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Objectives: The reproducibility of clinical tests for skin extensibility and consistency, essential for differentiating between types of Ehlers-Danlos syndrome (EDS) and benign joint hypermobility syndrome (BJHS), is unknown. Paraclinical methods may provide objective differential diagnostic methods., Methods: Six EDS, 11 BJHS, and 19 controls completed the trial. We analysed the overall inter-examiner agreement on clinical tests for skin extensibility and consistency, in addition to analyses on suction cup (SC) and soft tissue stiffness meter (STSM) methods., Results: Overall agreement on tests for skin extensibility and consistency varied between 0.44 and 0.72. Extensibility evaluated by SC showed an insignificant difference between EDS patients and controls (p = 0.056). Consistency evaluated by STSM showed significant differences (p = 0.001)., Conclusions: Overall inter-examiner agreement on clinical tests for skin extensibility and consistency was below 0.80, which was required a priori to conduct a reproducibility study. Further refinement of tests and a training phase are necessary. The SC and STSM results are encouraging but must be reproduced in a larger study population.

Background: Elastic fibres in the inherited hypermobile disorders are probably abnormal on the inherited grounds. The abnormality may contribute for diagnosis and investigation of connective tissue biology., Objective: The abnormality will be specific for every disorders and disclosed in the age-dependent change when exposure-dependent change was excluded., Materials and Methods: Skin specimens from Ehlers-Danlos syndrome and hypermobile syndrome, Marfan syndrome, Osteogenesis imperfecta type I, homocysteinuria and normal controls are studied by routine electron microscopy. Age-dependent ultrastructural change of broad elastic fibres was evaluated in reticular dermis., Results: Age-dependent change was categorized in infantile, adolescent, adult and senile pattern. Infantile pattern showed normal ultrastructure. Degeneration was first found in adolescent pattern by disarrayed microfibrils and degenerate matrix. Degeneration proceeded in adult pattern and ended in senile pattern. Typical abnormality developed in adult pattern. Ehlers-Danlos syndrome and hypermobile syndrome showed no specific abnormality but the degeneration began earlier and was severer than the control. Marfan syndrome showed defects of microfibrils and matrix surface. Moth-eaten figure was characteristic. Osteogenesis imperfecta showed abnormal matrix and revealed homogenous bulges of matrix. Homocysteinuria was specified by numerous microfibrils on the matrix surface in infantile pattern., Conclusion: Abnormality of elastic fibre was recognized in the reticular dermis of elbow. Ehlers-Danlos syndrome and hypermobile syndrome showed no specific abnormality but the degeneration was more intensive than the control. Abnormality of Marfan syndrome was degeneration of elastic microfibrils and matrix surface, Osteogenesis imperfecta was characterized by excess amount of matrix. Homocysteinuria revealed numerous microfibrils. Ultrastructural abnormality provided grounds for studies on histopathology and biology of elastic fibre.

The effect of photodynamic therapy on tape-stripped normal human skin was explored ultrastructurally. Back skin areas of 3 healthy Caucasian volunteers, 2 men and 1 woman, were tape-stripped 10 consecutive times followed by topical treatment with 5-aminolevulinic acid (20%, w/w) for 4 hours under occlusion (Tegaderm). Then the areas were irradiated for 30 minutes with Waldman PDT 1200 lamp (570-650 nm) with a total dose of 70 J/cm(2). Full-thickness punch biopsies were taken immediately after irradiation, and at 3 and 24 hours for electron microscopy examination. Photodynamic therapy caused morphological alterations mainly in the epidermis. Keratinocytes became oedematous and tonofilament bundles were split, but desmosomes remained normal. Many keratinocytes contained large intracellular vacuoles and extremely electronlucent cytoplasm implying cell damage. Although the majority of Langerhans cells were unaffected isolated Langerhans cells became apoptotic at 3 hours. The melanocytes preserved their normal morphology. The epidermal alterations recovered 24 hours after the irradiation. Inflammatory cell infiltrates were evident at 3 and 24 hours but no other dermal changes were observed. In conclusion, photodynamic therapy with 5-aminolevulinic acid affects mainly keratinocytes and can trigger apoptosis in Langerhans cells while melanocytes appear refractory, at least morphologically, to photodynamic therapy., (Copyright John Libbey Eurotext 2003.)

