The ultrastructure of globular hyaline microthrombi (GHM) is characterized by a spherical space lattice of frequently interconnected bundles of fibres of different width, with a periodic transverse striation and the fibrin-characteristic axial periodicity of 23 nm. These are surrounded by plump or slender bundles of fibres spreading radially over the surface which are only ocassionally interlinked. These filamentary formations of the so-called corona are also characterized by the fibrin-characteristic periodicity. Part of the GHM, however, lacks this axial periodicity, and periodic striation is then only visible in the radially extending fibrils of the corona. The spherical sace lattices with their plump or slender fibrillary fibrin bundles are also replaced by mosaic-like or nearly amorphous fine-grained precipitates. All intermediate stages between these main types of GHM can be found. The disappearance of the axial periodicity and of the fibrillary structure of the spherical space lattices is considered to be the morphological equivalent of seocndary fibrinolysis, here called endolysis, in the centre of the GHM. The morphogenesis of the GHM in states of shock of different aetiologies is discussed.

Acrodermatitis enteropathica (AE) was diagnosed in 2 siblings, boy and girl, at the age of 10 and 6 weeks. The family history is unremarkable except for consanguinity 5 generations previously. The clinical symptoms of the 2 patients conformed to the known features of AE, the gastrointestinal involvement loosing its significance with increasing age. In one patient in a stage of exacerbation the serum level of oleic acid (18:1) was lowered and of linoleic (18:2) acid slightly increased while that of arachidonic acid was decreased (Fig. 4). In both patients the serum zinc levels were significantly lowered. Under substitution with ZnSO4 the clinical condition improved and the serum zinc levels returned to normal. Histologically the small bowel mucosa was practically normal. Ultrastructural examination of jejunal biopsies revealed rather unspecific changes in the enterocytes in the form of numerous multivesicular bodies. The Paneth cells sometimes contained irregularly formed inhomogeneous structures within their cytoplasm. In addition the secretory granules varied in size and displayed a granular heteromorphic matrix. Frequently they were confluent and formed giant granules.

Histological, histochemical and ultrastructural studies were done on soft tissue surrounding alloarthroplastic joints. In 38 cases a prosthesis of the hip joint and in 2 cases of the knee had to be exchanged and replaced. In most of the cases the reoperation became necessary because the anchoring of the prosthetic parts in the bone loosened. Up to 18 months after the first operation infection was responsible for the malfunctioning in some cases. Other complications were luxation and material faults. The morphological changes are determined by the tissue reaction to the different alloplastic materials used and by the time interval they remained in the organism. The large polymerized acrylic cement particles are phagozytosed by multinucleated foreign body giant cells. About 12 months following the implantation of the artificial joints small double refractile particles appear and evoke characteristic morphological changes. The particles are abraded by the continuous friction of the moving alloplastic or metallic surfaces of the prostheses. Usually they are phagozytosed by histiocytes, which form large granulomas and undergo degenerative changes as is indicated by the ultrastructural and histochemical findings. These alterations are more pronounced and occur sooner in prosthesis with parts (rotation ball or cup.) fabricated by polyester than in those made by polyethylene. The abraded particles not only are transported to the inguinal lymphnodes, but also to the tissue between prostheses and bone, where they induce the same morphological changes as in the capsule. Hence the fibrous membrane separating bone and prostheses increases in width, and the spongy bone is partially destroyed by the proliferating histiocytes. It is assumed that by impairing the anchoring this foreign body reaction to the abraded alloplastic particles is the leading cause of the loosening of this kind of artificial joints.

Morphometry was performed on the left ventricular posterior papillary muscles of seven Wistar rats. The volume densities of myocardial cells, interstitial space, myocardial nuclei, sarcoplasm, mitochondria, myofibrils, ground substance and T tubules, and the surface densities of myocardial cells, mitochondrial membranes and T tubules, were calculated. Though only 1 ultrathin section per animal was evaluated the low standard errors of the means indicate that the method described here will be adequate in most experimental studies. Due to the anisotropy of the surfaces within myocardial cells, the papillary muscles were cut at an angle of 32.4 degrees to their longitudinal axis. This angle is derived from an equation published by Whitehouse (1974). The procedure to correct the loss of cristal membrane images from oblique sectioning is discussed.

In states of plasmic hypercoagulability and consumption coagulopathy ethanol favours the non-enzymatic polymerization of circulating soluble fibrinogen fibrin monomer complexes (FFMC) in vitro. The ethanol-gelation test of Godal and Abildgaard makes use of this phenomenon, called paracoagulation. The present studies show that it is also possible to visualize soluble FFMC by means of ethanol-gelation. In the electron microscope, FFMC, polymerized non-enzymatically by ethanol in the spleen, are characterized by plump or slender mycelioid fibrillar precipitates that show a uniform rhythmic transverse striation, a period-coincidental filamentary arrangement and an average periodicity of 23 nm. The ultrastructure demonstrates these ethanol-induced filaments to be in vitro-polymerized fibrin monomer derivatives. Paracoagulation with ethanol allows the identification of soluble FFMC in the tissue prior to the formation of highly polymerized fibrin-rich microthrombi, the established equivalents of the DIC-syndrome. The electron microscope studies also show the existence of a second type of fibrillary structure in the tissue polymerized by ethanol. This second type lacks the characteristic periodicity of fibrin and the period-coincidental arrangement of the filamentary structures, but is characterized by closely packed or chain-like aligned, irregularly sized spherical bodies. There is some evidence that these spherical bodies in vitro represent non-enzymatically polymerized complexes of fibrin monomers and fibrin degradation products (FDP), the equivalent of a limited local or generalized fibrinolysis in vivo.

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