Effects of ovariectomy on the secretory apparatus in the right atrial cardiomyocytes of middle-aged mice

OBJECTIVE : The aim of the present study was to evaluate the effects of ovariectomy on the secretory apparatus of natriuretic peptides in right atrial cardiomyocytes. METHODS: Nine-month-old mice underwent bilateral ovariectomy or sham surgery. The blood exam of the ovariectomized mice showed results consistent with castrated females. Systolic blood pressure was measured after ovariectomy (9 mo of age) and at the moment of sacrifice (12 mo of age). Fragments of the right atrium were collected and prepared for electron microscopy examination. The following variables were quantified: the quantitative density and area of the natriuretic peptide granules, the relative volume of euchromatin in the nucleus, the number of pores per 10 μm of the nuclear membrane and the relative volumes of the mitochondria and Golgi complex. RESULTS: The cardiomyocytes obtained from ovariectomized mice indicated that the quantitative density and the area of secretory granules of natriuretic peptides were significantly lower compared with the sham-operated mice. Furthermore, there was a decrease in the relative volume of euchromatin, a lower density of nuclear pores, and lower relative volumes of the mitochondria and Golgi complex in the ovariectomized mice compared with the sham-operated mice. These findings suggest a pool with a low turnover rate, i.e., low synthesis and elimination of natriuretic peptides. CONCLUSION: A lack of estrogen caused hypotrophy of the secretory apparatus in right atrial cardiomyocytes that could explain the weak synthesis of natriuretic peptides in mice. Furthermore, one of the mechanisms of blood pressure control was lost, which may explain, in part, the elevated blood pressure in ovariectomized mice. .

Ultrastructural changes of the olfactory bulb in manganese-treated mice

The effect of manganese toxicity on the ultrastructure of the olfactory bulb was evaluated. Male albino mice were injected intraperitoneally with MnCl2 (5 mg/Kg/day) five days per week during nine weeks. The control group received NaCl (0.9%). The olfactory bulbs of five mice from each group were processed for transmission electron microscopy after 2, 4, 6 and 9 weeks of manganese treatment. On week 2, some disorganization of the myelin sheaths was observed. After 4 weeks, degenerated neurons with dilated cisternae of rough endoplasmic reticulum and swollen mitochondria appeared. A certain degree of gliosis with a predominance of astrocytes with swollen mitochondria, disorganization of the endomembrane system, dilation of the perinuclear cisternae and irregularly shaped nuclei with abnormal chromatin distribution were observed after 6 weeks. Some glial cells showed disorganization of the Golgi apparatus. On week 9, an increase in the number of astrocytes, whose mitochondrial cristae were partially or totally erased, and a dilation of the rough endoplasmic reticulum were found. Neurons appear degenerated, with swollen mitochondria and a vacuolated, electron dense cytoplasm. These changes seem to indicate that the olfactory bulb is sensitive to the toxic effects of manganese.

Ultrastructural Aspects of Spermatids in Isogenic Black Mouse C57BL6J / Aspectos Ultraestructurales de las Espermátidas en el Ratón Negro Isogénico C57BL6

The objective of this study was to describe some changes in spermatids differentiating events during spermiogenesis, leading to spermatozoa final formation. The animals were sacrificed with ethylic acid inhalation and, then, testis fragments were collected, fixed in Karnovsky and post-fixed in osmium tetroxide. After dehydration, the sections were stained with uranyl acetate 2%. It was observed in early spermatids at Golgi phase, formation of acrosomal granule contained in the acrosomal vesicle, spheroidal nucleus with rugous reticulum around it, and Golgi apparatus made up of lamellae and vesicular structures. At cephalic hood phase, the granule suffers flattening and the marginal fossa is formed. In both phases, it was possible to observe the presence of multivesicular body. At acrosomal phase, the acrosomal system is set up, and several enzymes of endoplasmatic reticulum as well chromatoid body are observed in the cytoplasm. At the last phase, that is, maturation, the nucleus becomes more elongated, the endoplasmatic reticulum regresses, the Golgi apparatus approaches to the flagellum and mitochondrias align next to it.