We report a case of intravascular large B-cell lymphoma. A 52-year-old man gradually developed dementia and abnormal behaviors, which were later accompanied by spastic paraplegia and sensory disturbance in his lower limbs. MR imaging of his brain showed high signal intensity lesions on T2 imaging. IMP-SPECT images of the brain showed diffuse reduction of radioisotope uptake. Many skin rashes that looked like senile hemangioma were observed on his body. Several of those were biopsied, and the diagnosis of intravascular large B-cell lymphoma was made because of malignant B lymphocytes filling the vessel lumens in one of the seven biopsy specimens. CHOP therapy was performed and found to be effective for the neurological disorders such as dementia, paraplegia, and sensory disturbance. Our case suggests that skin biopsy for more than one sample of the skin rashes is very important for the diagnosis of intravascular large B-cell lymphoma. CHOP therapy might be effective in this case because of early diagnosis by skin biopsy.

Essential acrocyanosis (EA) present as a dusky discoloration of the hands as the sole symptom without any other abnormal results from laboratory investigation. Previously, the authors have found twisted collagen fibrils (TCF) in the normal skin of an EA patient. This study was intended to evaluate the significance of TCF in EA. Thirteen patients showing dusky discoloration were randomly selected and studied for TCF in normal skin by routine electron microscopy. TCF were found in 10 of 13 patients; 3 patients with only the discoloration (EA), 3 with the mild symptoms which were supposed to be Ehlers-Danlos syndrome (EDS), 1 with definite symptoms of EDS, 1 with Raynaud's disease and 2 with hyperglobulinemia. TCF were the ultrastructural sign for inherited malformation of collagen fibrils. EA was probably elucidated as a vascular disorder in TCF-carrying people. EA could be included in the disease category of EDS but it seems unreasonable to force EA patients into one of the subtypes of EDS. For pathogenesis, the inherited dysfunction in the hypertrophic pericytes of the subpapillary vascular plexus was presumed.

To explore the ultrastructure of elastic fibers in juvenile elastoma, three patients (two without osteopoikilosis and one under examination of bones and joints) were studied by routine electron microscopy. In addition to normal elastic fibers, all the patients also exhibited alterations in elastic fibers. The altered ultrastructures showed lucent, homogenous matrix without peripheral microfibrils. The homogenous matrix were seen in various extensions from the small protrusions of the normal elastic fibers to the complete replacement of the entire fibers. Collagen fibrils occasionally showed twisted figures. Normal shapes of dermal glycosaminoglycans were increased in number. It seems likely that the lucent, homogenous matrix without peripheral microfibrils are the characteristic changes of elastic fibers in juvenile elastoma. The alteration could be nevoid in nature.

The aim of this study, was to observe the effects of KH-1060, a new vitamin D3 analogue, on the dermis of hairless mice by electron microscopy. KH-1060 (0.2 micrograms/ml in isopropanol) or KH-1060 following betamethasone 17-valerate (2 mg/ml in isopropanol) was applied topically to the backs of hairless mice for 4 weeks. KH-1060 increased the number of dermal fibroblasts, the cytoplasm of which was dominated by secretory components. Mast cells contained normal mature granules and degranulated after disintegration. No extrusion of non-disintegrated granules was seen. Collagen fibrils were thickened and increased in number; however the content of type I collagen in the fibrils did not increase. Glycosaminoglycan figures appeared distinct. KH-1060 prevents betamethasone-induced changes in collagen fibrils and glycosaminoglycans, while no prevention was seen for mast cells.

Lipoid proteinosis (Urbach-Wiethe disease) is a rare, recessively inherited disorder that is characterized by the deposition of hyaline-like material in the skin, oral cavity, and other tissues. It usually appears in infancy with hoarseness. We report a case of lipoid proteinosis in a 10-year-old boy that demonstrates the characteristic clinical, histologic, and ultramicroscopic features of this disease.

Amyloid masses were found in the dermis of two brothers suffering from primary amyloidosis. The masses consisted of fibrils, composed in turn of twin hollow filaments of amyloid. An amyloid filament appeared as a 3 nm thick lucent core with a 2 nm thick wall. Occasionally 4--6 filaments were packed together in one fibril. The twin filaments were slightly twisted, with a twisting angle of 2.5 degrees and a coiling pitch of 1 160 nm. Wavy shapes of amyloid fibrils were also seen in elastic fibres. Amyloid fibrils were found in elastic fibres, under the basal lamina of the epidermis, sweat gland epithelium and Schwann cells; also around perineural cells, perivascular cells and, in one of the brothers, in collagen fibril bundles. No amyloid fibrils were found under the endothelial basal lamina. It would appear that amyloid fibrils are pathological fibrils belonging to the elastic fibre-basal lamina system.

