Sperm storage and motility in the ovary of the marine sculpin Alcichthys alcicornis (Teleostei: Scorpaeniformes), with internal gametic association.

Elkhorn sculpin, Alcichthys alcicornis, is a marine teleost with a unique reproductive mode called "internal gametic association," in which sperm introduced into the ovary by copulation enter the micropylar canal of ovulated eggs in the ovarian cavity, but actual sperm-egg fusion does not occur until the eggs have been released into sea water. It is also known that this fish is a multiple spawner, which spawns at intervals of a few days for one month, and the sperm introduced into the ovary at the beginning of the spawning season retain their fertilizability for the entire period. To clarify how the fertilizability of sperm is maintained internally, the ultrastructure of sperm, the morphological characteristics related to sperm storage in the ovary, and the characteristics of sperm motility were investigated. Mature sperm generally have the normal form of teleost sperm, devoid of acrosomal structures. However, it was found that the midpiece is comparatively elongated and has a compact aggregation of many small-size mitochondria. The intraovarian sperm remained floating in the ovarian fluid throughout the spawning season. The sperm showed high motility in isotonic and weak alkaline solution, containing sodium ions, which was similar to the ovarian fluid of this fish. Sperm continued to move in artificial ovarian fluid for 7-14 days. Considering these results together, it is thought that the intraovarian sperm move throughout the spawning season due to the plentiful energy generated by the many mitochondria.     

Embryonic, larval and juvenile development of the roughskin sculpin,Trachidermus fasciatus (Scorpaeniformes: Cottidae)

Embryonic, larval and juvenile development of the catadromous roughskin sculpin,Trachidermus fasciatus, were described using eggs spawned in an aquarium. The eggs, measuring 1.98–2.21 mm in diameter, were light reddish-yellow and had many oil globules, 0.05–0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3–11.3°C. The newly-hatched larvae, measuring 6.9–7.3 mm BL, had a single oil globule, 9–10+25–26=34–36 myomeres and 6 or 7 large stellate melanophores dorsally along the gut. The yolk was almost resorbed, number of pectoral-fin rays attained 16–17, and two parietal, one nuchal and four preopercular spines were formed, 5 days after hatching, at 8.2–8.4 mm BL. The oil globule disappeared, and one supracleithral spine was formed, 11 days after hatching, at 8.9–9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7–10.3 mm BL. A posttemporal spine was formed 20 days after hatching, at 10.7–10.9 mm BL. The first dorsal fin spines (VII–VIII), second dorsal fin and anal fin rays (18–19, 16–18, respectively) appeared 23 days after hatching, at 12.0–13.7 mm BL. The pelvic fin spine and rays (I, 4) were formed and black bands on the head and sides of the body began to develop 27 days after hatching, at 13.8–15.8 mm BL. Newly-hatched larvae swam just below the surface in the aquaria. Preflexion larvae (8.9–9.5 mm BL), in which the oil globule had disappeared, swam in the middle layer, while juveniles (13.8–15.8 mm BL) began swimming on the bottom of the aquaria. Swimming behavior observed in the aquaria suggested that the fish started to change to a demersal existence at the juvenile stage.     

Spawning and subsequent copulating behavior of the elkhorn sculpinAlcichthys alcicornis in an aquarium

The spawning and subsequent copulating behavior of the elkhorn sculpin (Alcichthys alcicornis) were observed in an aquarium. Soon after the female was introduced into the tank, the male approached and initiated courtship behavior by unfolding all fins. Females which carried ovulated eggs eventually accepted the male and spawning progressed. Females which had not ovulated, repeatedly rejected the male’s advances. The onset of spawning in the female was indicated by fluttering of the pectoral fins and successive horizontal undulations of the posterior trunk which served to sweep the spawning site. The laying of several thousand eggs was preceded by the female taking several large inhalations of water through the mouth and a slight raising of the posterior trunk. The male continued various behavior related to courtship while the female approached spawning. After spawning, the female smoothed the egg mass into a thin layer by using the posterior trunk and anal fin. After spawning, and while the female flattened the egg mass, the male copulated repeatedly. No copulation was observed prior to spawning. Semen was observed to be emitted from the tip of the penis and to leak from the female’s genital pore. Eggs were fertilized externally by the emitted sperm in the case of females which had no prior copulating experience in the present breeding season. The entire reproductive behavior of the pair ceased, as the female left the spawning site after flattening the egg mass. The male remained near by, but did not aerate the eggs. During the breeding season, the area around the female’s genital pore and along both sides near the base of the anal fin became slightly distended and soft by the accumulation of a serous fluid. It is presumed that this edematous modification serves to flatten the egg mass for softness without crushing the eggs.     

