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The kinetics of collagen reprecipitation from solutions of salt-extracted calf dermis in the presence of small amounts of mucopolysaccharide and nucleic acids (0.005 per cent in the final reaction mixture) has been reported by Wood (1960). The present paper is a parallel study using the same materials, and describes the electron microscopic (EM) morphology of the collagen precipitates replicated after 24 hours at room temperature. Satisfactory, uncontaminated EM preparations were obtained which showed that all the deposits were fibrous and bore the 640 A cross-banding characteristic of collagen except some narrow, background fibrils 200 to 1000 A wide precipitated in the presence of heparin. These exhibited fine striations about 220 A apart. Chondroitin sulfate greatly increased the rate of precipitation to give a deposit of low optical density consisting of narrow, rigid, discrete fibrils resembling fresh dermis. In contrast, heparin prevented macroscopic gelation, delayed precipitation, and only produced a scanty deposit of abnormal, short, wide, striated tactoids and compound fibers of varying length. The control preparations and the deposits formed in the presence of hyaluronic acid were intermediate between these two extremes. Delayed precipitation was associated with a coarser deposit and aggregation of the fibrils. A duplicate series of deposits precipitated in the presence of RNA and DNA, together with their controls, were examined after (1/2), 1, 1(1/2), 3, 9, and 24 hours. One set employed an acetic extract of whole calf dermis and the other salt-extracted dermis. The presence of 0.005 per cent DNA in the reaction mixture markedly delayed collagen precipitation with the slow formation of abnormal, short, wide tactoids and compound fibers. RNA also interfered with the quantity and quality of the deposits which contained far less collagen resembling unfixed, normal, adult human dermis, than the controls at the corresponding time intervals. Comparison of the experiments employing whole calf dermis with those employing the salt-extracted material demonstrated that at every time interval in all the experiments the deposits were retarded when salt-extracted dermis was used. This suggests that the salt-soluble components of the dermis play a part in fiber formation.

This investigation has sought to determine the relation between collagen fiber and fibroblast during fibrogenesis. Toward this end the surfaces of chick fibroblasts grown under in vitro conditions have been examined with the electron microscope after fixation in OsO(4). Supplementary information has been obtained from thin sections of fibroblasts fixed in situ during phases of fiber production. The evidence provided by these studies and by various conditions of the experiments indicates that the unit fibrils of collagen form in close association with the cell surface. They were never observed within the cell. When these unit fibrils form in bundles it appears as though templates of some nature, possibly coinciding with stress fibers within the cell cortex, influence the polymerization of the fibrils out of material available at the cell surface. From here the fibrils and bundles of them are shed into the intercellular spaces and there grow to limited diameters by accretion of materials from the general milieu.

Graft of dermis is clinically and experimentally superior to graft of whole skin for use as reinforcement at the site of repair of hernia, for gross cysts do not form and it fuses better with the surrounding tissues than does whole skin. Placing either dermis or skin under tension helps prevent cyst formation and aids fusion with surrounding tissues. Dermal grafts are less liable to infection than are whole skin grafts, either at the time of operation or later.A split-split flap dermatome technique is presented as a preferred technique for obtaining a dermal graft from the thigh in cases of ventral hernia in which the abdominal skin is stretched, attenuated and inelastic because of the massive size of the hernia. This technique was used in 27 cases of massive hernia. There was infection in one case of the 27 and subsequent healing was satisfactory. One patient died of spontaneous rupture of an intracranial carotid aneurysm. Hernia did not recur in any patient.A split-split free graft dermatome technique is presented for use in cases in which an elliptical segment of normal skin can be removed adjacent to an inguinal or thoracic incision for repair of a hernia or other use. This technique was used in seven cases of inguinal hernia and in one of diaphragmatic hernia with satisfactory results.

The effect of desoxycorticosterone acetate (DCA) on the granulation tissue of healing and healed linear laparotomy wounds was studied in young adult male guinea pigs maintained on a complete diet and on a known intake of ascorbic acid. DCA induces the production of an excessive amount of granulation tissue, as evidenced by a relatively great number of fibroblasts and by a larger amount of ground substance. This effect was accompanied by a slight to moderate lag in the maturation process of both cellular and intercellular elements. These changes were observed when DCA administration was begun 5 days prior to operation, but were less obvious or absent if DCA was injected, beginning on the 5th or 10th postoperative day. The results indicate that the action of DCA on immature, proliferating connective tissue is marked, and is considerably less or absent when connective tissue elements have reached partial or almost complete maturity. The effect of DCA on connective tissue does not appear to rest on the basis of an altered nutritional status. Chemical and histochemical studies of the adrenals suggest that the action of DCA on connective tissue is probably mediated through a disturbance of adrenocortical function, namely an imbalance between hormones of the zona glomerulosa (excess of DCA) and those of the zona fasciculata (deficiency of glucocorticoids). The presence of changes in granulation tissue and the lack of them in mature resting connective tissue of DCA-treated guinea pigs confirm the view that a profound difference in the response mechanism exists between resting and actively proliferating connective tissue.