A 5 1/2-year-old girl with idiopathic intestinal pseudo-obstruction became severely depleted of zinc during total parenteral nutrition and developed a vesico-bullous rash on face, hands and feet such as is seen in acrodermatitis enteropathica. Light and electron microscopy of a bullous lesion on one foot revealed a pronounced extracellular edema with cyst and cleft formation in the deep part of the epidermis. A few acantholytic cells were seen. In the electron microscope degenerate keratinocytes showed multiple vacuoles in the dark cytoplasm and slender, finger-like protrusions. Desmosomes were few. The basal lamina was well-preserved forming deep invaginations, which may serve to distinguish the condition from other bullous diseases of the skin.

Dermatological conditions characterized by dermo-epidermal separation, basal lamina discontinuity, multiplication, and thickness variability, and/or irregularity of the subepidermal space are discribed. Pathological changes of the dermo-epidermal junction are considered to be destructive or reproductive. Both may appear in combination. Destructive processes may be relfected by dermo-epidermal separation. Epidermal cells and/or dermal connective tissue appear degenerated. Thickening of the lamina may occur by reactive hyperproduction or by precipitation of pathological materials. Reproductive processes of the junction originate in the epidermal cells and are reflected in multilayering of the basal lamina. Interruption of the lamina and irregularity of the subepidermal space often precede these phenomena.

Vascular changes in morphea were studied in skin biopsies from 14 patients. Small vessels with pericytes present the changes in three different patterns. The first was the endothelial cells in a stimulated condition and thickened vascular wall with infiltrating macrophages and mast cells. The second was characterized by thick basal lamina of pericytes and the third by activated pericytes with infiltrating lymphocytes and plasma cells. Otherwise, all patterns showed altered endothelial cells and infiltrating macrophages and mast cells similar to the first pattern. The first pattern was mostly found in uninvolved skin. The second and the third were found in the inflammatory and sclerotic areas. It seems, therefore, that activated pericytes are the most essential changes in vessels of morphea. Probably, muscular vessels are simply involved in the fibrotic process.

During cultivation, the collagen fibrils of skin explants are broken down. The cells of the explants participate in this resorption. The ultrastructure of the intracellular degradation of collagen fibrils of cultured human skin has been examined. Intracellular collagen fibrils occur in fibroblasts, macrophages, smooth muscle cells and unidentifiable cells. Normal collagen fibrils are engulfed and appear within membrane-bounded tubes of the cytoplasm. Primary lysosomes fuse with the tubes. Degraded intracellular collagen fibrils are frequently present in secondary lysosomes and show decreasing diameters, filamentous splitting, loss of axial periodicity, variable stainability and cross-banded filamentous aggregates. The changes in the intracellular collagen fibrils are identical with those seen in the extracellular space. The present study demonstrates that various cell types in dermis are involved in collagen fibril degradation and that the lysosomes play an important part in the intracellular resorption.

Filamentous aggregates of collagen are distinct structures in the pathological dermis. These aggregates are distinguishable from fibrous long-spacing collagen (in vitro and at biopsy) and the Luse body. The aggregates are produced from dermal collagen fibrils by clostridial collagenase and culture-medium extract, which supposedly contains cellular collagenase at a neutral pH, as well as by organ cultures. In vitro experiments showed that carrageenan granuloma contains fibrous long-spacing collagen and segment long-spacing collagen. The granuloma also contains the aggregates. The aggregates were found in skin biopsies from syphilitic chancres, acrosclerotic scleroderma, morphea, mycosis fungoides, myeloid leukemia, mastocytosis and malignant melanoma. These findings indicate that the aggregates are products of the in situ degradation of collagen fibrils by some collagenolytic factor. This factor may originate in fibroblast-like cells, reticulum cells, leukemia cells, mast cells and melanoma cells.