Annual changes in fine structure of inner epithelial lining of the ovary of a marine sculpin,Alcichthys alcicornis (Teleostei: Scorpaeniformes), with internal gametic association

Alcichthys alciocornis has a viscous ovarian fluid in the ovarian cavity, which plays an important role in its unique mode of reproduction called internal gametic association (i.e., internal insemination and sperm-egg association but a delay in the physiological fertilization until spawning). Seasonal changes in fine structure of the inner epithelial lining and capillary endothelium of the ovary revealed that ovarian fluid originated as a result of the secretory activity of the tissues. The ovarian cavity of A. alcicornis is lined with an ovigerous lamella epithelium and an ovarian wall epithelium. During the spawning period, both epithelia actively secreted proteinaceous substances which seemed to constitute the ovarian fluid. The substances appear to be synthesized in the rough-surfaced endoplasmic reticulum from the material which was transported from the blood capillary, taken into the epithelial cells by endocytosis, accumulated in secretory vesicles via Golgi apparatus in the cells, and finally released into the ovarian cavity by exocytosis. Microapocrine secretion was also observed to occur in both epithelia. Secretory activity of both epithelia by exocytosis and microapocrine secretion showed distinct seasonal changes. Active exocytosis and microapocrine secretion were observed during the spawning period (April–May). These activities slightly declined during the degeneration period (May–June) and were lost during the early recovery period (July). During the mid to late recovery period (October–March), there was some exocytosis but no microapocrine secretion. © 1995 Wiley-Liss, Inc.     

Sperm storage and degradation in the ovary of a marine copulating sculpin,Alcichthys alcicornis (Teleostei: Scorpaeniformes): Role of intercellular junctions between inner ovarian epithelial cells

The morphology of female sperm storage during the spawning period and the morphology of sperm degradation after the spawning period were investigated by electron microscopy in a copulating teleost, Alcichthys alcicornis. The spermatozoa were maintained in the ovarian cavity, floating in the ovarian fluid during the spawning period. The spermatozoa then degenerated and were phagocytized by macrophages invading the ovarian cavity after the spawning period. In the ovary during the spawning period, horseradish peroxidase used as a tracer revealed tight junctional complexes connecting adjacent cells of the inner ovarian epithelia (ovarian wall epithelium and ovigerous lamella epithelium). This indicates that a compartmentalization of the ovarian cavity occurs during the spawning period. The junctional complexes were breached after the spawning period, as shown by the fact that horseradish peroxidase penetrated the ovarian cavity via the intercellular space between the adjoining ovigerous lamella epithelia. These results suggest that the spermatozoa in the ovarian cavity are isolated from the maternal immune system by the tight junctional complexes between the adjoining inner ovarian epithelia during the spawning period, and then are eliminated by immune cells following the breakdown of the junctional complexes after the spawning period. J. Morphol. 233:153–163, 1997. © 1997 Wiley-Liss, Inc.     

