ALBERT

Notes: Five reproductive classes of cobia Rachycentron canadum, caught along the Gulf of Mexico and the south-east Atlantic coast of the U.S.A., are described during the annual reproductive cycle. These are based upon changes in the testicular germinal epithelium and the stages of germ cells that are present: early maturation, mid maturation, late maturation, regression and regressed. During early maturation, the germinal epithelium is continuous from the testicular ducts to the periphery of the testis and active spermatogenesis occurs throughout the testis. In mid maturation, the germinal epithelium near the ducts becomes discontinuous, but it remains continuous distally. In late maturation, a discontinuous germinal epithelium extends all along the lobules to the testicular periphery; lobules are swollen with sperm and there is minimal spermatogenesis. The regression class is characterized by a discontinuous epithelium throughout the testis, sperm storage and widely scattered spermatocysts. Spermatogonial proliferation also occurs along the lobule walls and at the periphery of the testis. In regressed testes, spermatogonia exist only in a continuous or discontinuous germinal epithelium, although residual sperm are nearly always present in the lobules and ducts. The presence or absence of sperm is not an accurate indicator of reproductive classes. At the periphery of the testis in the regression and regressed classes, the distal portions of lobules elongate as cords of cells containing spermatogonia and Sertoli cells. All reproductive classes can be identified in paraffin sections, although plastic sections provide better resolution. Using maturation classes defined by changes in the germinal epithelium to describe testicular development and spermatogenesis gives a more accurate picture than does using the traditional terminology.

Notes: Formation of hepatic melano-macrophage centres (MMCs) in Rivulus marmoratus was induced with the coccidian parasite Calyptospora funduli. Experimental infections were produced by feeding infected intestine and hepatopancreas from grass shrimp (Palaemonetes pugio) to individual parasite-free fish. Livers of fish sampled 5–150 days post-infection were examined histologically. Mild diffuse inflammation initiated during early merogony (5–8 days) consisted of eosinophilic granulocytes and heterophils. Liberation of merozoites (8–12 days) caused extensive hepatocyte degeneration and augmented leucocyte exudation. During gamogony (15–18 days) mononuclear phagocytes became a predominant component of the cellular exudate. Focal lesions, considered to be early MMCs, became apparent during early sporogony (20–25 days); they consisted of degenerating infected hepatocytes and inflammatory cells, and contained developing oocysts and degenerating macrogamonts, but no pigment. Early centres became visible grossly at 30 days as diffuse, yellow-tan foci within the hepatic parenchyma. Pigment content increased progressively, but melanin was never a major component. Oocysts first elicited a granulomatous response between 40 and 50 days. The study suggests that MMC formation in this instance is an inflammatory process in which mononuclear phagocytes recruited from peripheral circulation play a dominant role. MMC development appears to be elicited by macrogamont degeneration, whereas granuloma formation is probably a response to oocysts.

Notes: Abstract. The ultrastructurc of the macrogamont of Eimeria funduli was studied in hepatocytcs of the killifish Funldulus grandis and F. similis. The macrogamont developed in a parasitophorous vacuole (PV) that was bounded by two unit membranes probably derived from an envelope of modified host rough cndoplasmic reticulum (RER). The membrane adjacent to the host-cell cytoplasm was lined with ribosomes. whereas the membrane facing the PV was smooth and blebbed into the PV. Intravacuolar tubules were not observed in the PV. The macrogamonts had a single limiting membrane with lew micropores. Developing macrogamonts had abundant RER. few Golgi bodies, and a few small polysaccharide granules. Nuclei of developing macrogamonts had dispersed chromatin and compact nucleoli. Polysaccharide granules in developing and mature macrogamonts were identified with the periodic acid-thiocarbohydrazide-silver proteinate technique. In mature macrogamonts, polysaccharide granules as large as 1 –2 μm in diameter nearly filled the cytoplasm. The cytoplasm contained three kinds of inclusions that were associated with either the RER or Golgi apparatus. Inclusions identified as type I wall-forming (WF) bodies were small, dense, membrane-bound granules that developed from the Golgi apparatus. Inclusions identified as type II WF bodies were usually dense, irregularly shaped bodies that occupied RER cisternae. Some type II WF bodies had a heterogeneous content but most were homogeneous. A third type of inclusion was related to the cytoplasmic aspect of RER cisternae and consisted of tubules and vacuoles enclosed in a membrane.

Notes: Abstract. Ultrastructural studies were made on the inflammatory response in livers of two killifishes, Fundulus grandis and F. similis, experimentally infected with the coccidium Eimeria funduli. Coinciding with the formation and development of gamonts of E. funduli, changes took place in the liver and leucocytes appeared in that organ. Near areas of developing macrogamonts, many hepatocytes degenerated whereas others contained residual bodies which indicated sublethal damage. The damage was probably associated with merozoite formation and release. Filament-rich perisinusoidal cells hypertrophied during the development of E. funduli and contributed to walling off aggregates of oocysts from uninfected liver tissue. Leucocytes involved in the host response included lymphocytes, monocytes, heterophils, eosinophils and an unidentified third type of granulocyte. The heterophil was the first granulocyte to respond to the parasite and sometimes appeared to penetrate the parasitophorous vacuole of degenerating macrogamonts. Degranulating eosinophils were often observed near damaged tissues. Both the monocyte and eosinophil were phagocytically active. The monocyte was more phagocytically active and contained both host cells and parasite debris, whereas the eosinophil contained only debris from degenerating macrogamonts. The presence of immature granulocytes in the liver suggests that at least some granulocyte formation occurred in the liver.

