Diseño y fabricación de modelos impresos en 3D como complemento para las clases prácticas de histología médica / Design and manufacturing of 3D printed models as a complement for medical histology practical classes

RESUMEN: Tradicionalmente, la Histología se ha apoyado del análisis de preparaciones histológicas a través del microscopio para su enseñanza. En este sentido, uno de los principales obstáculos que enfrentan los estudiantes al analizar los tejidos, es extrapolar una imagen bidimensional a una estructura tridimensional (3D). La impresión 3D permite subsanar esta limitación, haciendo posible fabricar material docente, con las características requeridas con un alto grado de detalle y bajo costo. El objetivo de este trabajo fue diseñar y fabricar modelos impresos en 3D como complemento para las clases prácticas de Histología Médica. Se fabricaron modelos impresos en 3D de la ultraestructura de la barrera de filtración glomerular (BFG) en su estado normal y síndrome nefrótico. Además, se fabricó un modelo de la capa muscular del esófago humano dando énfasis a la disposición helicoidal de sus fibras musculares. Los modelos de epidermis permitieron identificar sus distintos estratos: estrato córneo, estrato granuloso, estrato espinoso, y estrato basal. Dentro los beneficios derivados de la impresión de modelos en 3D podemos destacar el bajo costo económico de su fabricación, alta reproducibilidad, bioseguridad, y potencial para favorecer el aprendizaje y la enseñanza de la Histología. No obstante, es necesario analizar la percepción y beneficio sobre el aprendizaje de los estudiantes derivados de la aplicación de los modelos mediante técnicas de evaluación cuantitativas y cualitativas.

SUMMARY: Traditionally, Histology has relied on the analysis of histological slides through the microscope for its teaching. In this sense, one of the main obstacles faced by students when analyzing tissues is to extrapolate a two-dimensional image to a three-dimensional (3D) structure. 3D printing makes it possible to overcome this limitation, making it possible to manufacture teaching material with the required characteristics with a high degree of detail and low cost. The objective of this work was to design and manufacture 3D printed models as a complement for the practical classes of Medical Histology. 3D printed models of the ultrastructure of the glomerular filtration barrier (GFB) in its normal state and nephrotic syndrome were fabricated. In addition, a model of the muscular layer of the human esophagus was fabricated emphasizing the helical arrangement of its muscle fibers. The epidermis models allowed the identification of its different layers: stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. Among the benefits derived from 3D printing of models, we can highlight the low economic cost of manufacturing, biosafety and potential to favor the learning and teaching of Histology. However, it is necessary to analyze the perception and benefit on student learning derived from the application of the models by means of quantitative and qualitative evaluation techniques.

Relación entre el patrón dactiloscópico epidérmico y dérmico / Relationship between the epidermal and the dermal dactyloscopic pattern

El método más utilizado en identificación humana es el dactiloscópico, que registra, analiza y coteja los tipos fundamentales y puntos característicos de las figuras presentes en el dactilograma, determinando el grado de coincidencia, entre un patrón de identidad dubitada y uno de identidad indubitada. Debido a los procesos que afectan la piel de cadáveres, como la putrefacción entre otros, se utilizan las técnicas necropapiloscópicas que ocupan los patrones dérmicos para la identificación humana. El objetivo del presente trabajo es comparar registros epidérmicos con dérmicos, y validar científicamente, este método de identificación (epidérmico - dérmico). Para ello se utilizaron 32 dedos de cadáveres de individuos chilenos, de ambos sexos y de entre 40 y 80 años. Para obtener el registro físico artificial epidérmico y dérmico se utilizó la técnica de obtención de impresiones necrodactilares y se comparó a través de la técnica de cotejo dactiloscópico. Estos procedimientos fueron realizados por peritos criminalísticos de Carabineros de Chile. Se logró evidenciar diferencias importantes entre epidermis y dermis en cuanto a cantidad y calidad de puntos característicos y presencia de líneas seniles. En relación a tipos fundamentales, se evidenció que en dermis es difícil la observación de tipos fundamentales (borrosos) pero no se encontró ningún dígito que presentara tipo fundamental diferente entre epidermis y dermis. También se constataron diferencias por sexo y edad. Finalmente se pudo evidenciar, que existe una relación morfológica semejante entre registros físicos artificiales de patrones papiloscópicos epidérmicos con dérmicos provenientes del mismo individuo. Esto permite utilizar los registros dérmicos para la identificación humana positiva. Los resultados de este trabajo son importantes al aportar evidencia científica para la identificación humana en base al patrón dactiloscópico dérmico.