Routine electron microscopy was carried out on biopsy material taken in an active stage from cutaneous sarcoid granulomas of 5 patients. In addition, mononuclear cells isolated from the peripheral blood of 2 patients and 2 controls were studied prior to and after culture with phytohemagglutinin. The infiltrating cells of the sarcoid granulomas varied only slightly from patient to patient. The dominant cell types were macrophages and epithelioid cells rich in endoplasmic reticulum. Epithelioid cells with numerous secondary lysosomes were frequently seen. Typical as well as atypical lymphocytes, giant cells and epithelioid cells with many primary lysosomes were less frequent. No atypical lymphocytes were seen among the mononuclear cells from the peripheral blood, either before or after culture with phytohemagglutinin.

Five biopsies from three patients with localized myxedema were studied by electron microscopy. The dermis showed an overwhelming accumulation of microfibrils with knobs (acid glycosaminoglycans) and an amorphous material containing glycoprotein. Furthermore, evidence of degradation without new formation of collagen fibrils was found. Considerable numbers of mast cells with various types of granules, fibroblasts with dilated granular endoplasmic reticulum, and macrophages were seen in the mucinous areas.

Skin biopsies from thirteen patients suffering from Ehlers-Danlos syndrome, including 6 of the mitis type, 4 of the benign hypermobile type, one of the X-linked type, one of the ocular type and one of the periodontitis type, were studied by electron microscopy after routine preparation. Collagen fibrils showed a distorted arrangement of bent, curled or twisted fibrils and thread-like material. Similar changes may be seen in the skin of other hereditary disorders of connective tissue. However, abnormal collagen fibrils in normal skin suggests one of eight types of Ehlers-Danlos syndrome. Clinical variants cannot be differentiated on the basis of ultrastructural findings. Elastic fibres were normal without degenerative changes. Perineurium was lacking in dermal nerves of most patients. Fibroblast-like cells showed no cystic cisterna of endoplasmic reticula.

Dermal cells maintained in cultured human skin explants for up to 10 weeks were studied by electron microscopy. Common findings in the cell organelles were: 1) altered nuclear shapes and numerous nuclear bodies; 2) reduced rough endoplasmic reticulum; 3) a prominent Golgi complex; and 4) an increasing number of free ribosomes, mitochondria, glycogen granules, lysosomes and lipid droplets. The individual types of dermal cells showed various cytoplasmic changes according to duration of the culture. The fibroblasts displayed a moderately developed rough endoplasmic reticulum. The macrophages were filled up with lysosomes and residual bodies. The mast cells showed typical as well as atypical granules. The smooth muscle cells had a variable content of myofilaments. The pericytes and the smooth muscle cells, both surrounded by a basal lamina, became increasingly difficult to discern from each other as a consequence of the decreasing number of myofilaments in the latter. The endothelial cells were recognized because of the preserved blood vessel architecture. Besides the above-mentioned cell types, two other types appeared with the culture time. The unidentifiable cells were characterized by dense zones of the cell membrane and an adjacent extracellular basal lamina-like material. This cell type may be derived from the pericytes of the small blood vessels. The primitive cells had a large rounded nucleus and a cytoplasm with few organelles. This cell type is assumed to represent a precursor cell common to various cell types.

A case of pseudo-Kaposi sarcoma of the feet (acroangiodermatitis) is reported. The patient showed clinical and light-microscopic signs closely resembling Kaposi's sarcoma, but by electron microscopy of skin biopsies definite signs of degeneration of vascular walls and infiltrating cells were demonstrated. Electron microscopy should be applied when conventional histology is inconclusive or fits poorly to the anamnestic information and/or clinical appearance of the lesions.

Clostridial collagenase, elastase, medium material of human skin culture, dithioerythritol and citrate buffer, pH 3.5, were applied to fresh human skin specimens. Phenomena of degradation of dermal fibrils were observed by electron microscopy.

Thirty-nine peripheral nerves in dermis of 12 morphea patients were analysed for ultrastructural changes. Changes found in the mesenchymal parts of the nerves, i.e. epi-, peri- and endoneurium, were myxedematous changes, collagen fibril degradation, cell infiltration and abnormal fibrosis. The infiltrating cells were lymphocytes and plasma cells as well as mast cells and myofibroblast. Perineural cells were assumed to be one of the origins of myofibroblasts. The axons and the Schwann cells showed slight signs of degeneration.

