Tejido tiroideo y láser infrarrojo: un estudio morfométrico / Thyroid tissue and infrared laser: a morphometric study

La glándula tiroides posee gran importancia debido a la síntesis y secreción de hormonas, las cuales desempeñan funciones fundamentales para la mantención de la fisiología animal. En este contexto, el objetivo del presente trabajo consistió en determinar parámetros morfométricos de estructuras tiroideas sometidas a estimulaciones con láser infrarrojo (LIR). Para ello, 10 ratas Sprague Dawley de 3 meses de vida y peso aproximado de 200 g, fueron divididas en dos grupos de 5 animales cada uno: grupo control y grupo experimental. Estos últimos recibieron estimulaciones infrarrojas en la tiroides con dosis de 16 J/cm2 durante 15 días seguidos. Una vez sacrificadas las ratas, se extrajeron las glándulas tiroides las que fueron procesadas para microscopía óptica obteniéndose placas histológicas y micrografías con aumentos finales de hasta 1000 X. Se efectuaron estudios morfométricos para determinar en 40 placas, variaciones tisulares generadas por las inducciones infrarrojas, con especial énfasis en la disposición coloidal y dimensiones de folículos y células tiroideas. El análisis de las 40 placas histológicas generados por las inducciones del láser infrarrojo comparados con los controles, reveló que existen marcadas diferencias en todos los componentes del tejido tiroideo analizado, lo cual podría otorgar antecedentes de diferentes funcionalidades en el metabolismo de las glándulas.

The thyroid gland is of great importance because of the synthesis and secretion of hormones which play key roles in the maintenance of animal physiology. In this context, the aim of the present study was to determine morphometric parameters of thyroid structures subjected to infrared laser stimulation (ILS) and for this purpose, 10 Sprague Dawley rats, 3 months of age and weighing approximately 200 grams, were divided into two groups of 5 animals each: the control group and the remaining 5 animals constituting the experimental group received infrared stimulation in the thyroid with doses of 16 J/cm2 for 15 consecutive days. After the rats were sacrificed, the respective thyroids were removed and processed for optical microscopy. Histological plates and micrographs were obtained with final increases of up to 1000 X. Morphometric studies were carried out to determine the tissue variations generated by infrared inductions, with special emphasis on the colloidal arrangement and dimensions of follicles and thyroid cells. Our results revealed that there are marked differences in all the components of the analyzed thyroid tissue which could give antecedents of different functionalities in the metabolism of thyroid glands.

Efecto del láser infrarrojo sobre células tiroideas / Infrared laser effect on thyroid cells

Diez ratas Sprague Dawley de 4 meses de vida y peso aproximado de 250 g fueron divididas en dos grupos de 5 animales cada uno, el grupo A se mantuvo como control y los animales del grupo B recibieron estimulaciones con láser infrarrojo en la tiroides con dosis de 16 J/cm2 durante 15 días consecutivos. Posteriormente las ratas fueron sacrificadas, se extrajeron las respectivas tiroides siendo procesadas para microscopía óptica y se obtuvieron placas histológicas y micrografías de tiroides con aumentos finales de hasta 1000X, las cuales fueron sometidas a estudios morfométricos para determinar en 100 células foliculares: número, áreas y perímetro tanto celular como nuclear, además de disposición coloidal y presencia de vasos sanguíneos. El análisis de los resultados entre las 100 células foliculares pertenecientes a tiroides normal y estimulada revela que existen marcadas diferencias en todos los componentes analizados los que se podría traducir en distintas funcionalidades en el metabolismo de las respectivas glándulas.

Ten 4-month-old Sprague Dawley rats weighing approximately 250 g were divided into two groups of 5 animals each. Group A was the control and the animals in group B received thyroid stimulation with infrared laser in a dose of 16 J/cm2 for 15 consecutive days. Subsequently, rats were euthanized and thyroids were removed and processed for optical microscopy. From both cell types thyroid histological slides and micrographs were obtained with final increases of 400 and 1000X. Morphometric analysis determined the number, areas and cell perimeter as well as colloidal dispersion and presence of blood vessels in 100 follicular cells. Analysis of the results among the 100 follicular cells belonging to normal and stimulated thyroids revealed marked differences in all the analyzed components, which could translate into different functionalities in the metabolism of the respective glands.

