Observations on the reproductive and larval biology ofBlennius pavo (Pisces: Teleostei)

Social behaviour and spawning of adultBlennius pavo kept in the laboratory are described. Eggs are deposited in batches on the walls of artificial spawning places (PVC pipes). One male guards and tends the eggs of different females in one spawning place. Larval hatching occurs in groups according to oviposition. Minimum incubation temperature is around 14–15°C. Larval survival in 1-1 rearing jars is not related to larval total length but to density of larval stock. An experimental population of laboratory reared juvenile and adolescentB. pavo displays a male to female ratio of 1:1.4. Factors possibly influencing the sex ratio of this littoral fish are discussed in view of the situation in its natural environment.     

Unusual testicular accessory organs, the testicular blind pouches of blennies (Teleostei, Blenniidae). Fine structure, (enzyme-) histochemistry and possible functions

The testicular blind pouches (TBPs) of Lipophrys canevae and Solaria pavo have an annual reproductive cycle with an active secretion phase during spawning, a regression phase correlated with necrotic processes during post-spawning, an inactive regeneration phase during inter-spawning and prespawning. As revealed by fine structure and enzyme-histochemistry the TBPs of L. canevae and S. pavo are involved in the production of steroid glucuronides, which possibly act as pheromones, Further functions are in the secretion of small amounts of sialomuciri and in lytic activity.     

The spermatic duct of blenniid fish (Teleostei,Blenniidae): Fine structure,histochemistry and function

Summary The annual changes of the spermatic duct ofSalaria pavo and the characteristics of the spermatic ducts of spawningAidablennius sphynx, Lipophrys adriaticus, L. dalmatinus, andParablennius incognitus are described by fine structural and histochemical methods. The spermatic duct ofS. pavo has an inactive phase during the interspawning period, a proliferation phase during the prespawning period, a phase of high secretory activity during the spawning period and a regression phase in the postspawning period. During spawning the spermatic duct ofS. pavo is involved in the secretion of glycogen, lipids, and sulfomucins and has similar fine structural and histochemical characteristics as the spermatic ducts ofA. sphynx, L. adriaticus, L. dalmatinus, andP. incognitus. The spermatic ducts of bleniid fish function (1) in stabilizing and continuation of the final differentiation processes of spermatozoa, (2) in storage of mature spermatozoa, (3) in nutrition of germ cells by glycogen, and (4) in the production of sulfomucins regarded as important for the mode of fertilization. Possible meanings of the varying size of the spermatic ducts in different species of blennies are discussed.     

Functions of the testicular gland in two blenniid fishes, Salaria (=Blennius) pavo and Lipophrys (= Blennius) dalmatinus (Blenniidae, Teleostei) as revealed by electron microscopy and enzyme histochemistry

The functions of the testicular gland in two different blenniid fishes, Salaria pavo and Lipophrys dulmutinus , are described by fine structural and enzyme histochemical methods. In the testes of the two fishes no mature spermatozoa are found. Sperrniogenesis occurs only until the spermatidal stage. Spermatids are released into the testicular gland. During the spawning period the testicular gland functions in differentiation of spermatids, nutrition of spermatids, and secretion of sialomucins. After spawning, the testicular gland has phagocytotic functions in resorbtion of remaining spermatids, which are transformed into lipids in the gland cells. During the interspawning period the testicular gland is a storage reservoir for lipids and phospholipids which are re-transformed into testicular gland secretion in the next reproductive season. Testicular gland cells themselves do not have steroidogenetic functions, but steroids are synthesized by interstitial cells homologous to Leydig cells in other fish. Possible explanations for the reduction of the testis in L. dalmatinus and implications of the testicular gland in taking over testicular functions are discussed.     

Ontogeny of feeding and respiration in larval Atlantic cod Gadus morhua (Teleostei,Gadiformes): I. Morphology

Cranial development in larval Atlantic cod Gadus morhua was studied throughout ontogeny using specimens treated by staining and clearing, scanning electron microscopy and histology. Newly hatched cod larvae have closed mouths, no operculii, five well-developed branchial arches, and transversii ventralis muscles. During the endogenous feeding (yolk-sac) stage, viscerocranial structures remain simple and nonarticulated. Six days after hatching at 5°C, articulation occurs between the quadrate/Meckel's cartilage and the hyomandibula/cranium. Integration of skeletal elements results in a functional jaw that facilitates the transition from endogenous to exogenous feeding. During later ontogenetic stages, the opercular apparatus and levator-operculi coupling develops, facilitating the transition of cutaneous to branchial respiration. Overall, feeding and respiratory needs are met by changes in form (including composition) and function during larval fish growth and are correlated with demands of energy acquisition essential to survival. © 1996 Wiley-Liss, Inc.     

Use of cues by Lipophrys pholis L. (Teleostei, Blenniidae) in learning the position of a refuge

The ability of Lipophrys pholis to remember the position of a refuge was tested in an artificial habitat under the influence of different visual clues. L. pholis learned the position of the refuge in the presence of a clue consisting only of a small black screen. They responded to this clue by moving towards it and pressing themselves up against it. Lego towers and a white screen clue did not provoke such a response. In a further experiment L. pholis continued to respond to the black screen in this way when the screen was moved to another location further from the refuge. After 12 days L. pholis learned to use the black screen in its new position as an indirect clue and navigate to the refuge directly without first approaching the black screen. These results suggested that when placed in a novel habitat the immediate reaction of L. pholis is to move quickly towards the first dark area they see but, with experience, they can use the position of large objects around them to navigate quickly and efficiently to a refuge.     

