Outer periarterial lymphatic sheath of the human spleen
Brozman, M.
Zeitschrift für Mikroskopisch-Anatomische Forschung 100(1): 56-66
1986
ISSN/ISBN: 0044-3107 PMID: 3524048 Document Number: 273623
By means of antisera against human hyaline cartilage not only pericapillary spongy sheaths are very distinctly visualized in the human spleen but also extracellular structures of periarterial lymphatic sheaths (PALS), particularly of their outer part. Thick reticular fibers from around the inner part of PALS with the central artery and around the arterioles a layered circumferential reticulum (CR), strengthened by transverse fibres between the individual layers. In the proximal section, consisting of both the outer and inner part, the PALS is most completely surrounded by the marginal zone (MZ), which is however missing in the distal section consisting only of the outer part, so that the PALS directly borders on the red pulp. In those places where the central artery has a rather excentric course, both the inner part of PALS and the MZ may be missing and the outer PALS is in close vicinity with the red pulp. The outer border of PALS is formed by the outermost layer with numerous openings allowing the passage of lymphocytes and other cells from the MZ or red pulp into the outer PALS and vice versa. The borderline with the inner part of PALs is very indistinct. The CR of the outer PALS is covered by a lining displaying alkaline phosphatase activity of varying intensity. It has presumably also other properties which may contribute to creating an environment through which lymphocytes can not only pass but can also stay there for a longer period of time and after activation by the corresponding antigen they can proliferate and develop into antibody forming cells.