Conditions for initiation of fertilization of eggs in the copulating elkhorn sculpin

The reason for failure to initiate fertilization internally was examined in a cottid fish, the elkhorn sculpin, Alcichthys alcicornis which has internal gametic association and external fertilization. While eggs could be activated in calcium free hypertonic media but not be fertilized, fertilization occurred in isotouic media rich in calcium ions. The rate of fertilization was dependent on calcium concentration, and eggs were not fertilized in solutions with a calcium ion concentration of less than 0·57 mmol kg⁻¹. Calcium ions could be replaced to some extent by magnesium ions, but the former were the more effective in fertilization. Since calcium ion concentration of ovarian fluid of A. alcicornis was 0·41 mmol kg⁻¹, it was inferred that low calcium concentration in the ovarian fluid was the cause of the failure of A. alcicornis eggs to fertilize internally.     

Embryonic and morphological development of larvae and juveniles of the Amberjack,Seriola dumerili

Embryonic and morphological development of larvae and juveniles of the amberjack,Seriola dumerili Risso, are described using specimens raised at Yaeyama Station (Ishigaki Island, Okinawa Pref.), Japan Sea Farming Association. The specimens obtained from brood fish (3 females, 3 males) were treated with gonadotropin and spawned on 6th of April 1987. The eggs of amberjack are pelagic, spherical in shape and 1.01–1.17 mm in diameter. The yolk is roughly segmented and has a single oil globule 0.22–0.24 mm in diameter. The perivitelline space is narrow. During development, a few melanophores and no xanthophores were observed on yolk. Hatching took place 35 hrs. 15 min. after spawning out at temperatures 23.1–23.7°C. The newly hatched larvae were 2.84–3.04mm in TL with 27 (13+14) myomeres and an oil globule anteriorly situated beyond the head. 3 days after hatching 4.00 mm TL, the mouth opened. 10 days after hatching 4.26 mm TL, small denticles appeared on the margin of the upper jaw and there were 1 anterior and 2 posterior preopecular spines. At 5.96mm TL, notochord was slightly flexed. Caudal, dorsal and anal fins with rudiments of rays appeared at 8.00 mm TL. The specific numbers of all fin rays and spines were obtained in a juvenile 9.60 mm TL. In a juvenile 34.25 mm TL, 54 days after hatching, the characteristic brown band of amberjack had appeared on head. Some notable changes in relative growth were observed at 5 mm and 15 mm in TL.     

Embryonic development and newly hatched larvae of the little dragon sculpinBlepsias cirrhosus

This paper describes both embryonic development and newly hatched larval morphology of the little dragon sculpinBlepsias cirrhosus. The eggs ofB. cirrhosus are almost spherical, 3.0–3.2 mm in diameter, and have a yolk color of burnt orange. Development is very slow, being especially sluggish once the embryo appears. The embryo begins forming from the 10th day. In size, the early embryo is less than 1/6 of the yolk’s circumference. Incubation at 10°C takes about 200 days, 50 days shorter than the incubation period in a natural environment, with a mean water temperature of 11°C. The notochord length of newly-hatched larvae averages 11.1 mm. The larvae are developed so fully that the notochord is already flexing and the caudal and pectoral rays are forming.     

Embryonic,larval, and juvenile development of reared Cobitis striata fuchigamii (Cypriniformes: Cobitidae)

Ichthyological Research - In this study, the early development of Cobitis striata fuchigamii was described using aquarium-spawned eggs and juveniles. Egg yolk diameter after water absorption was...     

Ontogenetic development,allometric growth patterns,and daily increment validation of larvae and juvenile Culter alburnus

Fish ontogeny, allometric growth patterns, and otolith microstructure are fundamental in aquaculture and essential for understanding the early-life ecology of fish. Culter alburnus is a commercially important fish species and an excellent breeding target for aquaculture. In this study, newly hatched C. alburnus larvae were reared to the juvenile stage in a hatchery. Three days post hatch, the eyes, mouth, and intestine had developed, and the larval yolk sac had been completely absorbed. Fin rays started to differentiate in the flexion stage and were fully developed by the postflexion stage. Pigmentations were well developed in the juveniles. Culter alburnus larvae were characterized by 39–43 myomeres and 23–25 anal fin rays, swim bladder shape, and pigmentation. Head length, height, and musculature height showed positive allometric growth patterns, suggesting that head and trunk growth was prioritized. Positive allometric growth of the tail was simultaneous with the formation of fins, suggesting that swimming mode transformation, diet changes, and habitat shifts occurred after the start of the postflexion stage. Otolith growth increments in both the sagittae and lapilli were deposited daily, with the first increment formed on day 1 on the sagittae and day 4 of yolk sac absorption on the lapilli. Increments were thin and faint during the early developmental stage, gradually increasing to reach the broadest widths and the strongest contrast at the postflexion stage, which may be related to habitat shifts. This information will assist in the breeding and hatchery production of C. alburnus and establish suitable methods for analyzing this species’ spatiotemporal distributions and early-life traits.

