Scanning electron microscopy of swine lymphoid organs.

The aim of this investigation was to study by scanning electron microscopy the structure of several swine lymphoid organs (lymph nodes, Peyer's patches, and tonsil). Two groups of animals were used: six-month-old pigs and six- to nine-day-old piglets. Samples were jet-washed to eliminate most free cells in order to observe the reticular framework of these organs more clearly. Peyer's patches in piglets showed two types of villi. In one of them the cellular types were absorptive cells and goblet cells. The second type of villi were shorter and wider, with M cells characterized by presenting long, thick microvilli over their surfaces. Peyer's patches of pigs did not show this second type of villi but were usually covered by absorptive villi. The soft palate tonsil was similar in both groups of animals with its surface epithelial cells full of microfolds, partially and frequently obscured by microorganisms. The appearance of the surface epithelium in the same crypt was different depending on the area. There was a large number of holes through which cells apparently passed towards the crypt lumen. The medulla in the lymph nodes was at the periphery and showed a dense reticular framework. Cortex-like lymphoid tissue was formed by lymphoid follides and diffuse lymphoid tissue with high endothelid venules and lymphatic sinuses. The serosal surface of lymphoid organs was formed either by a typical mesothelial cell layer (small intestine) or by loosely arranged connective fibers (lymph nodes).

Neospora caninum infection in a Napolitan mastiff dog from Spain.

Fetal neosporosis-associated myeloencephalitis was diagnosed in a 4-month-old Napolitan mastiff dog from Spain. Neospora caninum tachyzoites and tissue cysts were observed in lesions in the central nervous system and the diagnosis was confirmed by immunohistochemical staining with anti-N. caninum monoclonal and polyclonal antibodies.

A sequential histopathologic and immunocytochemical study of chickens, turkey poults, and broiler breeders experimentally infected with turkey rhinotracheitis virus.

The histopathologic changes and the distribution of turkey rhinotracheitis virus (TRTV) antigen in the respiratory and reproductive tracts of experimentally infected chickens, turkey poults, and broiler breeders is described. TRTV antigen was detected using both immunofluorescent staining of cryostat sections and immunoperoxidase staining of formalin-fixed tissues. Viral antigen was observed associated with the cilia of the epithelial cells of turbinates, trachea, and lung. No TRTV antigen and no histopathologic changes were detected in the conjunctiva of any of the sacrificed birds, or in the reproductive tract and central nervous system of broiler breeders. The main histopathologic lesions and sites of TRTV replication were observed in the ciliated epithelial cells of turbinates and lung. These findings bring forward new information about pathologic changes and TRTV antigen distribution in tissues of experimentally infected birds.

Histochemical and immunohistochemical study of the mucosal lymphoid system in swine.

Enzyme histochemical and immunohistochemical techniques were used to examine palatine tonsils and aggregated lymphoid follicles (Peyer's patches) of the ileum in 6- to 9-day-old and in 6-month-old pigs. Histochemical techniques were used to detect alpha-naphthyl-acetate esterase (ANAE), alpha-naphthyl-butyrate esterase (ANBE), beta-glucuronidase, adenosine triphosphatase (ATPase), and acid phosphatase (AcP). Nonspecific esterases (ANAE, ANBE) were detected in macrophages, T-cell area lymphocytes, eosinophils, fibroblastic reticular cells (FRC), follicular dendritic cells (FDC), and interdigitating cells (IDC). beta-Glucuronidase reactivity was strong in macrophages, eosinophils, FDC, and IDC, and weaker in FRC. Adenosine triphosphatase reactivity was detected in B-cell area lymphocytes, FDC, FRC, and IDC. Cell types with acid phosphatase reactivity were macrophages, FDC, FRC, and IDC. Nonepithelial cells of tonsils and aggregated lymphoid follicles of the ileum had similar enzymatic reactions. In Peyer's patches, however, epithelial cells were positive for all enzymes studied; in tonsils, only nonspecific esterases were detected. Immunoperoxidase techniques were used to detect S-100 protein and cytoplasmic immunoglobulins (IgG, IgM, and IgA). The S-100 protein was detected in lymphocytes, FDC, and FRC of tonsils and Peyer's patches; in tonsillar epithelial and endothelial cells; and in IDC of Peyer's patches.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical localization of S-100 protein and lysozyme in canine lymph nodes and lymphomas.

The present study concerns the immunocytochemical localization of S-100 protein and lysozyme in the cells of canine lymph nodes and lymphomas. In the normal canine lymph node S-100 protein was detected in follicular dendritic cells (FDCs) and in interdigitating reticulum cells (IRCs). S-100 positive cells were found in thirteen out of twenty-four lymphomas, scattered throughout the tumour or in follicles. In three cases (two cutaneous lymphomas and one nodal lymphoma) the number of positive cells was high, although the main proliferating cell population was S-100 negative. In normal lymph nodes lysozyme immunoreactivity was found in the cytoplasm of cortical and medullary histiocytes. Lymphomatous cells were negative for lysozyme, although in three cases lysozyme-positive cells were present between the lymphatic cells. The possible origin of these S-100 or lysozyme positive cells is discussed. It is suggested that S-100 protein and lysozyme can be used as useful markers for these two types of dendritic cells and for macrophages.

Experimental infection of chamois (Rupicapra pyrenaica parva) with Sarcoptes scabiei derived from naturally infected goats.

Two chamois (Rupicapra pyrenaica parva) out of a group of three were experimentally infected with Sarcoptes scabiei derived from a naturally infected domestic goat. One of the chamois presented the first clinical manifestations (papules and desquamation) at 7 days post-infection, after 22 days crusts and alopecia appeared and after 41 days pruritus. The other chamois presented desquamation after 15 days and papules after 21 days and crusts and alopecia after 31 days. All these clinical manifestations continued to spread and when the animals were treated at 84 days post-infection, pruritus, papules and crusts were first to disappear, there being no evidence of their presence at 99 days post-infection, when the second treatment dose was applied. The desquamation and alopecia disappeared at 114 days post-infection, by which stage both animals were considered to have been cured. The results of the skin scraping was negative in both chamois until 54 days post-infection and it became negative again after 84 days, when the first treatment dose was applied. Biopsies showed different levels of hyperkeratosis and a marked epidermic hyperplasia with formation of small crusts. Superficial epidermis presented marked vasodilatation and also infiltrated inflammation. None of the biopsies carried out showed the presence of parasites. The non-infected chamois, which was kept in the same compound as the other two, did not present any clinical manifestations compatible with infection by S. scabiei throughout the entire period of the experiment.