The total amount of neutral salt-extractible collagen in the skin of growing, suckling guinea pigs amounted to about 10 per cent of the total collagen of the dennis. This is roughly equivalent to a 1 to 2 day increment in dermal collagen incident to growth. Fourteen days of static weight maintained by limited caloric intake reduced the neutral salt-extractible collagen to very low levels. Following this period, 5 to 7 days of steady weight gain induced by ad lib. feeding was required to produce significant increases in this collagen fraction. Return to control levels occurred within 12 days of continuous growth. The amount of collagen extracted from the dermis of young guinea pigs with cold neutral salt solutions varied directly with growth rate (weight gain) and was greatly diminished after short periods of restricted caloric intake. Two days of fasting diminished the total extracted collagen by one-half. Three consecutive extractions with citrate buffer pH, 3.5, of the residues remaining after exhaustive saline extraction removed 40 per cent more collagen from the skins of actively growing animals than from those of animals fasted for 2 days. However, subsequent extraction of residues with dilute acetic acid equalized the total amount of collagen extracted at acid pH from the two groups. The viscosity of cold neutral extracts was unrelated to the concentrations of non-collagenous proteins and carbohydrates but varied directly with the collagen content.

Using standard osmium fixation and methacrylate embedding techniques, a study has been made of the melanocyte of human biopsy skin removed under general and local anaesthesia. Melanogenesis was easily observable in the melanocytes, but immature pigment granules were rarely seen in the Malpighian cells. The passage of melanin from melanocyte to Malpighian cell-cytocrine secretion-is thought to have been observed. Phagocytes near the dermal-epidermal junction seem to have their pigment granules in vacuoles, rather than surrounded directly by the cytoplasmic matrix as in the melanocytes. This, together with the failure to observe "effete" melanocytes, prompts the suggestion that the phagocytes are melanocytes which have migrated from the epidermis into the dermis. A melanin granule is shown with alternating dark and lighter transverse striations, concerning which structure little can at present be said.

The basement lamella under the epidermis of amphibian larvae shows a sub-microscopic architecture of remarkable geometric regularity: It consists of about twenty layers of ground substance in which cylindrical fibers (presumably collagenous) of about 500 Angström diameter are embedded parallel to one another, but with the fiber directions alternating by 90 degrees from layer to layer. The repair of this membrane after wounding was studied electronmicroscopically in ultrathin sections. The sequence of events is as follows: (1) Epidermal cells cover the wound exudate by migration. (2) Rather uniform fibers of small size (<200 A) appear in the space between the epidermal underside and the subjacent fibroblasts; these fibers are sparse and oriented at random. (3) Proceeding from the epidermal surface downward, a wave of organization spreads over this primitive fiber tangle, resulting in the fibers becoming (a) straightened; (b) oriented; (c) packed into the characteristic layered structure; and (d) brought up into the 500 A diameter class.

A granulated cell in human skin has an ultrastructure similar to that of chromaffin cells of the adrenal medulla. This cell is closely associated with unmyelinated axons and may be the site of peripheral store of noradrenaline.

The distribution of 3,3',4',5-tetrachlorosalicylanilide (TCSA), 3,4',5-tribromosalicylanilide (TBS). and 4'-monobromosalicylanilide (MBS) in skin following topical application at varying times was investigated in fluorescence microscopy in unfixed frozen sections. Analyses were carried out before and alter removal of ethanol-extractable materials. In normal guinea pigs. TCSA was detectable in the entire epidermis and dermis between 5 min and 7 days or longer after topical application. It was recognized in the horny layer even after 21 days. Fluorescence of TCSA in sections disappeared completely after ethanol extract ion, unless the application sites were irradiated with long-wave UV. When the sites to which TCSA had been applied were irradiated, only TCSA in the horny layer was not extractable with ethanol. Compared with TCSA. TBS did not easily penetrate the skin and revealed granular fluorescence in the horny layer which disappeared after ethanol extraction. Long-wave UV irradiation transformed the fluorescence into a hand-like appearance which was not ethanol-extractable. The fluorescence of MBS was detected even after extraction. In vitro irradiated TCSA and TBS were washed out of application sites with ethanol. [ABSTRACT FROM AUTHOR]

