Histopathological changes caused by Enteromyxum leei infection in farmed sea bream Sparus aurata.

Histological examinations were carried out on the stomach, pyloric caeca and 4 different parts of the intestine, as well as the rectum, hepatopancreas, gall bladder and spleen of 52 sea bream Sparus aurata spontaneously infected by Enteromyxum leei. Fifteen fish from a non-infected farm were included as a control. Clinical signs appeared only in extensively and severely infected fish. We observed Enteromyxum leei almost exclusively in the intestinal tract, and very rarely in the intrahepatic biliary ducts or gall bladder. We observed heavily infected intestinal villi adjacent to parasite-free villi. Histological changes indicated a parasite infection gradually extending from villus to villus, originating from an initial limited infected area probably located in the rectum. The parasite forms were exclusively pansporoblasts located along the epithelial basement membrane. Periodic acid-Schiff (PAS)-Alcian blue was the most useful histological stain for identifying the parasite and characterising the degree of intestinal infection. We observed severe enteritis in infected fish, with inflammatory cell infiltration and sclerosis of the lamina propria. The number of goblet cells was considerably and significantly decreased in heavily infected fish. The intestines of 4 of the 5 survivor fish were totally free of parasites and showed severe chronic enteritis with a regenerative epithelium, suggesting that an acquired immune process may spontaneously eliminate parasites.

Pigeon circovirus infection: pathological observations and suggested pathogenesis.

Pigeon circovirus infection (PiCV) was diagnosed by light and transmission electron microscopy in 15 birds from five lofts in western France. Histopathological findings were suggestive of primary bursotropism of pigeon circovirus, followed by secondary systemic spread from the bursa of Fabricius, particularly to non-bursal lymphoid organs. The last stage of the disease was associated with various secondary (particularly bacterial) infections. In situ detection of apoptosis in the bursa of Fabricius indicated that PiCV was concomitant with an increase in bursal lymphocytic apoptotic events related to viral infection and leading to severe acquired immunosuppression.

[Comparative study of the diaphyseal osseous growth of the tibia between 3 and 12 weeks in 2 strains of turkey: histological and histomorphometric aspects]. / Etude comparée de la croissance osseuse diaphysaire du tibia entre 3 et 12 semaines dans 2 souches de dindes: aspects histologiques et histomorphométriques.

The comparative cortical growth of the tibiotarsus was studied in 2 turkey strains, one light, one heavy, between 3 and 12 weeks of age, using histological and histomorphometrical methods. The growth in thickness started earlier and was much faster and larger in the heavier turkey strain. The early ovoid shape of the cortex of the heavier strain and the difference between the thickness of the narrow and the thick cortical faces seemed to be related to the action of strong mechanical strains. Nevertheless the diaphyseal cortical ratio remained not significantly different in the 2 strains from the age of 3 weeks. The light strain exhibited during all the studied periods indicated a more variable mineral apposition rate and earlier and more extensive bone remodelling phenomena. Most of the growth in thickness parameters were significantly higher in the heavier strain when turkeys of the 2 strains were compared at an equivalent weight.