El objetivo del estudio, fue describir algunas alteraciones producidas en la espermiogénesis, en los eventos que diferencian a las espermátidas y que llevan a la formación final de los espermatozoides. Los ratones fueron sacrificados con inhalación de éter etílico y, enseguida, se recolectaron fragmentos de testículos, los que fueron fijados en Karnovsky y tetróxido de osmio. Después de la deshidratación, los cortes fueron teñidos con acetato de uranilo al 2 %. En espermátidas jóvenes en la fase de Golgi se observan: formación del gránulo acrosómico contenido en la vesícula acrosómica, núcleo esferoidal con retículo rugoso a su alrededor, y aparato de Golgi formado por lamelas y estructuras vesiculares. En la fase de capuz cefálico, el gránulo sufre achatamiento y se forma la fosa marginal. En estas dos fases fue posible observar la presencia del cuerpo multivesicular. En la fase acrosómica se establece el sistema acrosómico, distingiéndose en el citoplasma muchas vesículas de retículo endoplasmático y cuerpo cromatoide. En la última fase, la de maduración, el núcleo se torna más alargado, el retículo endoplasmático retrae, el aparato de Golgi se aproxima al flagelo y las mitocondrias se alinean a lo largo de él.

Zinc Iodide-Osmium Tetroxide (ZIO) Reactive Golgi Apparatus in the Principal Cells of Dog Epididymal Epithelium / El Tetróxido de Zinc Iodide-Osmio (ZIO) Reactiva el Aparato de Golgi en las Células Principales del Epitelio Epididimal del Perro

The cisternae of the Golgi apparatus of dog epididymal principal cells were labeled by the zinc iodide-osmium tetroxide method (ZIO). These cisternae were observed in the supranuclear region of the cytoplasm of the epididymal principal cells. Abundant endoplasmic reticulum cisternae, multivesicular bodies, mitochondria, lysosomes and vesicular elements of variable size were also found in this region, all associated with the sacks of the well-developed Golgi apparatus. The use of the ZIO method facilitates the observation and identification of the cisternae of the Golgi apparatus, thus permitting a correlation between structure and function in the so-called Golgi area. These ultrastructural characteristics support the secretory role of epididymal principal cells in the dog.

La cisterna del aparato de Golgi de las células principales del epidídimo del perro, fueron tratados con el método de tetróxido de zinc iodide-osmium (ZIO). Estas cisternas fueron observadas en la región supranuclear del citoplasma de las células principales del epidídimo. Abundante cisternas del retículo endoplasmático, cuerpos multivesiculares, mitocondrias, lisosomas y elementos vesiculares de tamaño variable, fueron encontrados en esta región, todos asociados con los sacos del aparato de Golgi maduro. El uso del método de ZIO facilita la observación e identificación del aparato de Golgi, permitiendo efectuar una correlación entre estructura y función en el área de Golgi. Estas características estructurales suponen el rol secretorio de las células epididimarias principales en el perro.

Tissue alterations in the Guinea pig lateral prostate following antiandrogen flutamide therapy

The flutamide antiandrogenic effects on the Guinea pig male prostate morphology in puberal, post-puberal and adult ages were evaluated in the present study. Daily-treated group animals received flutamide subcutaneous injection at a dose of 10 mg/Kg body weight for 10 days. The control group animals received a pharmacological vehicle under the same conditions. The lateral prostate was removed, fixed and processed for light and transmission electron microscopy. The results revealed an increase of the acinus diameter in the treated puberal animals and straitness in the stromal compartment around the acini. The epithelial cells exhibited cubic phenotype. In the post-puberal and adult animals, a decrease of the acinus diameter was observed, as well as an increase of the smooth muscle layer and presence of the folds at epithelium. The ultrastructural evaluation of the secretory cells in the treated group demonstrated endomembrane enlargement, mainly in the rough endoplasmic reticulum and Golgi apparatus. In addition, a decrease of the microvilli and alterations in the distribution patterns and density of the stromal fibrillar components were observed. In conclusion, the flutamide treatment exerts tissue effects on the lateral prostate, promoting stroma/epithelium alterations.

