Ovarian ultrastructure and vitellogenesis in ten species of shallow-water and bathyal sea cucumbers (Echinodermata: Holothuroidea)

1992 ◽  
Vol 72 (4) ◽  
pp. 759-781 ◽  
Author(s):  
Kevin J. Eckelbarger ◽  
Craig M. Young
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Shallow Water ◽  
Germ Cells ◽  
Deep Sea ◽  
Sea Cucumbers ◽  
Peritoneal Cells ◽  
Ultrastructural Evidence ◽  
Ovarian Structure ◽  
Columnar Cells

Comparative ultrastructural features of the ovary and vitellogenesis have been described for six shallow water and four bathyal species of sea cucumbers representing four major holothuroid orders. Ovarian structure is similar in all ten species except for features of the peritoneal cells of the outer layer and the follicular inner epithelial cells surrounding the developing oocytes. The peritoneal cells vary from monociliated squamous or cuboidal cells to large columnar cells. Ultrastructural evidence suggests that these cells might be capable of incorporating materials from the perivisceral coelom. The follicular inner epithelial cells of two deep-sea species resemble podocytes, a feature previously unre-ported in holothuroid ovaries. It is suggested that these cells function to increase nutrient exchange between the genital haemal sinus and the oocyte during vitellogenesis. In all ten species, the oocytes appear to participate in yolk synthesis through the interaction of the Golgi complex and rough endoplasmic reticulum. The similarity in the ultrastructural features of vitellogenesis suggests that the process of yolk synthesis has been highly conserved in holothuroids. Endocytotic activity was detected in seven of ten species but it is uncertain if this is directly related to vitellogenesis. Cilia and intracellular structures resembling striated ciliary rootlets were observed in the oocytes of four of the ten species studied. The significance of this finding is unclear but could indicate that germ cells have a somatic cell origin.

Memoirs: The Transition of Peritoneal Epithelial Cells into Germ-Cells in Gallus Bankiva

1924 ◽  
Vol s2-68 (269) ◽  
pp. 1-16
Author(s):  
J. BRONTË; GATENBY
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Germ Cells ◽  
Testicular Tissue ◽  
Cytoplasmic Granules ◽  
Peritoneal Cells ◽  
Male Characters

1. In a fowl (Gallus bankiva) which possessed some male characters (comb, wattles, and male pugnacity) the ovary contained an adenoma and was atrophic. 2. Within this effete ovary the peritoneal epithelium had begun to elaborate new testicular tissue. Certain regions outside the gonad contained metamorphosing peritoneal epithelial cells. 3. The transition of avian peritoneal cells into germ-cells takes place in a manner similar to what has already been described in Amphibia (Gatenby). 4. The basophil peritoneal epithelial cell, at first clear, becomes granular. Its nucleus becomes spherical and a pure nucleolus appears: the cytoplasmic granules pass from basophility to osyphility. 5. At this period the cells divide and the oxyphil granules gradually dissolve into a smooth oxyphil ground cytoplasm. The cells, after division, are found to be arranged in columnar manner as spermatic tubules. 6. In each tubule a lumen appears at a later period. 7. Attention has been drawn to the work of Dr. Crew and Miss Fell, who have already described the metamorphosis of peritoneal cells into germ-cells.

Ultrastructural Changes Associated with Alcoholic Hyalin in Hepatocytes and Biliary Epithelial Cells

1971 ◽  
Vol 29 ◽  
pp. 572-573
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Liver Biopsy ◽  
Alcoholic Hepatitis ◽  
Ultrastructural Changes ◽  
Main Mass ◽  
Biliary Epithelial Cells ◽  
Biopsy Specimens ◽  
Alcoholic Hyalin

To learn more of the nature and origin of alcoholic hyalin (AH), 15 liver biopsy specimens from patients with alcoholic hepatitis were studied in detail.AH was found not only in hepatocytes but also in ductular cells (Figs. 1 and 2), although in the latter location only rarely. The bulk of AH consisted of a randomly oriented network of closely packed filaments measuring about 150 Å in width. Bundles of filaments smaller in diameter (40-90 Å) were observed along the periphery of the main mass (Fig. 1), often surrounding it in a rim-like fashion. Fine filaments were also found close to the nucleus in both hepatocytes and biliary epithelial cells, the latter even though characteristic AH was not present (Figs. 3 and 4). Dispersed among the larger filaments were glycogen, RNA particles and profiles of endoplasmic reticulum. Dilated cisternae of endoplasmic reticulum were often conspicuous around the periphery of the AH mass. A limiting membrane was not observed.