Asexual reproduction in Microstomum lineare (Turbellaria). I. An autoradiographic and ultrastructural study

The distribution of cells preparing for proliferation during asexual reproduction by paratomy in Microstomum lineare (Turbellaria) was investigated using the technique of exogenous tritiated thymidine ([³H]T) labelling and routine electron microscopy. The subsequent fates of labelled cells in developing and mature zooids were followed by fixing tissues at various intervals. The only labelled cells are mesenchymal and gastrodermal neoblasts, occurring along the whole worm without any special growth zones or axial gradient. Organ primordia develop as a result of locally dividing as well as of migrating cells.     

Biology of reproduction in the squirrel monkey (Saimiri sciureus): I. The estrus cycle

Results of a study to evaluate the length and specific characteristics of the estrus cycle in the squirrel monkey is presented. The estrus cycle was found to be 18–20 days long. Neither menstrual flow nor a cyclic swelling of the external genitalia was observed. A vulvar plug of desquamated vaginal cells was often, but not consistently observed a day prior to or on the day of estrus. Most pronounced cyclic changes in the exfoliated vaginal cells occurred during December through March of both the calendar years of the study.Supported by grant HDO 1952-03 from the United States Public Health Service.     

A Pirhemocyton-like parasite of the Blenny, Blennius pholis L. (Teleostei; Blenniidae) and its relationship to Immanoplasma Neumann, 1909

A light and electron microscopic study was made of a Pirhemocyton-like infection of the red blood cells of B. pholis, an intertidal fish. Electron micrographs show that polygonal particles occur in the cytoplasm of infected cells; these particles resemble the supposed icosahedral virus of Pirhemocyton. Inclusion bodies associated with the infection also resemble those seen in Pirhemocyton.Immanoplasma Neumann, 1909, was re-examined from blood films taken from three infected Scyliorhinus canicula collected in 1970. A marked similarity was noted between the inclusion bodies of the Blenny infection, Pirhemocyton and the Immanoplasma body. The nature of the numerous particles in the infected red blood cells of S. canicula is not known, therefore, Immanoplasma is only tentatively included in the group of known and suspected icosahedral cytoplasmic deoxyriboviruses.     

The morphology of the club glands on the dorsal fin of mature male shannies, Lipophvys pholis (L.) (Blenniidae: Teleostei)

The pelvic, pectoral, anal and dorsal fins of mature male, female and immature male Lipophrys pholis (L.) were examined by light microscopy for the presence of club glands. All fins except the dorsal showed a highly stratified epidermis and a thick cuticle. Club glands were present on the dorsal fin of mature male fisH but only during the breeding season. The development and decline of the club glands corresponds to the period of gonadal build-up and spawnout. Each club gland comprises several thousand bundles ofcolumnar cells. The columnar cells surround acentral pore which opens to the outside through a layer of Malpighian cells. The substance produced by the gland includes mucopolysacchdride. The function of the secretion is unknown and is discussed in relation to studies on similar glands in several Mediterranean blenniids.     

Morphology of the male reproductive systems of two Indopacific blenniid fishes,Salarias fasciatus and Ecsenius bicolor (Blenniidae,Teleostei)1

The testes and associated accessory organs of two blenniid fishes are described. The testicular organs of Salarias fasciatus consist of a testicular gland adjacent to the testis, chambered seminal vesicles serving as a reservoir for spermatozoa and testicular blind ouches. Ecsenirts bicolor has no testicular gland, has elongated chambered seminal vesicles whii are not used as a reservoir for spermatozoa, and has testicular blind pouches.     

The feeding biology of Hydrobia ventrosa (Montagu). I. The assimilation of different components of the food

The assimilation efficiencies for 7 species of diatoms, two of blue-green algae, and one bacterium have been measured in the deposit-feeding prosobranch Hydrobia ventrosa (Montagu). Two methods have been used, a chemical and a radiotracer one.The results of the first method were difficult to evaluate due to the fact that the time taken to clear the gut is ill-defined. The second method gave more consistent results.All diatoms are assimilated efficiently (60–71 %) as is the bacterium (about 75 %). The blue-green algae are less efficiently utilized; an Oscillatoria sp. was assimilated with an efficiency of about 50 % whereas a Chroococcus sp. was only assimilated with an efficiency of 8 %. It is concluded that resource partitioning based on differential utilization of micro-organisms cannot play an important rôle in the co-existence of Hydrobia ventrosa with other deposit-feeders.     

The spermatic ducts of salmonid fishes (Salmonidae, Teleostei). Morphology, histochemistry and composition of the secretion

Using light and electron microscopy, enzyme-histochemistry thin-layer chromatrography and photometry the functions of the spermatic ducts in salmonid fishes (rainbow trout, Oncorhynchus mykiss , Arctic charr, Salvelinus alpinus ; grayling, Thymallus thymallus ; whitefish, Coregonus sp.) were investigated. During spawning the spermatic duct of the Salmonidae has a high secretory activity: it synthesizes steroids, lipids (triglycerides, fatty acids, cholesterol esters, phosphatidylcholine), monosaccharides (glucose, fructose), proteins and enzymes (acid and alkaline phosphatase, glucuronidase and proteases). It is important for storage and resorption of spermatozoa. Interspecific differences exist in the storage capacity for semen.