Punch biopsies from syphilitic leukoderma lesions and from unaffected skin in 3 patients with secondary syphilis were studies in the transmission electron microscope. In one of the patients the pigment disorder was not preceded by any visible syphilids, and in the biopsy from the leukodermal skin in this patient Treponemata pallidium were demonstrated around vessels and inside nerve fibres in which the myelin sheaths of the axons showed evidence of degeneration. In the other 2 patients the depigmented areas appeared while macular and papular syphilitic lesions were healing. In the biopsies from the leukodermal lesions of these 2 patients and from unaffected skin of all 3 patients, no treponemes were demonstrated. The study indicates that syphilitic leukoderma is not invariably a post-inflammatory phenomenon, but the pigmented skin lesions may themselves represent stigmata of an active syphilitic infection.

Adenyl cyclase activity in normal human epidermis was detected by an electron microscopic cytochemical technique. The sodium fluoride sensitive receptors were demonstrated on the outer sheath of the cell membranes. Adenyl cyclase activity was demonstrated in the basal cells and in the 4-5 lower layers of the Malpighian cells, while the superficial layers, stratum granulosum and stratum corneum showed no activity. The findings confirm and extend previous biochemical studies and provide a clue to the conception of the adenyl cyclase enzyme as a transmembrane arranged system.

A young female with local panatrophy of the right-side extremities affecting all mesodermal layers--dermis, subcutaneous tissue, muscles, and bone--is described. The atrophies were strictly linear. Ultrastructurally, collagen fibrils of the reticular dermis from the atrophic area consisted of two types, a large population of fibrils with decreased diameter and round cut-surface, and a small population with increased diameter and a "flower-like" cut-surface. Collagen analysis revealed a reduced hydroxyproline concentration and content per mm2 skin in atrophic area as compared with the perilesional and regional control. Urinary excretion of hydroxyproline was normal. Glycosaminoglycan analysis showed a less reduced content of hexosamine and uronic acid in the atrophic area per mm2 skin, but no differences in the concentrations. Consistently, the gel/fibre ratio (uronic acid/hydroxyproline) was found slightly elevated in atrophic skin. The proportions of the individual glycosaminoglycans heparin, dermatan sulphate, hyaluronic acid and chondroitin sulphates were not affected. It is concluded that reduced collagen and ultrastructural changes of collagen fibrils are significant features in local panatrophy. The significance of local foetal factors affecting the somatic mesoderm is discussed.

The dimensions of desmosomes and hemidesmosomes in normal human epidermis, i.e. their length and thickness, were studied in ordinary ultrathin sections. The length of desmosomes in the inner and middle squamous cell layer was 310 nm and 300 nm, while the thickness was 31 nm and 30 nm, respectively. In the outer squamous cell layer the values increased to 340 nm and 35 nm, respectively. The percentage total desmosomal length in relation to the perimeter of a cell showed the same tendency.

Salpeter-induced calcium deposits in ten patients showed a close clinical and histopathological similarity to the lesions of pseudoxanthoma elasticum. By electron microscopy and selected area diffraction analyses of the calcium deposits we find the changes indistinguishable from the changes previously described in involved skin of patients suffering from PXE. Clinically our patients were compared with the fourteen patients with traumatic calcification previously described.

The ultrastructure of dermal connective tissue in two patients suffering from fibrodysplasia ossificans progressiva (syn myositis o.p.) was studied. The disorder starts with soft tissue swelling which subsequently ossify. The connective tissue of various organs may be affected. No defects in calcium metabolism have been discovered. It was intended to study the primary event which initiates the ossification. The present ultrastructural study demonstrates an accumulation of proteoglycan microfibrils as well as glycoprotein material in dermal connective tissue. Both substances are prerequisites of calcification resulting from the binding of calcium and phosphorus ions. A subsequent release of proteolytic enzymes in the tissues may be set free the bound iones and, thus, initiate mineralization.

Skin biopsy specimens from a 60-year-old patient with paraproteinemia and generalized changes of the skin typical of scleromyxedema were studied with the electron microscope. The dermis was dominated by collagen fibrils and accumulations of peculiar connective tissue cells, while elastic tissue was sparse and in some areas completely absent. Large, sharply demarcated areas of a filamentous material were occasionally observed. The collagen fibrils were often surrounded by thin filaments with a periodic segmentation and by many glycosaminoglycan (mucopolysaccharide) filaments. The elastic fibres contained large amounts of elastic fibrils and small amounts of a homogenous matrix. The cytoplasm of the above-mentioned cells was dominated by lysosomes in different stages of development, often occupying almost all the cytoplasmic area. The collagen fibrils were found in close relation to these cells, frequently inside invaginations of the cells. Furthermore, collagen fibrils were observed free in the cytoplasmic area and inside the lysosomes, indicating lysosomal degradation of collagen.

