Analysis of the non-recombining Y chromosome defines polymorphisms in domestic pig breeds: ancestral bases identified by comparative sequencing.

Sequences from 20 amplicons representing nine different loci and 11369bp from the short arm of the pig Y chromosome were compared using pools of DNA from different European and Chinese breeds. A total of 33 polymorphic sites were identified, including five indels and 28 single nucleotide polymorphisms (SNPs). Three high frequency SNPs within the coding regions of SRY were further analysed across 889 males representing 25 European and 25 Asian breeds or Lines, plus a European Line of Meishan. Two haplotypes seen to be associated with 'European' or 'Chinese' origin in the initial SNP discovery phase were found to be the most common in their respective groups of breeds in a more detailed genotyping study. Two further SRY haplotypes are relatively rare. One was found exclusively within Tamworth, at low frequency in Retinto, and in three Chinese breeds (Huai, Sahwutou and Xiaomeishan). The other uncommon haplotype is found exclusively in Bamajiang, two further Chinese breeds (Hangjiang Black and Longling) and two European rare breeds (Mangalica and Linderödssvin), but appears based on comparison with other suids to represent an ancestral sequence.

Genetic and physical mapping, expression analysis and partial sequence of porcine PER1.

The porcine PER1 gene was mapped to chromosome 12q1.4-->q1.5 using fluorescence in situ hybridisation. A polymorphic microsatellite marker (S0601) was isolated from a BAC clone shown to contain the PER1 gene. Linkage analysis assigned S0601 distal to ALOX12 on SSC12, providing further evidence for the conservation of synteny between HSA17 and SSC12. RT-PCR analysis demonstrated the expression of PER1 in all 11 tissues tested, consistent with the data from other mammalian species. Part of the PER1 gene was sequenced, homologous to exons 2-14 of the human gene and encoding the N-terminus of porcine PER1. The predicted amino acid sequence of the partial pig PER1 protein shares over 96% identity with its human orthologue.

Pathways of interstitial fluid and lymph flow in the liver acinus of the sheep and mouse.

In the acinus of the sheep and mouse liver, lymphatic vessels are restricted to the portal tracts. Vessels less than about 25 microm across form a network around portal venules, and are closely associated with the limiting plate of hepatocytes. The perisinusoidal space of Disse is continuous with the interstitial space of the portal tracts at the origin of the sinusoids. It seems likely that excess interstitial fluid derived from the sinusoids flows along the perisinusoidal space of Disse to enter the portal tracts near the portal venules, and then enters the small lymphatics which lie adjacent to those venules. It then enters the larger vessels, which are adjacent to hepatic arterioles and bile ductules.

Lymph pathways associated with three types of follicle structure found in gut-associated lymphoid tissue of horse ileum.

In the horse ileum, lacteals in the villi are continuous with prelymphatic intercellular channels and a plexus of lymphatic sinuses in the lamina propria that encircle the domes of the follicle/dome structures and proprial follicles. These sinuses may act as the major entry site for many of the lymphocytes migrating from gut-associated lymphoid tissue via the lymphatic system. Vessels from this plexus penetrate the muscularis mucosae and lymph flows into lymphatic vessels within the interfollicular tissue between the follicles of both follicle/dome structures and lymphoglandular complexes (LGCs). No lymphatic vessels leave the follicles, but intercellular pathways of the follicles are continuous with those in the surrounding interfollicular tissue and follicular sinuses around the base of the follicles. These pathways appear to provide the only available lymphatic route for lymphocytes leaving LGCs to enter the lymphatic system. Lymph from the interfollicular tissue enters deep submucosal lymphatic vessels, containing prominent valves, which drain into other vessels transporting lymph from the surface of the ileum.

Segmented filamentous bacteria associated with lymphoid tissues in the ileum of horses.

Segmented filamentous bacteria preferentially attached to the follicle-associated epithelium overlying the lymphoid tissue in samples of the terminal ileum from seven horses examined by scanning electron microscopy. The bacteria adhered to the apical membrane of the enterocytes by a holdfast segment. Each filament tended to be of uniform diameter, but the filaments ranged from 0.7 to 1.4 microns in diameter. The bacteria were usually absent from the adjacent villous epithelium.

Lymphoid tissues of the ileum in young horses: distribution, structure, and epithelium.