     

Caddis larvae cases (Trichoptera,Limnephilidae) as anti-predatory devices against brown trout and sculpin

Brown trout (Salmo trutta L.) and sculpin (Cottus gobio L.) predation on the cased limnephilid larvae Glyphotaelius pellucidus (Retz.) (weak, broad leaf case), Limnephilus pantodapus McLachl. (weak, long cylindrical leaf case), L. rhombicus (L.) (rigid, hedgehog case) and Potamophylax cingulatus (Steph.) (rigid, cylindrical mineral case) was studied in the laboratory. The proportion of larvae ingested was significantly higher in brown trout than in sculpin for all four prey species. Brown trout captured larvae of all four species with equal success, but the higher number of unsuccessful captures resulted in a higher survival rate for P. cingulatus. It was significantly more difficult for sculpin than for brown trout to capture L. pantodapus larvae and to ingest all species except L. rhombicus. P. cingulatus larvae were never ingested by sculpins, and had the highest survival rate after capture by both fish species. In brown trout, the handling time of L. pantodapus was significantly longer than that of P. cingulatus. Sculpin had a significantly longer handling time of G. pellucidus than brown trout. L. pantodapus and L. rhombicus larvae feigned dead significantly longer than did those of G. pellucidus and P. cingulatus upon attacks from sculpins. L. rhombicus larvae also feigned dead for a long time upon attacks from brown trout. The survival rate of a larva attacked by sculpin or brown trout depends on both case rigidity as well as its behaviour. Brown trout was a more successful predator of cased caddis larvae than sculpin.     

Embryonic skin development and repair

Fetal cutaneous wounds have the unique ability to completely regenerate wounded skin and heal without scarring. However, adult cutaneous wounds heal via a fibroproliferative response which results in the formation of a scar. Understanding the mechanism(s) of scarless wound healing leads to enormous clinical potential in facilitating an environment conducive to scarless healing in adult cutaneous wounds. This article reviews the embryonic development of the skin and outlines the structural and functional differences in adult and fetal wound healing phenotypes. A review of current developments made towards applying this clinical knowledge to promote scarless healing in adult wounds is addressed.     

Spermiogenesis of the testes of juvenile hormone-treated silkworm larvae,Bombyx mori

• 1.1. To examine changes in the percentages of testicular cells such as 1C cells (spermatids and spermatozoa), 2C cells (G1 somatic cells, spermatogonia and secondary spermatocytes), 2–4C cells (somatic and germinal cells in S phase) and 4C cells (G2 somatic cells and primary spermatocytes), we isolated nuclei from the testes of silkworm larvae and subjected them to flow cytometric analysis.
• 2.2. In control testes, 1C cells appeared at day 0 of the fifth instar, increased gradually by spinning and increased steeply at 2 days later still spinning. The percentage of 2C cells decreased gradually after ecdysis to the fifth instar. The percentage of 4C cells increased from day 2 to day 5 of the fifth instar and decreased after day 11 of this instar. Cells in S phase remained constant through the fifth instar.
• 3.3. An injection of juvenile hormone analog, methoprene, at day 0 of the fifth instar did not inhibit spermiogenesis, but resulted in increased 2C cells and decreased 4C cells dose-dependently. In contrast, the same treatment at day 2 of the fifth instar did not change the percentages of 1C, 2C and 4C cells of the testes at all, suggesting that the testes changed sensitivity to the hormone at larval development.
• 4.4. Repeated injections of methoprene to induce the appearance of dauer larvae resulted in a complete block of the development of 1C cells.