The most used method in human identification is the dactyloscopy, which registers, analyzes and collates the fundamental types and characteristic points of figures present in the dactylogram determining the degree of coincidence, between a pattern of identity that is dubious, and one that is indubious. Due to the processes that affect the skin of corpses, such as putrefaction, the necropapiloscopy techniques that occupy the dermal patterns for human identification are used. The objective of the present work is to compare epidermal with dermal records and validate scientifically, this method of identification (epidermal - dermal). For this purpose, 32 cadaveric fingers of Chilean individuals, of both sexes and between 40 and 80 years were used. In order to obtain the epidermal and dermal artificial physical record, the technique of obtaining necrodactyle impressions was used and compared through of the technique of dactyloscopic comparison. These procedures were carried out by criminalistic experts of Carabineros de Chile. It was possible to show important differences between epidermis and dermis in terms of quantity and quality of characteristic points and presence of senile lines. In relation to fundamental types, it was evidenced that in the dermis it is difficult to observe fundamental types (blurred) but no digit was found that presented a different of fundamental type between epidermis and dermis. There were also differences by sex and age. Finally, it was possible to demonstrate that there is a similar morphological relationship between artificial physical records of epidermal papiloscopic patterns with dermal patterns from the same individual. This allows the use of dermal records for positive human identification. The results of this work are important in providing scientific evidence for human identification based on the dermal fingerprint pattern.

Skin extract from Rhamdia quelen (Siluriformes: Heptapteridae) does not promote stress in conspecifics

Chemical communication is widely used in aquatic environments, where visual or auditory signals may not be always effective. Fish of the superorder Ostariophysi are known to display epidermal cells (club cells) that produce and store alarm substances, which are released to the water when the skin is damaged. Responses to alarm substances range widely, between active searches for refuge to a complete stop in any locomotor activity. In this study a large number of binucleated club cells (average density of 11 cells /5m2) were histologically observed in the skin of the catfish Rhamdia quelen (known as jundia). Skin extract (2, 5, and 10% w/v) applied for 15 minutes to conspecifics elicited increase in swimming activity and in the area visited by the fish inside the tank. However, exposure to the epithelial alarm cue did not evoke any stress response: plasma osmolality, ions (sodium, chloride, magnesium, and potassium), glucose and cortisol remained unchanged. In conclusion, the conspecific alarm cue of the jundia induces behavioral responses but not an acute stress response upon short-term exposure, compatible with its role in fostering physical integrity without representing major stress activation. Considering that in the natural environment such stimuli must quickly disappear due to dilution and that rapid protection responses may be necessary upon the possibility of an approaching predator, a faster mechanism to assure survival may come into play, such as sympathetic nervous system activation. Comunicagco qummica i amplamente utilizada por animais que vivem em ambiente aquatico, onde sinais visuais e auditivos nem sempre sco facilmente identificados. Os Ostariophysi sco conhecidos por apresentarem cilulas club na epiderme, as quais produzem e estocam substbncia de alarme que sco liberadas para o ambiente quando a pele i lesionada. As respostas dos peixes a substbncia de alarme variam entre exploragco ativa por refzgios ati a parada completa de atividade locomotora. Neste estudo, grande nzmero de cilulas club binucleadas (densidade midia de 11 cilulas/5m2) foram histologicamente observadas na epiderme do jundia, Rhamdia quelen. Peixes expostos a extrato de pele de conspecmficos (2, 5, e 10% peso/vol) por 15 minutos apresentaram aumento da atividade locomotora e da area de dispersco. No entanto, essa exposigco nco promoveu nenhuma resposta de estresse - osmolalidade plasmatica, mons (ssdio, cloreto, magnisio e potassio), glicose e cortisol nco sofreram alteragco. Conclummos que a exposigco aguda a extrato de pele de conspecmficos promovem respostas comportamentais de fuga, que essa espicie apresenta grande concentragco de cilulas club, as quais devem estar envolvidas nessas respostas e que a exposigco aguda ao estmmulo nco promoveu respostas bioqummicas indicativas de estresse. Considerando que no ambiente natural tais estmmulos devem desaparecer rapidamente dados a diluigco do meio e que respostas rapidas de protegco devem ser desencadeadas frente ` possibilidade de presenga de predador, vias rapidas de suporte a essas respostas, como sistema nervoso simpatico, por exemplo, devem estar envolvidos.

