2. Ultrastructural Development of the Early Rat Otocyst

1977 ◽  
Vol 86 (1_suppl) ◽  
pp. 9-28 ◽  
Author(s):  
William F. Marovitz ◽  
Khalid M. Khan ◽  
Trina Schulte
Keyword(s):  
Stages Of Development ◽  
Surface Ectoderm ◽  
Related Function ◽  
Cellular Death ◽  
Golgi Membranes ◽  
Evolutionary Advantage ◽  
Endolymphatic Duct ◽  
Development And Differentiation ◽  
Luminal Cells

The ultrastructural development and differentiation of cells forming the rat otocyst were studied from the 9th to the 13th postcoital day (PCD). The earliest stage investigated was a simple ovoid structure with a connecting stalk to the surface ectoderm. A process of programmed cellular death involving surface ectoderm, connecting stalk, and lateral otocyst wall rapidly detached the otocyst. The cells forming the otocyst were roughly columnar, the organelles were polarized; mitochondria occurred in greatest number basally and in the supranuclear area; Golgi membranes when present were supranuclear. Luminal cells had many microvilli and cilia of various lengths were detected. The shorter, incompletely formed cilia terminated in small knob-like blebs. With each day the otocysts became more complicated and the endolymphatic duct made its appearance as an evagination of the otocyst. Many more cells were seen to have cilia in various stages of development, and by the 12th PCD possibly each cell of the main otocystic cavity had a kinocilium. Growth of the otocyst due to mitosis occurred to a great extent from a single ventromedial center. Cells in mitosis, although seen at other sites, were in greatest abundance in this area; cellular involution apparently was a related function. Together the process of over-production and programmed cellular involution of supranumerary cells not lost to other causes ( e.g., environmental) may represent an evolutionary advantage.

scholarly journals Characterizing the transcriptional expression and in situ localization of the Dnmt2 gene in Drosophila willistoni

2019 ◽  
Author(s):  
Gilberto Cavalheiro Vieira ◽  
Marícia Fantinel D’Ávila ◽  
Rebeca Zanini ◽  
Pâmela Silva de Oliveira ◽  
Maríndia Deprá ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Biological Function ◽  
Telomeric Region ◽  
Stages Of Development ◽  
Evolutionary Patterns ◽  
Early Stages ◽  
Molecular Features ◽  
Invertebrate Development ◽  
Development And Differentiation

Abstract Background: Organisms that have only the DNA methyltransferase 2 (Dnmt2) to mediate the DNA methylation are called "Dnmt2-only" and they have been investigated in recent surveys. Drosophila is one of the “Dnmt2-only” organisms and is also an ideal model for Dnmt2 research. However, the biological function of the Dnmt2 protein is still uncertain. Some studies have pointed to a putative role during the early stages of invertebrate development. In this work, we present our findings on the Dnmt2 expression in D. willistoni, a neotropical species of large ecological versatility and peculiar molecular features. Results: By RT-PCR and in situ hybridization we demonstrate here the presence of transcripts not only in the early stages of development, but also during the oogenesis. Using qPCR analysis, we verify that Dnmt2 transcription level is higher during early stages of development, though transcription levels are subtly higher in D. willistoni adults than in D. melanogaster levels found in previous studies. We also mapped the Dnmt2 on the IIL chromosome arm (Muller’s B element) of D. willistoni, near at the end of the singular telomeric region. Conclusions: Our findings give insights on the possible biological function of Dnmt2-related processes associated with the development and differentiation of oocytes since germinative tissue formation seems to require a higher expression of Dnmt2. The Dnmt2 localization in the subtelomeric region brings up a series of issues that involve the peculiar characteristics of D. willistoni Dnmt2 enzyme, like evolutionary patterns and the epigenetic phenomena of sex-specific methylation.

scholarly journals Mammary mechanobiology – investigating roles for mechanically activated ion channels in lactation and involution

2020 ◽  
Vol 134 (1) ◽  
pp. jcs248849 ◽  
Author(s):  
Teneale A. Stewart ◽  
Katherine Hughes ◽  
Alexander J. Stevenson ◽  
Natascia Marino ◽  
Adler L. Ju ◽  
...  
Keyword(s):  
Mammary Epithelial Cells ◽  
Functional Expression ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Basal Cells ◽  
Offspring Survival ◽  
Evolutionary Advantage ◽  
Luminal Cells ◽  
And Function ◽  
Mechanical Sensing

ABSTRACTThe ability of a mother to produce a nutritionally complete neonatal food source has provided a powerful evolutionary advantage to mammals. Milk production by mammary epithelial cells is adaptive, its release is exquisitely timed, and its own glandular stagnation with the permanent cessation of suckling triggers the cell death and tissue remodeling that enables female mammals to nurse successive progeny. Chemical and mechanical signals both play a role in this process. However, despite this duality of input, much remains unknown about the nature and function of mechanical forces in this organ. Here, we characterize the force landscape in the functionally mature gland and the capacity of luminal and basal cells to experience and exert force. We explore molecular instruments for force-sensing, in particular channel-mediated mechanotransduction, revealing increased expression of Piezo1 in mammary tissue in lactation and confirming functional expression in luminal cells. We also reveal, however, that lactation and involution proceed normally in mice with luminal-specific Piezo1 deletion. These findings support a multifaceted system of chemical and mechanical sensing in the mammary gland, and a protective redundancy that ensures continued lactational competence and offspring survival.

