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At least 19 recordsLinked to original sources
PubMed1978

Parakeratosis in some epidermal tumors: fine structural and immunohistochemical similarity between parakeratosis and "Hornmark" -like structure.

Both parakeratosis and "Hornmark" -like structure are basic histopathologic changes found in a variety of skin lesions. In order to investigate more closely the architecture and components of these two structures, three cases of epidermal tumor which showed both parakeratosis and "Hornmark" -like structure were studied by using routine histology and histochemistry, immunofluorescence technique, and electron microscopy. In the intercellular space of the stratum corneum in these two structures, diastase-resistant PAS-positive substance was found. This substance also showed positive immunofluorescence for immunoglobulins, complement, and fibrinogen. Electron microscopically, this substance was moderately electron-dense and fine granular, and was located in the intercellular space and in part in the cytoplasm of the horny cells. On the basis of these findings, this substance was judged more likely to be derived from the components of plasma protein than a result of the degeneration of epidermal cells. Only quantitative difference was observed between these two structure. This substance was considered to play an important role on the increased cohesiveness of the horny cells. However, whether this is a product of antigen-antibody reactions, or the result of the process similar to blood coagulation, remains to be elucidated.

Aged↗
PubMed1992

[Considerations of the pathogenesis of parakeratosis variegata based on morphologic and molecular genetic findings].

We report on a 63-year-old woman who had been suffering from generalized parakeratosis variegata since she was 7 years old. Increased tightness of the skin was the only clinical symptom. On the whole integument except for the face, we found a fine network of hyper- and depigmentation and telangiectasias. The skin surface was dry and atrophic with fine lamellar scaling. Histological, immunohistological and ultrastructural findings indicated early infiltration by a cutaneous T-cell lymphoma. However, PCR analysis of the T-cell receptor gamma-chain genes revealed multiple amplification products favouring a polyclonal T-cell proliferation. In light of the clinical history over a period of 56 years, we consider parakeratosis variegata to be a benign, chronic inflammatory condition, as is confirmed by the results of PCR analysis in this patient.

Diagnosis, Differential↗
PubMed1992

[Symptoms and course of a parakeratosis outbreak in a boar raising facility].

A case of parakeratosis in pigs due to secondary zinc deficiency (zinc/calcium ratio 0.4 g/100 g; 68.7 mg zinc, 17.1 g calcium per kg food) is reported. Morbidity and symptoms were much more marked in growing boars than in female animals of the same age. In sows the disorder appeared ten days after the first symptoms were seen in the boars. Adult breeding pigs developed no signs of parakeratosis.

Animals↗
PubMed1992

Dietary fibre in the diet of the growing pig: effects on apparent digestibility and resultant implications for its use in reducing the incidence of oesophagogastric parakeratosis.

The effects on apparent digestibility of increasing dietary fibre concentrations in barley-based diets by substituting for barley either bran, oatmeal by-product, guar gum or pectin were studied using 72 pigs. Increasing substitutions of bran up to a maximum of 300 g kg-1 gave progressive decreases in apparent digestibility of dry matter, ether extract and gross energy fractions and in digestible and metabolisable energy contents, progressive increases in apparent digestibility of modified acid detergent fibre but had no consistent effect on either nitrogen or extract free of nitrogen fractions. Increasing substitution of oatmeal by-product up to the same maximum gave significant linear decreases in apparent digestibility of dry matter, extract free of nitrogen and gross energy, significant depressions in apparent digestibility of modified acid detergent fibre and significant increases in ether extract. Guar gum and pectin, both substituted to a maximum of 50 g kg-1 had no significant effects on apparent digestibility. The results are discussed in the context of the concentrations of dietary fibre needed to reduce the incidence of oesophagogastric parakeratosis.

Animal Feed↗
PubMed1975

Cytological and histological keratinization studies in leukoplakias of the mouth.

A correlative histocytological study for keratinization was done in 446 cases of oral leukoplakia. Cytologically, keratinization could be correctly identified in 91% of leukoplakias exhibiting orthokeratosis, 73% of leukoplakias exhibiting parakeratosis, and 78% of cases showing both types of keratinization. Cytologically, orthokeratosis was present in 83% of individuals with homogeneous leukoplakia and in 69% with ulcerated leukoplakia, while parakeratosis was present in 7% of homogeneous leukoplakias and in 19% of ulcerated leukoplakias. A higher frequency of dysplasia was observed in smears and their corresponding histological sections for those cases which had revealed only parakeratosis in the cytological examination and for both orthokeratosis and parakeratosis as compared to those showing only orthokeratosis. It is suggested that the cytological method is a reliable method for studying oral keratinization and is of value to the clinician in identifying the type of leukoplakias which may need to be biopsied for further surveillance.

Cytoplasmic Granules↗
PubMed1977

The effects of feeding a zinc-deficient diet on taste acuity and tongue epithelium in rats.

Taste preferences, fluid intake and histology of tongue epithelium were studied in rats fed a zinc-deficient diet and in pair-fed controls. The results of two-bottle preference tests demonstrated that zinc-deficient rats exhibited significantly increased preferences for 1.5 X 10(-1) M HCL and 1.28 X 10(-6) M quinine sulfate as well as a significant increase in relative fluid volume intake. Histologic examination of the tongue epithelium of the zinc-deficient rats showed a hypercellular prickle cell layer and a marked parakeratosis. The fungiform papillae of the zinc-deficient rats exhibited acanthosis and mild parakeratosis. However, the pore region of the taste buds did not seem to be covered by the parakeratotic epithelium. The results suggest that the impaired taste observed in zinc-deficient rats may not be related to blockage of tastants from the pore region.