Secretion of type IV collagen by keratinocytes was studied by anti-type IV collagen immunoglobulin in pure keratinocyte culture of the human adult. The cultivated keratinocytes secreted type IV collagen into the space between the cell growth and the underlying fixed film of human skin collagen type I. The secreted collagen was accumulated on the cell surface to form junction structures.

To obtain viable cells from normal human skin, clostridial collagenase was used. Crude collagenase digestion of collagen fibres and basal lamina results in free dermal cells and sheets of epidermis. The collagenase was tested at various concentrations, solvents and incubation periods. The specimens digested were either split or full thickness skin of varying size. The optimal result was obtained by using small (3mm across) split skin pieces incubated in 2 mg/ml collagenase. The choice of solvent MEM, MEM supplemented with serum, and Tris buffer, was less important. 3 hours' incubation the epidermis was peeled off in sheets and finally dissociated by trypsin-EDTA. The corium was completely digested after 6 hours. After 6 hours' incubation no viable cells could be seen. The epidermal cells appeared mainly as polygonal cells of various sizes and a few little dendritic cells. The dermal cells had a heterogeneous morphology during the first weeks of cultivation. After 2 weeks the cells appeared as fibroblast-like cells.

Biopsies from a 5-year-old girl with dermatomyositis and universal calcinosis were studied histopathologically and by means of electron optical techniques. The dermis was infiltrated by fibroblasts, lymphocytes and plasma cells. In the lower part of the dermis, dense basophilic areas were present. In the vicinity of these areas irregular elastic fibers appeared. In the electron microscope these elastic fibers appeared mineralized to varying degrees. The mineral part was identified as calcium apatite (either calcium-hydroxy-apatite or calcium fluoroapatite) by X-ray microanalysis and selected area diffraction. No calcification was observed outside the elastic fibers.

To obtain pure culture of epidermal cells from small human biopsies, two different techniques were tested and compared, i.e. separation of epidermis from corium before cultivation by trypsin and suction, and after cultivation by trypsin and collagenase. The most active growth of epidermal cells was obtained by the third technique, since short-term trypsin treatment released only fibroblasts from the culture. Crude collagenase (type I) was less effective than trypsin. Collagenase type II, III and IV had no effect on fibroblast release. Neither trypsin nor collagenases dispersed epidermal cells.

Primary cultures of epidermal cells from human adult skin were dissociated by dithiothreitol (DTT) with subsequent trypsinization. After treatment with disulfide reducing agents, the desmosomes were either destroyed or showed a homogeneous ultrastructure. Trypsin separated the homogeneous desmosomes, whereas cell membranes, organelles, and nuclei remained undamaged. Trypsin did not influence normal desmosomes. A suspension of human epidermal cells was recultivated in new flasks. Two types of cells grew in the cultures--polygonal and spindle-shaped. The polygonal cells were maintained for 30 to 60 days and grew slowly. The spindle-shaped cells were leucine-amino-peptidase negative, grew actively, and were subcultured.

Collagenolytic enzymes are produced by cultured skin explants. During cultivation the acellular compartment of the dermal connective tissues is digested away. The ultrastructure of the connective tissue resorption has been studied in human skin maintained in organ culture for 2--10 weeks. The connective tissue changes are: (1) Collagen fibrils with normal axial periodicity but decreasing diameters. On cross sections these fibrils have irregular outlines, while the longitudinal sections show fibrils separated into thin bundles of filaments 40--80 A thick with preserved normal axial periodicity. (2) Cross-banded filamentous aggregations (CBFA) consisting of fine parallel filaments 25 A thick and without axial periodicity. The CBFA has 350 A thick bands at 525 A intervals. At the end of the cultivation, the CBFA are replaced by solitary filaments 25 A thick. (3) The elastic fibres show no marked changes of the amorphous matrix, while the fibrils disappear. The loss of collagen and elastic fibrils during cultivation of the skin gives direct evidence of connective tissue degradation. The described changes are discussed in relation to previous ultrastructural studies on connective tissue resorption of various tissues.