Ultrastructural studies of normal skin and epidermal papillomas of the flathead sole,Hippoglossoides elassodon

Summary Epidermal cells of normal fin web and of the epidermal papilloma of the flathead sole, Hippoglossoides elassodon, were compared by light and electron microscopy. The predominant cells of normal epidermis are squamous and are characterized by complex microvillous interdigitations between adjacent cells, numerous desmosome-like structures, terminal bars, prominent cytoplasmic filaments, and blunt, broad-based microvilli on the outer (free) surfaces of the superficial cells. The less numerous mucous cells of normal epidermis possess abundant ergastoplasm and mucus-filled vacuoles, but lack desmosome-like structures and cytoplasmic filaments.In contrast, in the epidermal papilloma, mucous cells are absent; and the tumor cells are without microvilli, desmosome-like structures, cytoplasmic filaments, and conspicuous ergastoplasm. The papilloma cells are in addition characterized by certain features not seen in normal epidermis, including prominent nuclear pores, very large nucleoli, nuclear dense bodies, vesicular mitochondria with few cristae and dense internal granules, and three types of distinctive cytoplasmic particles of possible viral nature.This investigation was supported by Public Health Service research grant CA 08158 from the National Cancer Institute, and American Cancer Society Institutional Grant No. IN-53 E.We are indebted to Miss Mary Bens for her indispensable technical assistance.     

Electron microscopy of the skin of the teleost,Hippoglossoides elassodon

Summary The normal skin of the pleuronectid fish, Hippoglossoides elassodon, is described by light and electron microscopy. The epidermis consists of 5 to 9 layers of cells, the majority of which are squamous cells and the minority mucous cells. The squamous cells are characterized by numerous desmosomes and associated cytoplasmic filaments. The mucous cells accumulate mucous droplets in vacuoles of Golgi origin and are observed apparently in the process of releasing their content at the free surface. The dermis consists of alternating lamellae composed of typical collagen fibers. Pigment cells are of three types: melanophores, iridophores (guanophores), and lipophores.This work was supported by Public Health Service Research Grant CA-08158 from the National Cancer Institute.     

Ultrastructural and histochemical study on gills and skin of the Senegal sole, Solea senegalensis

This study was undertaken to identify the normal ultrastructural features of gills and skin of the Senegal sole, Solea senegalensis, for a comparative measure to morphological alterations caused by environmental stressors such as reduced water quality and diseases. In the Senegal sole skin, four morphologically distinct layers were identified: cuticle, epidermis, dermis and hypodermis. The epidermis was composed of stratified epithelium containing three cellular layers: the outermost or mucosa layer, the middle or fusiform layer and the stratum germinativum or the basal layer. In the mucosa, two mucous cell types were differentiated: type A cells containing several round vesicles of different electron density and type B cells containing mucosomes of uniform electron density. Senegal sole have five pairs of gill arches, each containing two rows of well‐developed and compactly organized primary filaments and secondary lamellae. Fingerprint‐like microridges were observed on the surface of epithelial cells. The branchial lamellae epithelium consisted of different cell types: pavement, mucous and chloride. Between the chloride cells and the larger pavement cells, accessory cells were observed. Complexes of tight junctions and desmosomes were frequently observed between adjacent chloride and epithelial cells. Neutral mucosubstances and/or glycoconjugates were observed in the epidermis, dermis and hypodermis of S. senegalensis skin. Proteins rich in different amino acids, such as arginine and cysteine, reacted negatively or weakly positive in the epidermis, dermis and hypodermis. In gills, some mucous cells responded weakly positive to periodic acid‐Schiff (PAS) reaction but were strongly stained with Alcian Blue at pH 0.5, 1 and 2.5. When Alcian Blue pH 2.5–PAS reaction was performed, most mucous cells were stained blue (carboxylated mucins) and some mucocytes stained purple, indicating a combination of neutral and acid mucins. Proteins rich in cysteine‐bound sulphydryl (‐SH‐) and cystine disulphide (‐S‐S‐) groups were strongly detected in branchial and epidermal mucous cells, whereas lysine, tyrosine and arginine containing proteins showed very weak staining in both epidermal and branchial mucous cells. Protein reactions were strongly positive in the pillar cells, except for those rich in tryptophan, whereas the branchial cartilaginous tissue did not show an important reaction. The performed lipid reactions were negative in goblet and chloride cells. It is concluded from this study that ultrastructural and cytohistochemical features of the Senegal sole skin and gills may serve as control structures in both natural and aquaculture systems to monitor or detect environmental stress responses at the histological level.     