Animals↗
PubMed1977

Ultrastructure of the contrasting types of keratinization seen in the tail epidermis of the laboratory mouse Mus musculus.

The mouse tail epidermis undergoes contrasting forms of keratinization. Around the hair follicle there is a granular layer containing keratohyalin granules, and nuclei are absent from the horny layer. In the scale regions keratohyalin is not formed and nuclear remnants are retained in the horny cells as in parakeratosis generally. These findings from light microscopy were confirmed by transmission electron microscopy. The complete breakdown of organelles in the follicular regions contrastred with the retention of effete nuclei in the scales. Some of these nuclear remnants were pyknotic as in abnormal human parakeratosis, but most were further degraded with loss of nuclear membranes. In the boundary zone between the follicular and scale regions the epidermal cells had a few small keratohyalin granules and also showed incomplete degradation of nuclear remnants in the horny cells. The change from living epidermal cells to dead keratinized cells was abrupt in both the follicular and scale regions. In both sites the plasma membranes of the horny cells were thickened and there was a cytoplasmic meshwork of microfibrils in the cells.

Animals↗
PubMed1979

Evolution, maturation, and regression of lesions of psoriasis. New observations and correlation of clinical and histologic findings.

The evolution, maturation, and regression of lesions of psoriasis were studied histologically. The earliest histologic changes in pinhead-sized macules of psoriasis consist of a superficial perivascular infiltrate of lymphocytes and histiocytes and dilation and tortuosity of the blood vessels in the dermal papillae. Some lymphocytes move upward into the spinous zone of the epidermis and slight intercellular edema develops. Above these slight spongiotic foci, and after the granular layer disappears, the cornified layer becomes compact, and parakeratosis and epidermal hyperplasia develop. Only then do neutropils move through the epidermis into the mounds of parakeratosis. These changes, initially focal and episodic, become more confluent and constant, resulting in formation of clinical plaques. In spontaneously resolving lesions, inflammatory cells disappear first, the other changes next, and tortuosity of blood vessels in the dermal papillae last.

Capillaries↗
PubMed1978

Epidermal differentiation in normal and growth-retarded infants: studies in two animal models and in human babies.

The influence of prenatal growth retardation on epidermal growth and keratinization was studied in small-for-dates human babies, runt piglets and in rat fetuses subject to maternal protein deprivation. In the human babies and rat fetuses growth retardation was associated with reduced epidermal growth but normal patterns of differentiation were present. Thus, epidermal thickness was less and keratinizing zones narrower than seen in normal weight individuals. In the runt (small-for-dates) piglet, epidermal development differed from that seen in normal weight piglets of the same gestational age and from that seen in the human and rat. The epidermis was thicker with a negligible stratum granulosum and with the stratum corneum containing nucleated cells, a condition resembling 'parakeratosis'. This pattern was less often seen in normal weight piglets. Differences between the skins of the three speecies studied at a perinatal stage may be related to clear dissimilarities which exist in the tissues later. Parakeratosis as a transitory phase in the development of pig skin is probably related to a higher rate of epidermal keratinization in this species than occurs in either human babies or rat fetuses.

Animals↗
PubMed1977

The keratinization disorder in collodion babies evolving into lamellar ichthyosis. Its possible relevance for determining the primary defect in lamellar ichthyosis.

Two collodion baby girls with disorder evolving into lamellar ichthyosis were followed by light and electron microscopy. Light microscopically, the neonatal colloidion skin was characterized by a thick compact stratum corneum which was PAS positive in its upper two thirds, by a thin stratum granulosum and by a non-acanthotic stratum spinosum with normal mitotic activity. Electron microscopically, the upper stratum corneum appeared pathological, whereas the lower part was normal except for some minor parakeratosis. The main alterations in the underlying stratum granulosum were diminished tonofibrils and keratohyalin. Biopsy specimens taken at the age of 2 weeks were typical for lamellar ichthyosis and showed hyperkeratosis with focal parakeratosis, a thickened stratum granulosum in which the cellular content of keratohyalin and tonofibrils was moderately diminished, and acanthosis with increased mitotic activity. It appears that the ultrastructural changes of the stratum granulosum, seen in lamellar ichthyosis, are already present in the collodion skin of the newborn, at a time when the epidermis does not yet show an increase in mitotic activity.

Female↗
PubMed1979

Evaluation of carcinogenic effect of mineral oil used in the processing of jute fibres.

To evaluate the carcinogenic activity of jute-batching oil (JBO), this substance was painted on the skin of ITRC mice up to 300 days. Initially hyper- and parakeratosis of the stratum corneum, acanthosis and spongiosis of the stratum Malpighii, hyperactivity of fibroblasts, and laying down of collagen fibres in the dermis were encountered at 100 days. This was followed by poor hair growth, acne formation and ulceration. As time passed, these animals partially adapted themselves to the oil-painting so that by 200 days hyperkeratosis and parakeratosis of the stratum corneum, as well as acanthosis and spongiosis of the stratum Malpighii, had almost disappeared. The ulcers healed and no more acne was visible; however, the baldness and loss of hair appendages persisted to 300 days. No carcinogenic changes in the skin or in the viscera of these mice were observed. On UV and IR spectroscopy no traces of any polycyclic aromatic hydrocarbons were found in the JBO sample. Mice, on the other hand, when painted with the known carcinogen 3,4 benzpyrene (BP), developed skin tumours, showing that the mice used in this study were not cancer-resistant. Also, when JBO was applied with BP, the time taken for tumour development in mice was shortened by about 4 weeks as compared to another group painted with the same dose of BP alone. This suggests a cancer-promoting activity which needs to be investigated further.

Acne Vulgaris↗