Morfologia, ultraestrutura e morfometria do tegumento da paca (Cuniculus paca Linnaeus, 1766) criada em cativeiro / Morphology, ultrastructure and morphometry of the tegument of paca (Cuniculus paca Linnaeus, 1766) raised in captivity

Considerando-se a falta de informações detalhadas sobre a morfologia da paca, sendo o segundo maior roedor da fauna brasileira, de excelente qualidade de carne e, dada a importância do tegumento comum, inclusive para o bom manejo em cativeiro, e até mesmo estudos como uma opção de animal de experimentação, descreveu-se a morfologia, morfometria e a ultraestrutura da pele de oito pacas (Cuniculus paca) machos e fêmeas, mediante a análise comparativa de segmentos cutâneos das regiões cervical, dorsal e medial do carpo. Observaram-se macroscopicamente as características da pelagem. Parte dos segmentos das regiões cutâneas foi analisada à microscopia de luz e parte, à microscopia eletrônica de varredura. Mensuraram-se as espessuras da derme, epiderme, camada córnea, perfis das fibras de colágeno da derme reticular e a área dos perfis das células das glândulas sebáceas repletas. Analisaram-se os resultados pela estatística descritiva e teste "T" (p<0,001). A coloração da pelagem da paca é castanho avermelhado com cerdas organizadas em grupos. A arquitetura da cútis e os anexos cutâneos se assemelham aos dos mamíferos em geral, embora haja ausência de glândulas sudoríparas. De acordo com a analise morfométrica, pôde-se inferir que a arquitetura da cútis de pacas machos e fêmeas apresenta diferenças quando comparada entre os sexos e também em um mesmo animal, diferenciando-se entre diversas regiões corpóreas.

Considering the lack of detailed information about the morphology of paca, which is the second largest rodent of Brazilian's fauna, with excellent meat quality and, due to the importance of the common integument, we described the morphology, ultrastructure and morphometry of the skin of eight pacas (Cuniculus paca), males and females, through comparative analysis of skin's segments of the cervical, dorsal and medial carpal portions. Macroscopic characteristics of the coat were studied. Part of the segments of cutaneous regions was analyzed by light microscopy, and the other part by scanning electron microscopy. We measured the thickness of dermis, epidermis, stratum corneum, the profiles of the collagen fibers of reticular dermis and the area of filled sebaceous gland cells. The results were analyzed by descriptive statistics and "T" test (p<0.001). The color of the coat is reddish brown with bristles arranged in groups. The architecture of the skin and skin appendages resembles those of mammals in general, although there are no sweat glands. According to the morphometric analysis, this study shows differences of the skin architecture between male and female pacas and also between various body regions in the same animal.

Clareamento da melanina na epiderme do lobo-marinho-sul-americano e sua aplicação na imunohistoquímica enzimática / Bleaching of melanin in the epidermis of south American fur seal and its application on enzyme immunohistochemistry

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.

Recent advances in the molecular pathology of bullous skin disorders

Maintenance of an intact epidermis depends on secure adhesion between adjacent keratinocytes and between basal keratinocytes and underlying epidermal basement membrane. The major adhesion units that achieve this are the hemidesmosomes and desmosomes but when these structures are disrupted, for example by gene mutations or autoantibodies, the resilience of the epidermis is lost and blisters develop. Recently, there have been considerable advances in our understanding of the complex proteins and glycoproteins that contribute to maintaining keratinocyte adhesion via hemidesmosomes and desmosomes, as well as new insight into the molecular pathogenesis of several inherited and autoimmune blistering skin diseases. These new basic scientific data are clinically relevant, helping to improve patient management as well as providing a rationale for developing better and more specific treatments for patients with inherited or acquired blistering skin diseases. This review provides an update on the new information about the molecular pathology of hemidesmosomes and desmosomes that result in bullous skin diseases

Distribution of epidermal melanin pigment among the inhabitants of Karachi

A study was conducted at Department of Anatomy, Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre [JPMC] Karachi, to investigate the distribution of epidermal melanin with respect to age and ethnic groups in Pakistan and intensity of epidermal melanin under ultraviolet radiation among the inhabitants population of Karachi. Epidermal malanin in 5 micro m thick vertical paraffin embedded sections of eighty human skin samples were studied with light microscopy from different age and ethnic groups with schmort technique. The quantity of epidermal melanin diminished as the age advanced. There was no significant difference among different ethnic groups in Pakistan, and the amount of epidermal melanin was significantly higher in exposed than in unexposed parts of body among the population of Karachi. The distribution of epidermal melanin appeared to be inversely proportional to the advancing age, it remained constant among different ethnic groups of Pakistan, but the intensity was significantly higher in exposed than in unexposed parts of body among Karachiites

Ausência de melanócitos na epiderme do gambá (Didelphis azarae) adulto / Absence of melanocytes in the epidermis of the adult opossum (Didelphis azarae)

Estudou-se a presença de melanina na epiderme do gambá (Didelphis azarae). Este pigmento näo foi observado histoquimicamente e o estudo ultra-estrutural confirmou a ausência de melanócitos típicos, com ou sem grânulos de melanina

Sweat glands in man and horse [a light-microscope study]

The sweat glands of horse and man were studied under the same histological conditions by light microscopy. Van Gieson's stain showed two types of secretory cells in both the species. In human sweat glands some cells, which could be resting cells, were seen between secretory and myoepithelial cells. In both species the mode of secretion was eccrine and apocrine in nature