Linear Arrays of Helical Polyribosomes in Cells Exposed to Antitumor Drug Vincristine Sulfate

1969 ◽  
Vol 27 ◽  
pp. 358-359
Author(s):  
Awtar Krishan
Keyword(s):  
Close Association ◽  
Annulate Lamellae ◽  
Large Array ◽  
Vincristine Sulfate ◽  
Linear Arrays ◽  
Golgi Membranes ◽  
Related Drug ◽  
Drug Leads ◽  
Lethal Doses ◽  
Vinblastine Sulfate

Earle's L-929 fibroblasts treated with mitosis-arresting but sub-lethal doses of vinblastine sulfate (VLB) show hypertrophy of the granular endoplasmic reticulum and annulate lamellae. Exposure of the cells to heavier doses of vincristine sulfate (VCR), a VLB-related drug, leads to the accumulation of large amounts of helical polyribosomes, Golgi membranes and crystals in the cytoplasm. In many of these cells a large number of helical polyribosomes are arranged in prominent linear rows, some of which may be up to 5 micrometers in length. Figure 1 shows a large array of helical polyribosomes near a crystalline mass (CRS) in an Earle's L-929 fibroblast exposed to VCR (5ϒ/ml.) for 3 hours At a higher magnification, as seen in figure 2, the helical polyribosomes are seen arranged in parallel rows. In favorably cut sections, a prominent backbone like "stalk" of finely granular material, measuring approximately 300Å in width is seen in close association with the linear rows of helical polyribosomes.

The ultrastructure of acinar cells in the external orbital gland of young and old male rats

1978 ◽  
Vol 36 (2) ◽  
pp. 276-277
Author(s):  
R. Carriere
Keyword(s):  
Young Adulthood ◽  
Acinar Cells ◽  
Cell Number ◽  
Male Rats ◽  
Polyploid Cell ◽  
Secretory Cells ◽  
Age Changes ◽  
Albino Rat ◽  
Golgi Membranes ◽  
Diploid Cells

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.

Ultrastructural Changes in the Root Meristem Cells of Rubus Chamaemorus L. (Cloudberry)

1975 ◽  
Vol 33 ◽  
pp. 562-563
Author(s):  
Arya K. Bal
Keyword(s):  
Root Meristem ◽  
Uranyl Acetate ◽  
Particulate Material ◽  
Ultrastructural Changes ◽  
Cell Organelles ◽  
Cytoplasmic Matrix ◽  
Golgi Membranes ◽  
Rubus Chamaemorus ◽  
Dense Substance ◽  
Ultrathin Sections

In the course of studies in the root meristem tissue of Rubus chamaemorus L. some important changes in the ultrastructural morphology were observed during the initiation of senescence at the end of the growing season.Root meristems were collected from naturally growing healthy populations of Cloudberry plants, and fixed in Karnovsky's mixture or in 2.5% glutaraldehyde in phosphate buffer. The samples were osmicated, dehydrated following usual methods and embedded in Epon. Ultrathin sections were stained in uranyl acetate and lead citrate.Figure 1 shows part of a dense cell in the meristem. The electron density of these cells is due to large amounts of a particulate material in the cytoplasmic matrix. The smallest particle seen in electron micrographs is about 40 A, although larger aggregates are also found, which remain randomly distributed in association with various cell organelles. Dense substance has been found associated with golgi membranes, proplastids, vacuoles and microtubules (Fig. 2).

Autómatas Celulares Aplicados al Comportamiento de Células de Cáncer Cervicouterino

2019 ◽  
Vol 6 (1) ◽  
pp. 44-49
Author(s):  
Tania Muñoz Jiménez ◽  
Aurora Torres Soto ◽  
María Dolores Torres Soto
Keyword(s):  
Cellular Automaton ◽  
Medical Model ◽  
Research Process ◽  
Simulation Algorithm ◽  
Stages Of Development ◽  
Literary Research ◽  
Migration Dynamics ◽  
Three Stages ◽  
And Migration ◽  
Best Parameters

En este documento se describe el desarrollo e implementación de un modelo para simular computacionalmente la dinámica del crecimiento y migración del cáncer cervicouterino, considerando sus principales características: proliferación, migración y necrosis, así como sus etapas de desarrollo. El modelo se desarrolló mediante un autómata celular con enfoques paralelo y secuencial. El autómata celular se basó en el modelo de Gompertz para simular las etapas de desarrollo de este cáncer, el cual se dividió en tres etapas cada una con diferentes comportamientos durante la simulación. Se realizó un diseño experimental con parámetros de entrada que se seleccionaron a partir de la investigación literaria y su discusión con médicos expertos. Al final del proceso de investigación, se logró obtener un algoritmo computacional de simulación muy bueno comparado con el modelo médico de Gompertz y se encontraron los mejores parámetros para su ejecución mediante un diseño factorial soportado estadísticamente. This paper describes the development and implementation of a model to computationally simulate the growth and migration dynamics of cervical cancer, considering its main characteristics: proliferation, migration and necrosis, as well as its stages of development. The model was developed by means of a cellular automaton with parallel and sequential approaches. The cellular automaton was based on the model of Gompertz to simulate the stages of development of this cancer, which was divided into three stages, each with different behaviors during the simulation. An experimental design was carried out with input parameters that were selected from literary research and its discussion with expert physicians. At the end of the research process, a very good simulation algorithm was obtained compared to the Gompertz medical model and the best parameters for its execution were found by means of a statistically supported factorial design.

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