A unique mechanism of nuclear division in Giardia lamblia involves components of the ventral disk and the nuclear envelope

The fine structure of the binucleate, parasitic protist Giardia lamblia during interphase and divisional stages was studied by serial thin sectioning and three-dimensional reconstructions. The earlier sign of nuclear division is the development of a few peripheral areas of densely packed chromatin directly attached to the inner nuclear envelope. An intracytoplasmic sheet of ventral disk components grows from the cell periphery towards one of the nuclei, apparently constricting this nucleus, which becomes located at a ventral bulge. After the basal bodies become duplicated, a full nuclear division occurs in trophozoites, giving two pairs of parent-daughter nuclei. This full division occurs in a dorsal-ventral direction, with the resulting nuclear pairs located at the sides of the two sets of basal bodies. A new ventral disk is formed from the disk-derived sheets in the cell harboring the four nuclei. Cytokinesis is polymorphic, but at early stages is dorsal-to-dorsal. Encysting trophozoites show the development of Golgi cisternae stacks and dense, specific secretory granules. 3-D reconstructions show that cysts contain a single pair of incompletely strangled nuclei. The dividing Giardia lacks a typical, microtubular spindle either inside or outside the nuclei. The nuclear envelope seems to be the only structure involved in the final division of the parent-daughter nuclei.

Fine structural study of the red seaweed Gymnogongrus torulosus (Phyllophoraceae, Rhodophyta)

The present study analyzed several characters of the red seaweed Gymnogongrus torulosus, such as cellular structure of the thallus, cuticle, pit plug and cell wall ultrastructure, and morphology of some organelles like plastids, Golgi bodies and mitochondria. Also, anomalous chloroplasts with thylakoid disorganization were found in medullary cells. The significance of this thylakoid disposition is still unclear. This is one of the first studies focused on the fine structure of a red alga recorded in Argentina.

Scanning electron microscopy of acinar cells of rat submandibular salivary glands

1. The submandibular salivary gland of rats was observed by high-resolution scanning electron microscopy employing the aldehyde-osmium-DMSO-osmium method. 2. The intracellular membranous components and sponge-like structures of basement membrane containing the fine collagen fibrils of acinar cells were clearly identified in three dimensional images. The granular endoplasmic reticulum and Golgi apparatus showed the luminal surface. The mitochondria were small, ranging in diameter from 0.3 to 0.5 µm, and revealed their cristae. The secretory granules ranged in diameter from 0.3 to 1.4 µm. ribosome granules were attached to the surfaces of cisterns, and measured 20 to 25 nm in diameter. 3. The contact areas between the acinar cells revealed numerous cytoplasmic protrusions. In the striated duct cells, the mitochondria were arranged vertically and surrounded by nasal infoldings of the plasma membranes. At high magnification, the mitochondrial cristae were visualized in their three-dimensional characteristics

Detection of cholesterol by digitonin in coated membranes of the Golgi complex in the guinea pig spermatid

En la face de maduración o condensación del complejo de Golgi de la espermátide de cobayo, se presentan las membranas de las cisternas densas y de las vesículas de condensación con características especiales que las diferencian del resto de las membranas del Golgi. Las membranas de la fase de condensación son más gruesas, están en su mayor parte cubiertas por una trama poligonal del tipo característico de la clathrina y tratadas con la técnica de la digitonina forman los típicos rulos y agujas del complejo digitonina-colesterol. Esta observación revela que ambos componentes - clathrina y colesterol - pueden coincidir en la misma membrana, se concentran en la cara interna del Golgi y por fusión de membranas se transfieren a la membrana externa del acrosoma

Electron Microscopic Observations on the Morphological Changes of Rat Mesentric Mast Cells Induced by Morphine HCl

The effects of morphine HCI on the rat mesenteric mast cells were studied with the electron microscopy. The materials were prepared for electron microscopy by osmium tetroxide fixation and embedding in Epon. The rat mesenteric mast cells showed no distinct morphological changes due to morphine HCl, but the mast cell granlues were changed in various ways. For instance, they formed dusters, showed granular lysis, and an appearance of electron transparency. Frequently, some granules appeared in the extracellular space and the boundary of the granules was not evident. From the results mentioned above, it was suggested that rat mesenteric mast cell granules were affected by morphine HCl in the shape, the granular matrix, and the granular boundaries.