Notes: Abstract. The ultrastructure of the microgamont and microgamete of the coccidium Eimerici funduli was studied in hepatocytes of the killifish Fundulus grandis and F. similis. During microgametogenesis, the nuclear chromatin condensed, marginated, then differentiated into a peripheral dense portion that became the nucleus of the microgamete and a central clear portion that remained in the gamont. Near each nucleus was a mitochondrion and four microtubules which were incorporated into the microgamete. In microgamonts, dense polysaccharide granules (50–60 nm diameter) were demonstrated with the periodic acid-thiocarbohydrazide-silver proteinate method. Flagella extended into the parasitophorous vacuole from basal bodies situated near nuclei. Microgametes budded from the surface of the microgamonts. The microgamete consisted of a nucleus, two flagella and basal bodies, a mitochondrion, a rudimentary basal body, four microlubules, a perforatorium, and a dense rod-like structure. The elongate nucleus was narrow anteriorly and bulb-like posteriorly. One of the flagella was attached to the body of the microgamete. A mitochondrion that was swollen anteriorly and constricted posteriorly ran alongside the nucleus. The four microtubules appeared to arise from a rudimentary basal body and were closely related to the mitochondrion. Two of them extended nearly the length of the nucleus. The rod-like structure appeared to develop from a thickening of the limiting membrane of the microgamont. Fertilization was not directly observed, but microgametes were found in the parasitophorous vacuoles of several macrogamonts.

Notes: Abstract. The tidewater silverside, Menidia beryllina, and the hogchoker, Trinectes maculatus, were exposed to south Louisiana whole crude oil (WCO) and its water-soluble fractions (WSF) to assess histopathological effects on their gills, olfactory organ, and liver. Both fishes were exposed to 5 mg WCO/1, 100 mg WCO/1, 5% WSF, and 50% WSF. Additionally, M. beryllina was exposed to 100 mg WCO/1 with 20 ppm Terramycin® to study possible complications caused by bacteria. Exposure of M. beryllina lasted 21-30 days, whereas experiments using T. maculatus continued for 38-60 days. Pathological changes in M. beryllina appeared by day 7 and became severe as experiments progressed to day 30. Histological alterations in the silverside included epithelial hyperplasia and fusion of gill lamellae, separation of respiratory epithelium from underlying tissue, hyperplasia of sustentacular cells of olfactory lamellae, necrosis of both neurosensory and sustentacular epithelium, extensive lipid vacuolation in hepatocytes, and atrophy and necrosis of intrahepatic exocrine pancreatic nodules. Of the tissues examined, the pancreas served as the most specific pathological indicator of oil pollution. In T. maculatus, hepatocytes of exposed individuals did not become vacuolated, and, except for gills exposed to 100 mg WCO/1, response by gills in the other three tests remained limited to slight hyperplasia. Olfactory mucosa of the hogchoker exhibited severe necrosis of both neurosensory and sustentacular cells in the high concentrations of oil, but no damage in low concentrations. The intrahepatic pancreas of fish exposed to all test-concentrations atrophied and became necrotic by the end of experiments. Limited studies using both Terramycin and a combination of Terramycin and WCO indicated lack of bacterial involvement in tissue damage in oil-exposed silverside, but the size of hepatic nuclei increased in the Terramycin-control fish, and the shape of lipid vacuoles appeared unusual subsequent to exposure to the combination. Menidia beryllina became hyperactive and refrained from feeding for up to 6 h after the initial administration of oil, whereas T. maculatus apparently never fed, and it exhibited hyperactivity after all exchanges of sea water and fresh oil. Deaths appeared to correspond both to degree of pathological damage and to exposure-concentrations. Partial to complete recovery was observed in gills, olfactory organ, and pancreas of M. beryllina exposed to WCO or WSF for 20 days and then maintained in oil-free sea water for 17 days.

Notes: Abstract. Blood samples from 961 estuarine and marine fish comprising 44 species from the northern Gulf of Mexico were examined for haematozoa. Trypanosoma mugilicola n. sp., characterized by an anteriorly situated nucleus (NI = 3.8), is described from the striped mullet (Mugil cephalus); it was also found in the hog-choker (Trinectes maculatus). Unidentified trypanosomes occurred in the hogchoker and bay whiff (Citharichthys spilopterus). Trypanoplasma bullocki is recorded for the first time from both the Gulf of Mexico, and from the southern flounder (Para-lichthys lethostigma) and Atlantic croaker (Micropogonias undulatus). Three species of haemogregarines are identified for the first time from the Gulf of Mexico, Haemo-gregarina platessae in the southern flounder, hogchoker, lined sole (Achirus lineatus) and blackcheek tonguefish (Symphurus plagiusa); H. mugili in the striped mullet; and H. delagei in the clearnose skate (Raja eglantera). A few piscivorous leeches from the region are evaluated as potential vectors.