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Biomedical subjects

W Montagna

Publications and source records attributed to W Montagna.

At least 19 recordsLinked to original sources
PubMed1991

The architecture of black and white facial skin.

This study yielded the following findings on the morphologic facial skin differences between black and white women: The epidermis of black skin has more and larger singly distributed melanosomes in the keratinocytes and corneocytes than that of white skin. The stratum lucidum in black skin is not altered by sunlight exposure. The epidermis of black skin rarely shows atrophied areas. The elaunin and oxytalan fibers in black skin are not disposed in candelabra-like formations. Black skin has minimal elastosis and elastic fibers stain pink or red with the hematoxylin and Lee procedure; none stain lilac or blue. The dermis of black skin contains many more fiber fragments composed of collagen fibrils and glycoproteins. Fibroblasts are more numerous, larger, have more biosynthetic organelles than white skin, and are often binucleated and multinucleated. The dermis of black skin has many binucleated and multinucleated macrophages and multinucleated giant cells. Black skin has many more mixed apocrine-eccrine sweat glands than does white skin and more blood and lymphatic vessels.

Adult↗
PubMed1991

Age, sunlight, and facial skin: a histologic and quantitative study.

Quantitative methods were developed to assess the interrelation between age and sunlight on the facial skin of healthy women living in the same sunny area. The women were grouped into the following categories: young versus old and low versus high solar exposure. The features evaluated were perceived age, amount of facial wrinkling, skin color, and skin elasticity. A punch biopsy specimen of cheek skin was obtained and prepared histologically for evaluation of solar elastosis. The histologic examination was complemented by quantification of collagen and elastin by computer-assessed image analysis. Perceived age was estimated by untrained women viewing high quality photographs. As expected, those with greater sun exposure looked older and had more wrinkles, more severe elastosis, increased elastin, and decreased collagen.

Adult↗
PubMed1990

Structural changes in ageing skin.

As average life expectancy is increasing, the ageing of skin presents a growing problem for dermatologists. When considering ageing it is important to distinguish between the effects of true biological ageing and environmental factors, such as exposure to sun. Epidermal changes associated with ageing involve the flattening of its underside, a reduction in the number of Langerhans cells and of melanocytes, and a decline in the number of melanosomes synthesized, leading to reduced pigmentation. Dermal changes involve a reduction in the collagenous and elastic fibres, fibroblasts, mast cells and macrophages, and dilation of the lymphatic channels. The number of hair follicles declines with age, but their structure remains unchanged. Ageing does not affect the sebaceous glands, but some changes occur in the exocrine sweat glands.

Adult↗
PubMed1989

Histology of sun-damaged human skin.

In glycomethacrylate sections of sun-exposed skin, we found the epidermis a sensitive index of damage. The stratum corneum of severely damaged skin was often compact and laminated, or gelatinous, and sometimes contained vesicles full of proteinous material. These vesicles arose from the enlarged and distinctly cellular-thick stratum lucidum. Sometimes there was no clear transition between the stratum lucidum and corneum. In the malpighian layer, cell heterogeneity, vacuolization, dysplasia, and zonal necrosis were common. The number of Langerhans cells was reduced in sun-damaged epidermis. The dermis had the usual disparate degrees of elastotic changes, with the formation of amorphous masses and the occurrence of fiber breakdown (fibrorhexis and fibrolysis). Macrophages among the elastotic masses contained coarse granules. When stained by means of the hematoxylin and Lee technique, the elastotic masses in the papillary dermis were pink or red but those in the mid dermis stained lilac to blue; all other elastic fibers stained pink or red. We found reticulin fibers predominantly around the elastotic masses and in areas of fibrorhexis and/or fibrolysis; a delicate collagenous fiber scaffolding supported the elastotic masses.

Adult↗
PubMed1988

Wound healing in the sex skin of pig-tailed macaques.

