Epsilon Archive for Student Projects

Abstract

The oviduct, together with its secretion, forms the environment in which gamete transport, sperm maturation, fertilization as well as early embryo transport and development occur. Morphological aspects, as well as immune cell distribution, have been described only to a limited extent regarding the pig oviduct. To better understand the reproductive physiology, more information is needed regarding morphology and infiltration of immune cells at different stages of the oestrous cycle.

The aim of this study was to investigate the morphological changes and the distribution of leukocytes in the sow endosalpinx throughout the oestrous cycle and at anoestrus. Nineteen crossbred sows (Swedish Landrace × Swedish Yorkshire) at late dioestrus (3), prooestrus (3), oestrus (3), early dioestrus (3), dioestrus (3) and anoestrus (4) were used. Oviductal samples from three different parts (isthmus, ampulla and infundibulum), taken immediately after slaughter, were immersion-fixed, embedded in plastic resin and stained with toluidine blue or stored in a freezer at -70°C until analysed by immunohistochemistry (prooestrus and anoestrus) with an avidin-biotin peroxidase method. Quantitative and qualitative examinations of oviductal epithelial and subepithelial connective tissue layers were performed by light microscopy.

During all stages, a lower degree of morphological changes in the epithelium (pseudostratification, mitosis and secretory granules) was found in the isthmus compared with ampulla and infundibulum. In the ampulla and infundibulum, pseudostratification, mitotic activity and secretory granules were high at prooestrus/oestrus. Cytoplasmic protrusions of epithelial cells with some extruded nuclei were prominent in ampulla and infundibulum at all stages except for oestrus and early dioestrus.

Lymphocytes as well as CD2 and CD3 positive cells were the predominant immune cells in the epithelial layer. The numbers of lymphocytes and CD3 positive cells did not differ among segments and stages. Numbers of CD2 positive cells did not differ between prooestrus and anoestrus while the numbers were significantly higher in the infundibulum than in ampulla and isthmus. Neutrophils were only occasionally found and mainly in the infundibulum.

In the subepithelial connective tissue layer, the two most commonly observed immune cell types were lymphocytes and plasma cells. The numbers of lymphocytes as well as CD2 and CD3 positive cells was lower in isthmus than in the other segments (P ≤ 0.001). Higher numbers of plasma cells (P ≤ 0.001) were found in infundibulum than in ampula and isthmus. The numbers of lymphocytes and plasma cells were not significantly different between stages of the oestrous cycle. However, the number of neutrophils differed and were highest at prooestrus in ampulla and infundibulum. The numbers of CD2, CD3 and CD79 positive cells did not differ between prooestrus and anoestrus whereas for CD14 and SWC3 positive cells, the numbers were higher at prooestrus (P ≤ 0.05) than at anoestrus.

In the oviduct, the morphology differed in ampulla and infundibulum with oestrous cycle stages which indicates an effect by ovarian steroid hormones. The immune cell infiltration was less influenced by cyclic changes. However, the immune cell infiltration (in the connective tissue) in the upper part, especially infundibulum, differed significantly from the one in the lower part, isthmus, indicating different immune functions within various parts of the oviduct.