Ultrastructure of the thyroid gland in adult West African dwarf goat (Capra hircus) / Ultraestructura de la glándula tiroides en la cabra enana africana occidental (Capra hircus)

The present study examined ultrastructure of the thyroid gland of adult West African Dwarf (WAD) goat in order to further understand the ultrastructural morphology and some of the changes in the components of the thyroid gland in goat with age. Thyroids glands obtained from fifteen adult WAD goats of different ages and sexes slaughtered at the local abattoirs were used in this study. Electron microscopic techniques were used to study the fixed tissue with emphasis on the follicular and parafollicular cells. The results showed that the ultrastructure is generally similar to that of some domestic animals. Follicular cells were cuboidal in young adult goats thyroids but were flattened in older goat thyroids of 5­7 years. These cells remarkably showed highly dilated cisternae of rough endoplasmic reticulum which decreased in frequency the older goats. Microvilli were short and sparse on the follicular cells and the number decreased in the older goats. Different sizes of apical vesicles of varying electron density were encountered that included colloid droplets, secretory vesicles and lysosome-like bodies and the appearance of these vesicles changed with age. Parafollicular cells were encountered in the basal position between follicular cells in all thyroids examined. Numerous dense cytoplasmic granules were observed and they were not apparently different from that described in several mammals.

El presente estudio examinó la ultraestructura de la glándula tiroides en cabra enana de África occidental adulta con el objetivo de tener un mejor conocimiento de la morfología y algunos de los cambios en los componentes de esta glándula en cabras de mayor edad. Se estudiaron glándulas tiroides obtenidas de quince cabras adultas de diferentes edades y sexos, sacrificadas en los mataderos locales. Se utilizaron técnicas de microscopía electrónica para estudiar el tejido con énfasis en las células foliculares y para foliculares. Los resultados mostraron que la ultraestructura generalmente era similar a la de algunos animales domésticos. Las células foliculares en la tiroides de cabras adultas jóvenes eran cúbicas, no obstante en cabras adultas de mayor edad (5 a 7 años) se observaron células aplanadas en las tiroides. Estas células mostraron cisternas de retículo endoplasmático rugoso muy dilatadas que disminuyeron en frecuencia en las cabras de más edad. Las microvellosidades eran cortas y escasas en las células foliculares, y el número disminuyó en las cabras de más edad. Se encontraron diferentes tamaños de vesículas apicales y se observaron gotitas coloidales, vesículas secretoras y organismos similares a los lisosomas; la aparición de estas vesículas fue cambiando en cabras de mayor edad. Se encontraron células parafoliculares en posición basal en todas las células foliculares examinadas. Se observaron numerosos gránulos citoplasmáticos densos sin aparente diferencia de aquellos descritos en otros mamíferos.

Ultrastructural study on thyroid glands of Bufo arenarum larvae kept in potassium perchlorate solution

The ultrastructure of thyroid glands in Bufo arenarum tadpoles was studied with inhibited thyroid function. After hatching, larvae were kept in potassium perchlorate solution, a goitrogenic substance known to prevent absorption of iodine from water or food, resulting in impaired thyroid hormone synthesis. Increased thyroid gland volume and follicular cell height were observed in treated larvae. The changes in size and volume of follicular cells in experimental tadpoles appeared to be mainly a function of the overstimulation of proteinpoietic apparatus. The cell shows a conspicuous development of endoplasmic reticulum and Golgi complex, as well as an increase in number of mitochondria and colloid droplets. These observations in follicular thyroid cells from Bufo arenarum, obtained under such experimental conditions, were interpreted in terms of interruption of negative feedback mechanisms involving the decrease in the thyroxine circulatory level, and therefore the increase in hypothalamo-hypophyseal endocrine secretory stimulation.

Alterations of the rat thyroid gland under experimental conditions

The thiyroid gland of rats, was studied under experimental conditions porvided by administration of several doses of lithium carbonate. It was noted a drug a cumulative effcct on the serum; and the decrease of T3 and T4 hormones in the blood, as well as, the red blood cells, hemoglobin, hematocrit platelets and leukocytes; the diameter of the thy roid follicles, the size of the follicular cells and colloid droplets. On the othcr hand the stroma was invaded by of collagen fibers and blood capillaries.