A comparison of the maturation and growth of female flathead sole in the central Gulf of Alaska and south‐eastern Bering Sea

Female flathead sole Hippoglossoides elassodon maturity appears not to be area dependent since the total length ( L _T) at which 50% were mature ( L _T50) was similar for the central Gulf of Alaska (333 mm) and south‐eastern Bering Sea (320 mm) areas. Likewise the age at which 50% were mature ( A ₅₀) was similar in the south‐eastern Bering Sea (9·7 years) and central Gulf of Alaska (8·7 years). The timing of female flathead sole spawning may also be similar between areas. Batch or serial spawning was indicated for flathead sole. Female flathead sole grew at a similar rate in both the Gulf of Alaska and Bering Sea. In contrast, males grew faster in the Bering Sea than in the Gulf of Alaska. Males grew more slowly than females in both areas after 5 years of age, and reached a smaller maximum L _T. The growth of both sexes was similar during 1993 and 1996 in the Gulf of Alaska.     

A comparative study of sperm postspawning destruction in flatfishes Hippoglossoides (Cleisthenes) herzensteini and Hippoglossoides dubius (Teleostei, Pleuronectidae)

Ultrastructural aspects of sperm destruction patterns were offered as additional cytological parameters for evaluation of the genus affinity of flatfishes Hippoglossoides dubius and Cleisthenes herzensteini. At the beginning of spermatozoan destruction, cell membrane in both species was found swollen, besides, discontinuity of membranes was observed, and membraneous parts were seen separating from sparmatozoa. We observed the ability of separated membraneous parts to aggregate to twisting conglomerates that wind round the objects of destruction. In H. dubius the membraneous conglomerates wound round spermatozoa, and after that such spermatozoa were phagocyted by follicular cells. In C. herzensteini, the membraneous conglomerates grasped the particles of destructed spermatozoa: the formed residual bodies were collected in the gonad lumen but not phagocyted by follicular cells. The expressiveness of the differences found in the pattern of sperm destruction is so considerable that, in the authors' opinion, these data are to supplement a list of criteria making reasonable reconsideration of the taxonomic status of C. herzensteini: its belonging to the genus Hippoglossoides, and establishing of the genus Cleisthenes as an independent rank.     

Differential cell composition and split epidermal differentiation in human palm,sole, and hip skin

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The respiratory mechanisms of the dusky flathead, Platycephalus fuscus (Platycephalidae, Scorpaeniformes)

The respiratory mechanisms of a shallow-water, marine and estuarine flathead, Platycephalus fuscus C. & V. are described. Morphological and behavioural adaptations enabling respiration while the fish is buried in fine, unconsolidated sediments are investigated and related to the ecology of the species.     

The swelling egg of the long rough dab, Hippoglossoides platessoides limandoides (Bloch)

The egg of Hippoglossoides platessoides limandoides swells when released into sea water. The swelling takes place entirely outside the ovoplasm and creates a large perivitelline space which can make up 85% of the total egg volume. Swelling occurs in both unfertilized and fertilized eggs although a small proportion of unfertilized eggs, believed not to have been activated, do not swell. Swelling is dependent upon the breakdown of cortical alveoli, together with an unusually soft and elastic chorion. The cortical alveoli, present in greater numbers than is usual in teleost eggs, release colloidal material when they break down on egg activation; adsorption of water by this material is responsible for the egg volume increase.     

The mode of hatching of the monogenean Entobdella soleae, a skin parasite of the common sole (Solea solea).

