHI 20-27). Three to five cells were reactive with antisera against gastsrin, CCK (1-27), glicentin, β-endorphin and serotonin, with stronger reactivity appearing in the ventral locus. Several antisera reactive with the mammalian circadian pacemaker, the suprachiasmatic nuclei (SCN), such as those against vasoactive intestinal polypeptide (VIP), Arg-vasopressin (AVP), somatostatin and substance P did not show positive reactions in the cell bodies of the optic lobe, a location of the circadian pacemaker in the cockroach. Optic neuropiles contained materials immunoreactive to antisera against Met-enkephalin, VIP, AVP, oxytocin and hydroxy-indole-O-methyltransferase (HIOMT), a melatonin synthesizing enzyme, as well as those which stained perikarya. All antisera that gave a positive response in the optic lobe stained the central body too, though the staining pattern was somewhat different with the antiserum tested.

Under voltage-clamp conditions, delayed outward currents developed in fast (extensor digitorum longus) and slow (soleus) twitch muscle fibres of dystrophic mice (C57BL/6J dy^2j/dy^2j) were analysed using the double sucrose gap technique, and compared with those obtained in normal cells. In both normal and pathological muscles, fast- and slow- twitch fibres develop different delayed outward currents characteristic of their muscular type; the presence of a second slow component was found in both kinds of soleus muscle fibres. Results confirmed that no primary denervation effect is involved in murine dystrophy. Furthermore, the apparent shift of the muscular type occurring in dystrophic fibres due to an altered pattern of the nerve activity does not affect the properties of the delayed outward current.

An immunoelectron microscopic study by the double staining protein A-colloidal gold method was performed on the neurons in the guinea-pig duodenum using specific antisera to neuropeptides, i.e. Met-enkephalin-Arg⁶-Gly⁷-Leu⁸ (Met-Enk-Arg-Gly-Leu), substance P (SP) and peptide-histidine-isoleucine (1-15) (PHI (1-15)). Immunoreactive neuropeptides existed in the cored vesicles of 80-110 nm in diameter. The immunopositive cored vesicles were present in both somata and processes of some neurons. Occurrence and projections of three subclasses of Met-Enk-Arg-Gly-Leu immunopositive neurons (Met-Enk-Arg-Gly-Leu neurons) were described. Somata of the Met-Enk-Arg-Gly-Leu neurons occurred in the myenteric ganglion. Processes of the Met-Enk-Arg-Gly-Leu neurons with immunoreactive SP projected to all the layers of the duodenal wall except the mucosa. Neuronal processes containing cored vesicles with both immunoreactive Met-Enk-Arg-Gly-Leu and PHI (1-15) were mainly distributed in the submucous plexus. None of them occurred around the duodenal gland. Neuronal processes containing cored vesicles with only immunoreactive Met-Enk-Arg-Gly-Leu were small in number. They were present in the circular muscle layer, deep muscular plexus and submucous plexus. Difference in the projections of the three subclasses of the Met-Enk-Arg-Gly-Leu neurons may indicate that each of them performs different functions.

Connectin filaments linking myosin filaments to Z lines in chicken skeletal muscle interact with myosin rods but not with S₁ heads in vitro. An increase in turbidity of myosin rods, and heavy and light meromyosins was observed in the presence of connectin in KCl concentrations lower than 0.15 M, similarly to the case of intact myosin. The aggregate formation of myosin rods in the presence of connectin was observed by electron microscopy. It appears that the S₂ portion of myosin does not bind to connectin.

Effects of catecholamines on insulin release were studied using isolated rat pancreatic islets permeabilized with digitonin whose cytosolic Ca²⁺ concentration ([Ca²⁺]_i) was clamped with Ca-EGTA buffer. Adrenaline or noradrenaline dose-dependently inhibited insulin release induced by raising Ca²⁺ concentrations. The inhibitory effect of adrenaline was antagonized by yohimbine, an α₂-adrenergic blocker, but not by prazosin, an α₁-adrenergic blocker. Adrenaline also inhibited insulin release stimulated by increasing cyclic AMP or by activating protein kinase C in Ca²⁺-clamped islets. The findings suggest that catecholamines, via α₂-adrenergic receptors, inhibit insulin release by acting on a step independent of and probably distal to changes in [Ca²⁺]_i in stimulussecretion coupling.

Immunohistochemical staining using the peroxidase-antiperoxidase (PAP) method has demonstrated that glutathione S-transferases are exclusively localized in astrocytes and ependymal cells of adult rat brain, and that they are especially abundant in the nucleus. In contrast, oligodendrocytes and neurones do not show any immunoreactivity to the enzyme.

New polyhydroxylated cardiac steroids (I, II, III, IV, V and VI) were found in nuchal gland secretions of the snake, Rhabdophis tigrinus. The steroids contained an α-pyron ring at position 17 as those in bufodienolides but were not conjugated with suberoyl arginine. Hydroxylation occurred at position 3, 5, 11, 14; 3, 7, 11, 14, or 3, 5, 14, 16, respectively. This is the first report that the snake (Rhabdophis tigrinus) contains cardiac steroids in the nuchal glands.

Using serial thin sections, the distribution of neurons containing gastrin releasing peptide (GRP) and substance P (SP) in the myenteric plexus of the rat stomach was studied by immunohistochemistry. Three types of labeled neurons were found: 1) neurons with both immunoreactive GRP and SP, 2) neurons with only immunoreactive GRP, and 3) neurons with only immunoreactive SP. The present findings establish the coexistence of immunoreactive GRP and SP in the myenteric plexus of the rat stomach.