Previous observations on suction blisters have indicated that dermal epidermal adherence is of a viscous nature. However, very small pressure differences over the epidermis generally fail to produce blistering even over extended periods of time. This suggests that a second, nonviscous, element is involved in the adherence of epidermis and dermis. In the present study experiments with interrupted suction were performed. Results demonstrate a process of repair, or regeneration of the adherence, operating with a time constant of less than 1 hr. This process of repair may be described mathematically as an elastic component in the adherence, suggesting the involvement of elastic structures. A process of active reattachment originating from the epidermal cells could also account for the observations. We believe that failure of the repair mechanism, followed in turn by rupture of the viscous bond due to small local pressure differences, may he the cause of some types of experimental and clinical blistering. [ABSTRACT FROM AUTHOR]

Newborn mouse skin was separated into dermis and epidermis by four procedures, each of which was found to reduce the ability of both skin components to incorporate 14C-acetate into fatty acids. For comparison, skin was labeled with acetate under the same conditions prior to separation by each method. Distribution of polyunsaturated fatty acids was studied after separation of prelabeled skin by trypsin and collagenase. In epidermis both unlabeled and labeled fatty acids were concentrated in the trypsin-released cell. Results indicated that C22 polyunsaturated fatty acids are possibly not synthesized by skin, except 22:4ω6 which is a dermal product. Collagenase-released cells contain mainly saturated acids. Linoleic acid was the only C18 diene observed. The fatty acid composition of both epidermis and dermis depended on the enzymatic method used. [ABSTRACT FROM AUTHOR]

The sebaceous glands in man are aggregates of various-sized acini that empty into a duct. Glandular configuration is determined by the relative size of the glands in any given area and the number of other glands in the same area, that is by the amount of crowding they are subjected to and by the nature of the dermis in which they grow. Regardless of differences in size, shape, or position, their cellular morphology and sequence of differentiation are similar but not necessarily identical. Sebaceous differentiation is the orderly synthesis, segregation, and accumulation of lipid droplets which culminate in enlarged, misshapen cells that fragment to form sebum.

The value of HL-A antigens as genetic markers and epidemiologic tools in various disease states is becoming increasingly apparent. The antigens of the HL-A system (the major histocompatibility locus in man) are found on most human cells, especially the leukocytes and cells of the epidermis and the dermis. Associations have recently been found for HL-A antigens in psoriasis. atopic dermatitis, systemic lupus ervthematosus, dermatitis herpetiformis, pemphigus vulgaris,. and malignant melanoma of the skin; in several other diseases, associations with HL-A antigens are also probably present. Two possible mechanisms of association of HL-A with various diseases are (1) a close linkage between a gene governing immunologic responsiveness to a disease and HL-A genes, or (2) antigenic (chemical) cross-reaction between HL-A antigens and the etiologic agent (e.g.. streptococci or viral capsular antigen) associated with the disease. [ABSTRACT FROM AUTHOR]

The influence of skin temperature on dermal-epidermal adherence was investigated. The adherence was measured by eliciting suction blisters; blistering time was determined under controlled skin temperature. In the range of skin temperatures investigated (20°-43° C) the adherence decreases continuously with increasing temperature. Adherence is, approximately, an exponential function of temperature; an increase of skin temperature by 10° C decreases blistering time by a factor of about 4. This type of relationship supports the hypothesis that epidermis and dermis are connected by a viscous bond. The strong influence of skin temperature suggests that a high viscosity is involved. [ABSTRACT FROM AUTHOR]

A simple, rapid separation of epidermis from dermis was achieved following incubation of human of guinea-pig skin in one molar sodium bromide at 37°C for 30 min. the resulting epidermal sheets incubated at 37°C in 0.1 M phosphate buffer (pH 6.8) for 15 to 120 minutes with 5 &times 10-3 M dopa or for 120 to 240 minutes with a mixture of 5 ×-3 M tyrosine and 5 × 10-3 M ascorbic acid gave good dopa-tyrosinase and tyrosine-tyrosinase reactions. Melanocytes were readily visualized because new melanin formed within the cytoplasm. [ABSTRACT FROM AUTHOR]