We studied wound healing in methacrylate- and araldite-embedded sex skin, a unique tissue that embodies the properties of friction surface and hairy skin. The largely light-microscopic observations were supplemented with transmission electron microscopy. The time of epidermal bridging was directly dependent on how closely apposed were the wound margins. Repair in the dermis always occurred more rapidly in the upper and in the lower parts of the wound gap than in the middle. Early in healing, the original epidermis cut off a wedge of skin in the upper wound margin (precocious remodeling) and cast it off at the margin of the clot. Remodeling (collagen resorption) inside the wound gap is accomplished primarily by fibroclasts. All mast cells in the vicinity of the wound attain fatty vacuoles. Adipose tissue near the wound undergoes lipolysis: the adipocytes gradually become smaller and their cytoplasm reticulated as small fat vesicles are extruded in the interstitium; fibroblasts, macrophages, polymorphonuclear leukocytes (PMNs) and mast cells readily phagocytose the fat vesicles. Elastic fibers do not participate in wound healing. There was no evidence of elastic fiber formation in granulation tissue.

Animals↗
PubMed1987

Histological techniques for the study of granular cells during wound healing.

We have used GMA-embedded tissues sectioned 2-3 mu for the identification of granulated cells in wounded and normal macaque tissues. Mast cell granules stain brilliantly with Giemsa or with PAS counterstained with alcian blue, neutrophils stand out clearly when treated with the PAS method and macrophage granules stain with PAS as well as with basic dyes. These techniques are helpful for the identification of these cells during wound healing and during inflammatory processes.

Animals↗
PubMed1982

Reinnervation of hair follicle end organs and Meissner Corpuscles in skin grafts of Macaques.

Plugs of occipital hairy scalp and pieces of digital pads were transplanted to the frontal scalp of stump-tailed macaques (Macaca arctoides). Both types of grafts grew well and retained their original appearance for several years. We traced the regrowth and reinnervation of hair follicles and Meissner corpuscles in sequential biopsy specimens of these grafts. Two weeks after transplantation, hair follicles in the grafts appeared to have lost all integrity but began to regrow after 4 weeks. The nerve and organs of hair follicles began to reappear at 8 weeks. Thereafter, grafts with large terminal hairs remained viable in the host bald frontal scalp for as long as 8 yr. In the digital skin grafts, the cytoskeleton of the Meissner corpuscles could be distinguished after 4 weeks; after 8 weeks nerves from the host tissue could be traced to the end organs. Perivascular nerve plexuses and nerves to the piloerector muscles were clearly seen in both types of graft after 8 weeks.

Animals↗
PubMed1980

A reinvestigation of solar lentigines.

Solar lentigines were reinvestigated by a number of different methods to gain a better perspective on their structure. In histologic sections and dopa preparations of split skin, large numbers of melanocytes were seen crowded at the base of the clubbed, budding rete ridges. In split-skin preparations, the scanning electron microscope showed complex systems of ridges, columns, and craters on the underside of the lentiginous epidermis. Oval bodies measuring 15 to 30 mu, with dendrites, were numerous at the apices of the complex epidermal ridges; these bodies were presumed to be melanocytes. In transmission electron micrographs of lentigines, the melanosome complexes inside the keratinocytes were much larger than those found in noninvolved skin. The complex and distinctive architecture of these maculae is probably the result of concurrent proliferation of melanocytes and keratinocytes.

Aged↗
PubMed1979

Structural changes in aging human skin.

In both exposed and protected areas of progressively older people the underside of the epidermis becomes increasingly flattened out. This flattening is accompanied by a comparable rarefaction of the superficial blood vessels. In this article we review the architecture of the elastic fiber framework in the papillary dermis of skin protected from the sun; aging changes that occur are similar to, but less severe than, those in sun-exposed areas. Most cutaneous sensory end organs are little affected by aging; those in the external genitalia, however, and particularly those underneath the vaginal epithelium become smaller and some disappear.