Surface Ultrastructure of Human Ectocervix in Certain Pathological Conditions

1985 ◽  
Vol 43 ◽  
pp. 570-571
Author(s):  
S. Mukherjee ◽  
T. Guha ◽  
B. Chakrabarti ◽  
P. Chakrabarti
Keyword(s):  
Epithelial Cells ◽  
Marked Reduction ◽  
Squamous Epithelium ◽  
Malignant Tumour ◽  
Surface Ultrastructure ◽  
Normal Tissues ◽  
Pathological Conditions ◽  
Hexagonal Shape ◽  
Columnar Cells ◽  
Scanning Electron

The cervix is an important organ in reproduction. Its malfunction is frequently a factor for infertility. Ectocervix region does not appear to have received much attention although many studies have been reported on the endocervix. We report here our SEM observations on ectocervix in certain pathological conditions compared to normal ectocervix.Ectocervix specimens from human females with specific pathological disorders were processed for Scanning Electron Microscopy by conventional method and they were examined in a Philips SEM.The normal ectocervix is lined by flat layer of squamous epithelial cells with microridges (Fig. 1). These cells are known to be formed from columnar cells through metaplastic transformation. The cells of carcinoma-bearing ectocervix show a disorganised appearance (Fig. 2). In non-malignant tumour surface some cuboidal and few columnar cells were seen (Fig. 3). A cyst appears like an overgrowth on the surface of the squamous epithelium (Fig. 4). In ulcerated ectocervix a marked reduction of epithelial cells are observed (Fig. 5); the cells are devoid of microridges and, the large polygonal cells, as observed in normal tissues, have somehow acquired comparatively small hexagonal shape

Exosomes: Ultrastructural evidence in epithelial cells of Malpighian tubules

Micron ◽  
2017 ◽  
Vol 100 ◽  
pp. 34-37 ◽  
Author(s):  
Anita Giglio ◽  
Ida Daniela Perrotta ◽  
Pietro Brandmayr
Keyword(s):  
Epithelial Cells ◽  
Malpighian Tubules ◽  
Ultrastructural Evidence

Gametogenesis and the reproductive cycle in the deep-sea anemone Paracalliactis stephensoni (Cnidaria: Actiniaria)

1990 ◽  
Vol 70 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Michel Praet-Van
Keyword(s):  
Organic Matter ◽  
Shallow Water ◽  
Deep Sea ◽  
Phytoplankton Bloom ◽  
Sea Anemone ◽  
Bay Of Biscay ◽  
Sea Anemones ◽  
Spring Phytoplankton Bloom ◽  
Sea Floor ◽  
Ultrastructural Investigation

This ultrastructural investigation of gametogenesis in a deep-sea anemone of the Bay of Biscay trawled around 2000 m depth, contributes to the knowledge of biology and strategy of reproduction of deep-sea benthos.This sea anemone is dioecious. The sperm appears very similar to those of shallow water sea anemones of the genus, Calliactis. The ultrastructural investigation of oogenesis allows the characteristics of the stages of previtellogenesis and vitellogenesis to be defined. The latter begins with a period of lipogenesis correlated with the formation of a trophonema. Mature oocytes measure up to 180 (im in diameter. Study of spermatogenesis and oogenesis reveals that spawning occurs in April/May. In males, the main area of testicular cysts, full of sperm, reaches maximal development from March to May and, in females, the percentage of mature oocytes decreases from 33% in April to 1% in May.Spawning may be induced by the advent in the deep-sea of the products of the spring phytoplankton bloom. This period of spawning, during the increased deposition of organic matter to the deep-sea floor, may be an advantageous strategy for early development of Paracalliactis.

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