Elucidation of the steps in the biosynthesis of unusual "histidine-rich" Protein in the epidermis of the newborn rat has been hampered by an inability to reconstruct an efficient epidermal system for synthesis of any protein in vitro. Inhibitory activities (e. g. RNase and proteolytic enzymes) associated with epidermal catalytic components and failure to obtain active epidermal polyribosomal fractions have provided the main difficulties. Epidermal polyribosomes which actively incorporate labeled amino acids in the presence of a "pH 5 enzyme" preparation from liver, have now been obtained from the newborn rat. The epidermis, free of dermis, is homogenized in 0.25 M sucrose containing 1% sodium deoxycholate, 25 mM KCI, 5 mM magnesium acetate, 0.4 mM dithiothreitol and 50 mM Tris buffer, pH 7.5. The homogenate is submitted to differential centrifugation and the postmitochondrial fraction is further purified by ultracentrifugation in sucrose density gradients to obtain the polyribosomal fraction. Electron microscopy and analytical ultracentrifugation confirm the identity and composition of the RNase-sensitive polyribosomal fraction. [ABSTRACT FROM AUTHOR]

Samples of normal dermis were collected from seven women and six men ranging in age from 17 to 81 years. The water content increased with age while the total lipid remained unchanged. The tissue was separated into fractions representing 'ground substance' (isotonic saline extract), cells (tryptic digest), and collagen (gelatin). Each fraction was analyzed for nitrogen, hydroxyproline, hexosamine and hexuronic acid. The amount of the saline extract changed little with age. The amount of both the trypsin and gelatin fractions decreased with age. None of the measured components could be related to the sex of the donor. The proteins of the isotonic saline extract were examined by cellulose acetate, disc and immunoelectrophoresis. Qualitatively, all fractions resembled the plasma proteins. The relative proportions of the proteins corresponded closely to those in the plasma. The hemaglobin content of the extract was less than one percent that expected if the proteins were present in whole blood. Most of the hyaluronate of the dermis was found in the ground substance. Dermatan sulfate predominated in the cellular and collagenous fractions. The age and sex of the donor could not be related to the concentration of any fraction. The residue resembled pure elastin in its appearance under the light microscope after staining with hematoxylin and eosin, Heidenhain's azan or aldehyde fuchsin; its ultrastructure after sonication; its nitrogen and hydroxyproline content; and its amino acid analysis. The amount increased three-fold between 20 and 80 years of age. [ABSTRACT FROM AUTHOR]

The intensity of nucleoside triphosphatase activity in the fiber cortex is bilaterally asymmetric in the bulb and suprabulbar region of wool follicles of Merino sheep. In most follicles the region of greater activity is on the concave side of the deflected bulb. The activity is associated with cell membranes and in the follicle bulb is more intense in that portion of the fiber cortex adjacent to the side of the dermal papilla on which the basal lumina is thickened. The region of greater activity coincides with the orthocortex of the fiber at the suprabulbar level. Cortical segmentation therefore originates in the proliferative zone of the follicle bulb and is revealed by the bilateral asymmetry in the intensity of the enzyme reaction. [ABSTRACT FROM AUTHOR]

The distribution of 2,4-dinitrophenyl (DNP-) groups in skin following surface application of 5 or 0.2 per cent solutions of 2,4-dinitrochlorobenzene (DNCB) in ethanol on the perioral or back skin of normal guinea pigs was investigated at varying times using an immunofluorescent method. It was demonstrated that DNCB penetrated through epidermis into dermis and then combined with the skin components within a few minutes after application. DNP-group were clearly demonstrated in the cytoplasm of the epidermal cells and also detected in the histiocytic cells of the upper dermis. In the specimens taken at 9 hours after application of a 5% solution of DNCB, neerosis of the epidermal cells was observed. The reparative process of epidermis first appeared in fifteen-hour lesions of the perioral skin or in two-day lesions of the back skin, and DNP-groups were not detected in the regenerating epidermis. In the three-day lesions of the perioral skin or the eleven-day lesions of the back skin, no fluorescent material was observed in either epidermis or dermis. In the fifteen-hour and one-day lesions taken from the perioral skin to which was applied 0.2% solution of DNCB, the cells in the lower rate became poorly stained with the fluorescent antiserum. DNP-group were detected only in the cornified outer part of epidermis in the two and three-day lesions and then disappeared in the five-day lesions. It is concluded that the disappearance of the greater part of DNP-groups conjugated with epidermal component may be ascribed to the shedding of the epidermis to exterior. [ABSTRACT FROM AUTHOR]