     

Embryonic development of the tree frog, Hyla arborea

A staged series with time data and original photographs of the embryonic development of the tree frog, Hyla arborea are presented, following Gosner’s generalized table. To contribute to species specific embryological studies of anurans, the external features of development of this species were described. Duration of embryonic development, from fertilization to 25^th stage, is about 9 days at 20 ± 1 °C. Cleavage is holoblastic and unequal. Unlike the typical anuran development, neurular rotation was not observed in stage 15 or in any other stages. Other developmental stages resulted in a normal-looking. Embryos of H. arborea hatched at stage 20 or 21, which varied individually. Hatching occurred in the 4^th or 5^th day after fertilization. The mean total length of hatchlings was calculated as 6.38 mm. The mean size of ovum was estimated 1.4 mm in diameter.     

Comparative ecology of prickly sculpin,Cottus asper,and coastrange sculpin,C. aleuticus,in the Eel River,California

Synopsis We documented species' distributions, size structure of populations, abundance in mainstem and tributary streams, habitat use, and diets of prickly sculpin, Cottus asper, and coastrange sculpin, C. aleuticus, in the Eel River drainage of California, to determine the processes allowing coexistence of these very similar fishes. We observed prickly sculpins at 43 sites and coastrange sculpins at 34. The species co-occurred at 26 sites. Young-of-year coastrange sculpins were only observed within 42 km of the ocean, but young-of-year prickly sculpins were present throughout the species range. Mean, maximum, and minimum lengths of coastrange sculpins were positively correlated with distance from the ocean but no significant relationships were found for prickly sculpins. Absolute abundance of both species was highest in mainstem habitat (prickly sculpins = 0.6 sculpins m^–2 and coastrange sculpins = 0.4 sculpins m^–2) . Tributary densities of both species tended to be less than 0.1 sculpins m^–2. The species inhabited very similar habitats and had very similar diets. Coastrange sculpin populations in upstream areas were maintained by immigration from downstream areas in contrast with prickly sculpin populations that produced young-of-year fish throughout their range. Densities were probably not high enough for interspecific interactions to be important. The factors limiting the upstream distribution of the species may include high water temperatures, stability of the stream bed, and behavior of the fish. In the past, the range of sculpins within the Eel River drainage probably fluctuated with changing physical conditions. Recent introductions of exotic species that compete with and prey upon sculpins, and ongoing human activities in the drainage could result in major reductions in the distribution and abundance of one or both species.     

Embryonic development of the Pacific lamprey, Entosphenus tridentatus

Embryonic development of the Pacific lamprey, Entosphenus tridentatus, from Japan is described. Egg sizes averaged 1.249 mm (longest axis) and 1.145 mm (shortest axis), the time required for hatching being 11 days at 18 degrees C, shorter than previously reported for a lower water temperature (19 days at 15 degrees C). Early development in E. tridentatus proceeded at a similar rate to that in other lampreys, in spite of different rearing water temperatures for the latter, indicating possible specific differences in basic developmental rates.     

双斑蟋的胚胎发育

为了从组织胚胎学角度探究昆虫胚胎发育过程,以双斑蟋Gryllus bimaculatus de Geer的卵为实验材料,通过观察、记录蟋蟀胚胎每一天的形态变化并使用显微摄影方法记录胚胎发育过程,对蟋蟀卵胚胎发育全过程进行系统的观察和研究。根据胚胎形态的发育特点,可将整个胚胎发育过程分为7个阶段:卵裂期、囊胚期、原肠胚、无节幼体期Ⅰ、无节幼体期Ⅱ、无节幼体期Ⅲ、无节幼体期Ⅳ。经历14天,蟋蟀的头部、触角、3对足、尾部、腹部及背部都发育完全,整个胚胎发育随之结束。