Observations have been made on the hatching behaviour of the larva of the monogenean Entobdella soleae and on the effects of various enzymes on the opercular cement of the egg. These observations indicate that hatching is brought about by a proteolytic hatching fluid which is produced by two pairs of ventral head glands and spread over the inner surface of the opercular joint by rotation of the larva about its longitudinal axis. After hatching there is no trace of the ventral head glands. Similar glands are present before hatching in the oncomiracidium of E. hippoglossi.     

Juvenile development of a flathead,Suggrundus meerdervoortii (Scorpaeniformes: Platycephalidae)

Juvenile development ofSuggrundus meerdervoortii was described, based on twelve specimens (12.9–43.8 mm SL) collected from off Yamagata Prefecture, Japan Sea. Two exterior openings in the lateral line scales were completed at ca. 35 mm SL, with the interopercular flap and iris lappet being visible at ca. 44 mm SL, these all being useful taxonomic characters. In juveniles and additional young and adult specimens (ca. 70–191 mm SL), the proportions of head length, snout length, orbital diameter, caudal peduncle depth and caudal fin length decreased with growth; interorbital width decreased rapidly until ca. 70 mm SL, but more or less stabilised thereafter (70–191 mm SL).     

Larval morphometry of the Japanese flounder,Paralichthys olivaceus

The larval development of the Japanese flounder,Paralichthys olivaceus, was surveyed using two types of morphometric analyses, modified allometry and polar coordinate analysis by principal component analysis (PCA). In the former, centroid size was used as a growth index instead of total length (TL), such enabling the determination of more detailed changes in each character than ordinary allometry based upon TL. Polar coordinate analysis disclosed two remarkable inflexions during the larval development ofP. olivaceus. Postlarvae ofP. olivaceus were found to undergo four developmental phases. From the point of view of metamorphosis, the phases were named drifting larva, premetamorphic larva, metamorphic larva and postmetamorphic larva, respectively. These phases were also tested by other characters related to flounder metamorphosis.     

Larval morphology of the lesser housefly, Fannia canicularis

The morphology of all larval instars of Fannia canicularis (Linnaeus) (Diptera: Fanniidae) is documented using a combination of light and scanning electron microscopy. The following structures are documented for all instars: antennal complex; maxillary palpus; facial mask; cephaloskeleton; ventral organ; anterior spiracle; Keilin's organ; posterior spiracle; fleshy processes, and anal pad. Structures reported for the first time for all instars include: two pairs of lateral prominences on the prothoracic segment; additional ventrolateral prominences on the second thoracic segment, and a papilla at the base of the posterior spiracle. Other structures reported for the first time are anterior spiracles in the first instar and a serrated tip on the mouthhook in the second instar. A trichoid sensillum on the posterior spiracular plate, representing a sensory organ otherwise unknown in the Calyptratae, is described in the second and third instars. Results are discussed and compared with existing knowledge on dipteran larval morphology.     

Pit-Building Decisions of Larval Ant Lions: Effects of Larval Age, Temperature, Food, and Population Source

Foraging decisions are an integral component of growth and maintenance and may reflect both environmental and genetic effects. We used a common garden experiment to evaluate the effects of food, temperature, and population source on pit-building decisions of the larval ant lion Myrmeleon immaculatus. In a laboratory common garden experiment, first-instar larvae from two southern (Georgia, South Carolina) and two northern (Connecticut, Rhode Island) populations were reared for 14 months in incubators under high- and low-food and high- and low-temperature regimes. For all populations, there was no effect of larval age on pit-building behavior. All larvae built and maintained pits more frequently at high temperatures than at low temperatures, and larvae in the low-food treatments built and maintained pits more frequently than larvae in the high-food treatments. Larvae from the southern populations built and maintained pits more frequently than larvae from northern populations. These results suggest that regional differences in foraging behavior may contribute to latitudinal gradients in life history strategies seen in this insect.     

Age,growth, and maturity of the Indian flathead Platycephalus indicus in the waters around Okinawa-jima Island,Japan

Ichthyological Research - Indian flathead Platycephalus indicus (Platycephalidae) is an important fishery resource in tropical and subtropical waters. However, there have been few studies of its...