Adolescent↗
PubMed1979

Aging model for unexposed human dermis.

Young human dermis is charterized by the presence of many fibroblasts with distended endoplasmic reticulum, extensive Golgi bodies, and orderly and "clean"-appearing groundwork. Older dermis contains inactive fibrocytes with lipofuscin-like granules, macrophages with dense granules, and extracellular spaces with evidence of degeneration. We have found the sex skin of cycling pigtail macaques (Macaca nemestrina) a predictable model for studies on aging changes in human dermis. Swollen sex skin has many biochemical and ultrastructural properties that are similar to those of young dermis, and deflated sex skin resembles older human skin. Sex skin, however, is unique in that it becomes "rejuvenated" with each succeeding ovarian cycle. This animal model may prove useful to researchers attempting to increase their understanding of aging in connective tissue.

Aged↗
PubMed1976

Catecholamine-containing nerve terminals in piloarrector muscles of stump-tailed macaques (Macaca arctoides) and the effects of local injection of 6-, and 5-hydroxydopamine.

The fluorescence histochemical method of Falck-Hillarp (62) demonstrates dense plexuses of catecholamine-containing nerves in the piloarrector muscles of adult stump-tailed macaques. When these muscle fibers are viewed under the electron microscope, most of the axon terminal profiles between them contain numerous dense-cored vesicles (adrenergic); the rest of the terminals contain mainly agranular vesicles (cholinergic). Intradermal injections of 6-hydroxydopamine (6-OHDA, 1 and 5 mg) or 5-hydroxydopamine (5-OHDA, 10mg) into the scalp caused the fluorescence from the nerve fibers in the muscles to completely disappear. The 6-OHDA injections induced severe degenerative changes in the adrenergic terminals whereas the 5-OHDA injections caused only the granules in the vesicles to increase in numbers. Thus, the piloarrector muscles of these macaques are innervated with both adrenergic and cholinergic terminals, but the former are more numerous than the latter.

Animals↗
PubMed1976

The skin of the giraffe.

The skin of the giraffe has the same general histological structure as that of other mammals, but there are notable features. The skin is heavily pigmented with the epidermis, pilary canals, and the outer cell layer of the apocrine duct richly melanized. Furthermore, melanotic dendritic cells are frequently found in the sebaceous glands, the entire length of the external root sheath, and the secretory tubules of the apocrine glands. The thick skin has a papillary dermis that extends to just beneath the secretory coils of the apocrine glands and bulbs of hair follicles and an equally thick reticular layer below these structures. The hair follicles do not grow in clusters, and with some regional variations, have associated sebaceous glands, apocrine glands, and arrectores pilorum muscles. Only the large hairs have a prominent medulla. In such specialized regions as the eyelids, nose, and lips, the apocrine glands are surrounded by cholinesterase-reactive nerves but the glands on the general body surface are not. The only specialized nerve receptors are hair follicle end organs found on every hair of the eyelids, nose, and lips, but only rarely elsewhere.

Animals↗
PubMed1976

Histology and cytochemistry of human skin. XXXVI. The nose and lips.

The skin of the nose is characterized by often conspicuously dilated openings of the ducts of many subaceous follicles. Histological sections are dominated by gigantic sebaceous follicles, but there are also numerous vellus hairs with small sebaceous glands. All hair follicles on the surface of the nose and in the vestibule are completely invested with nerve end organs. In the vestibule, the glabrous upper surface has intraepidermal nerves and a few mucocutaneous end organs. the vermillion zone of the lip, which seperates the skin of the external lip and the mucosa of the inner lip, is keratinizing glabrous epithelium, often with numerous sebaceous glands in the upperlip. The transitional area between the keratinizing epithelium of the vermillion and the nonkeratinizing epithelium of the labial mucosa is abundantly supplied with mucocutaneous end organs, with only a few in the labial mucosa. The mucoserous glands of the labial mucosa are richly innervated.

Adult↗