Lymphoid tissues in the ileum of young horses form raised plaques that are macroscopically visible from the mucosal surface. These are termed "ileal lymphoid patches". These patches are variable in size, shape and position within the ileal wall, occasionally lying along the site of mesenteric attachment. Within lymphoid patches, follicles exist in three different morphological forms: follicle/dome structures, proprial follicles, and lymphoglandular complexes (LGCs). In follicle/dome structures, the majority of the follicle lies in the submucosa and merges with a dome in the lamina propria through a gap in the muscularis mucosae. In proprial follicles, the majority, or all, of the follicle is found in the lamina propria, and in LGCs, the follicles lie in the submucosa and communicate with the intestinal lumen via a central invagination of epithelium that extends vertically through a gap in the muscularis mucosae. Follicle-associated epithelium covers the follicle/dome structures and proprial follicles. It consists of enterocytes, cells morphologically resembling M cells, intraepithelial lymphocytes, goblet cells, and amine-precursor uptake and decarboxylation (APUD) cells. The epithelium of LGCs is mainly populated by immature enterocytes, intraepithelial lymphocytes and goblet cells. Cells with coarse, long microvilli are also present. Information regarding the presence of LGCs in the small intestine is scant, but LGCs have been well described in the large intestine of many species. Further investigation will be required to determine if factors exist that are common to both the ileum of the horse and the large intestine of other species to influence the development of LGCs at these specific sites.

Ileal Peyer's patches in pigs: intercellular and lymphatic pathways.

BACKGROUND: The lymphatics of Peyer's patches disseminate immunological information from the gut and thus play a key role in protection of the body against environmental pathogens. The aim of this project was to describe the lymphatic pathways of these Peyer's patches in pigs, and the mucosal intercellular spaces which lead to these lymphatics. METHODS: Ileal tissue from living or freshly killed pigs was examined by light microscopy or electron microscopy, or was injected with Mercox (CL-2B, Japan Vilene Hospital, Tokyo) for scanning electron microscopy of corrosion casts. RESULTS: Intercellular fluid between intestinal epithelial cells passes through pores in the basal lamina to mix with that in the intercellular spaces and prelymphatic intercellular channels of the lamina propria and follicle domes. From there, lymph enters lacteals in the villi, or a branching network of vessels within the lamina propria. Small lymphatics penetrate the muscularis mucosae and are continuous with (1) lymphatic vessels which pass directly to the deep submucosa between follicles, or (2) lymphatic sinuses which lie adjacent to the follicles. This differs from the situation in sheep and rabbits. Basal lymphatics beneath the follicles convey lymph to vessels which leave the surface at the serosa. CONCLUSION: The differences in the structure and arrangement of the lymphatics of Peyer's patches between pigs, sheep, and rabbits will require further investigation to determine if such variation between species has an effect on the distribution of immune products to effector sites.

Lymphatic drainage from the distal small intestine in sheep.

Lymphatic drainage from the wall of the distal small intestine, important especially in young sheep as a major site of gut-associated lymphoid tissue, begins with a series of longitudinally oriented subserosal vessels. These vessels convey lymph to the mesenteric border of the intestinal wall and unite to form larger vessels which course through the mesentery to the mesenteric lymph nodes. These nodes lie towards the periphery of a broad, fan-shaped mesentery, adjacent to major arteries and veins. Mesenteric vessels convey lymph from the jejunum and part of the proximal ileum to the jejunal nodes. Lymph from most of the ileum is conveyed to caecal nodes. The larger mesenteric lymphatics have well formed smooth muscle and connective tissue layers surrounding the endothelium. They are often adjacent to, but rarely within, the connective tissue band anchoring the major arteries and veins to one or both lamellae of mesentery. Few anastomoses occur between vessels from opposing sides of the gut wall or the mesentery. Afferent lymphatics enter the subcapsular and trabecular sinuses of the nodes over most surfaces apart from the hilar region. Lymph flows through cortical tissue to the medulla, which occupies most of the node. In the medulla, sinuses occur within medullary cords as well as between them. Initial efferent lymphatics occur throughout medullary tissue. Efferent vessels emerge at a hilus then coalesce and drain into the jejunal or ileal trunk. The hilus of the node varies from a flat, poorly defined area on the lesser curvature, to a depression or groove. The latter commonly occurs in elongated jejunal nodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymph pathways associated with Peyer's patches in sheep.

Lymphatic drainage of the ileum associated with Peyer's patches begins with lymph entering a single lacteal of the villus, probably through intercellular flaps, which prevent retrograde flow to the interstitium. These lacteals are continuous with an interconnecting plexus of branching sinuses which surrounds the crypts and follicle domes in the lamina propria. Small vessels emanating from this plexus penetrate the muscularis mucosa, where lymph can either flow within septal vessels to the deep submucosa, or enter the follicular sinuses to move freely around follicles, and through gaps in septal walls. All lymph enters a deep submucosal network where retrograde flow is prevented by valves. Lymph is then conveyed through vessels passing between the fibres of the muscularis externa to other lymphatics, which transport lymph from the ileal surface to the mesenteric nodes.