-The larvae of phyllobothriid cestode worms found in marine mammals have been classified as either "delphinii group" or "grimaldii group". The first group has been divided into 11 morphotypes by previous studies. However, these categories are vague and often overlap, as they were described from different host species within a wide geographical range. The goal of this study is to simplify the categorization of larval shape and size based on samples obtained from a single host species. Eleven Fraser's dolphin Lagenodelphis hosei Fraser, 1956 stranded on the coast of Uruguay in November 2001 and subsequently died. From these animals, 190 cysts of Phyllobothrium delphini (Bosc, 1802) were obtained from the perigenital blubber of one female and one male. The prevalence of P. delphini was 18.18%, density was 159.38 larvae/kg of perigenital blubber, mean intensity was 95 and mean abundance was 17.27. The following measurements were taken: total length (BL), width and thickness of cysts, neck length (NL), scolex length, scolex width, external diameter of the suckers, and the ratio BL/ NL. In order to facilitate further identification of these phyllobothriid cysts, they were grouped into three categories according to shape and size: category "A" (22.35%, neck always straight); category "B" (62.35%, all with curved neck); category "C" (15.30%, U-shaped or with projections from the wall of the cyst, also curved neck). These morphological differences could correlate to time spent in the host. One other larval form (Tetrabothrius sp.) was also found in the blubber of these dolphins.Resumen -Las larvas de filobotridios en mamíferos marinos fueron clasificadas como "grupo delphinii" y "grupo grimaldii". En estudios previos el primer grupo fue dividido en 11 morfotipos. Sin embargo, estas categorías son vagas y a menudo se solapan, ya que fueron descritas a partir de diferentes especies de hospedadores provenientes de una amplia distribución geográfica. El objetivo de este estudio es simplificar la categorización de tamaños y formas larvarias a partir de una muestra obtenida de un único hospedador. Se estudiaron once ejemplares muertos de Lagenodelphis hosei Fraser 1956 varados en la costa de Uruguay en noviembre de 2001. Ciento noventa quistes de Phyllobothrium delphini (Bosc, 1802) fueron obtenidas de la grasa perigenital de una hembra y un macho. La prevalencia de P. delphini fue del 18.18%, la densidad 159.38 larvas/kg de grasa perigenital, la intensidad media 95 y la abundancia media 17.27. Se tomaron las siguientes medidas: largo total (BL), ancho y grosor del quiste, largo del cuello (NL), largo del scolex, ancho del scolex, diámetro externo de las ventosas y el cociente BL/NL. Para facilitar futuras identificaciones, estas larvas filobotrídeas fueron agrupadas en tres categorías de acuerdo a su tamaño y forma: categoría "A" (22.35%, cuello siempre recto); categoría "B" (62.35%, todas con cuello curvado) y categoría "C" (15.30%, cuello curvado, quistes en forma de U o con proyecciones de la pared). Estas diferen...

RESUMO.-[Clareamento da melanina na epiderme do Lobo-marinho-sul-americano e sua aplicação na imunohistoquímica enzimática.] O Lobo-marinho-sul-americano (Arctocephalus australis) é um mamífero marinho anfíbio distribuído ao longo da Costa do Atlântico e do Pacífico da América do Sul. Esta espécie está bem adaptada a diferentes habitats devido à morfologia dos membros em forma de nadadeira e de seu sistema tegumentar. Estudos imuno-histoquímicos são importantes para avaliar os mecanismos de adaptação da pele devido a diferencial expressão dos antígenos presentes no tecido dependendo da região da superfície corporal. Entretanto, sua epiderme altamente pigmentada (melanina) impede a visualização dos marcadores cromógenos utilizados na imunohistoquímica. Neste trabalho foi desenvolvido um método de clarear a melanina para permitir a visualização dos cromógenos sem alterar a afinidade antígeno-anticorpo para a imuno-histoquímica. A análise do índice do PCNA (proliferating cell nuclear antigen) na epiderme de A. australis, com diaminobenzidina (DAB) como cromógeno foi usada para testar o método. O clareamento da melanina permitiu obter o índice de proliferação celular na epiderme e evitar resultados falso-positivos sem afetar os resultados imuno-histoquímicos. The South American fur seal (Arctocephalus australis) is an amphibious marine mammal distributed along the Atlantic and Pacific coasts of South America. The species is well adjusted to different habitats due to the morphology of its fin-like members and due to some adaptations in their integumentary system. Immunohistochemical studies are very important to evaluate the mechanisms of skin adaptation due the differential expression of the antigens present in the tissue depending of the region of the body surface. However, its strongly pigmented (melanin) epidermis prevents the visualization of the immunohistochemical chromogens markers. In this study a melanin bleaching method was developed aimed to allow the visualization of the chromogens without interfering in the antigen-antibody affinity for immunohistochemistry. The analysis of PCNA (proliferating cell nuclear antigen) index in the epidermis of A. australis by immunohistochemistry with diaminobenzidine (DAB) as chromogen was used to test the method. The bleaching of the melanin allowed to obtain the cell proliferation index in epidermis and to avoid false positive results without affecting the immunohistochemical results.

The skin of the South American fur seal (Arctocephalus australis) is important for animal thermoregulation in both terrestrial and aquatic environments. Skin tissue samples were collected from A. australis for microscopic analysis and were related to anatomical references. The aim of this study was to describe the skin morphology, as well as to suggest the major anatomical regions and skin components involved in the thermoregulation of this species. Using light microscopy, the skin of six animals was examined based on histological, morphometric, and immunohistochemical criteria. Hair follicle morphology was examined using scanning electron microscopy. The skin was classified as either thick or thin based on its epidermal thickness. The thin epidermis regions had more abundant hair follicles, as well as high pigmentation, whereas the thick epidermis regions had very pigmented epidermal layers. Pigmentation of hair and skin is fundamental for protection against ultraviolet rays; moreover, hair is important in preventing abrasion, and provides an insulating layer against the external environment, which can be much colder than body temperature. Furthermore, the dermis is well vascularized, especially the superficial dermis. All regions of the skin have adaptations for maintaining the animal's condition in both terrestrial and aquatic environments. Among the studied regions, the interdigital region from hindflipper showed important morphological characteristics related to thermoregulation, such as having an epidermis of intermediate thickness, a dermis with a small number of hairs, a large amount of blood vessels, and sweat glands with large lumens, indicating that heat exchange in this region may be faster.

No abstract