The Influence of a Gonadotrophin on the Seasonal Changes in the Testis and Deferent Duct of the Chaffinch (Fringilla coelebs)

1949 ◽  
Vol s3-90 (9) ◽  
pp. 1-11
Author(s):  
J. W. SLUITER ◽  
G. J. van OORDT
Keyword(s):  
Interstitial Cells ◽  
Seminiferous Tubules ◽  
Control Bird ◽  
Interstitial Tissue ◽  
Fringilla Coelebs ◽  
Large Numbers ◽  
Different Seasons ◽  
The Difference ◽  
In The Beginning ◽  
Progressive Stage

1. Male chaffinches (Fringilla coelebs) were treated with gestyl, a gonadotrophin prepared from pregnant mare serum, in different seasons; using different techniques their testes and deferent ducts were histologically studied after autopsy on 11 August, 30 November, 28 January, and 5 May. 2. After Champy-fixation and Altmann-staining two types of interstitial cells can be distinguished in the intertubular tissue of sexually active chaffinches: lipoid cells. (= Leydig cells) and secretion cells. 3. Results of gestyl-administration: In summer- and winter-birds (PI. I) whose testes are in the resting stage, the testis-tubule diameter shows a strong enlargement, which is partly due to the plasma of the cells being distinctly inflated; spermatogenesis does not take place. In the intertubular tissue lipoid and secretion cells appear in abnormally large numbers. In 10 days the deferent ducts pass over from the quiescent into the fully-activated stage. In spring-birds (Pl. III), being in the reproductive stage, the administration of gestyl has practically no effect. In this stage the intertubular tissue also contains both lipoid and secretion cells. 4. From the results mentioned under 3, and the fact that in the control bird of 28 January, being in the beginning of the progressive stage (Pl. II), many lipoid cells were found, whereas its deferent ducts were still quiescent, it is concluded that only the secretion cells produce the male sex-hormone. The lipoid cells, which amongst others contain cholesterol, possess only a trophic function. 5. The difference in reaction of the seminiferous tubules of birds to chorionic and hypophyseal gonadotrophins as well as the function of the interstitial cells are discussed. Most opinions on the last-mentioned subject are not sufficiently well founded, as the investigators used routine techniques only for the cytological investigation of the interstitial tissue.

OBSERVATIONS ON CADMIUM DAMAGE AND REPAIR IN RAT TESTES AND THE EFFECTS ON THE PITUITARY GONADOTROPHS

1962 ◽  
Vol 24 (4) ◽  
pp. 453-NP ◽  
Author(s):  
M. ALLANSON ◽  
R. DEANESLY
Keyword(s):  
Subcutaneous Injection ◽  
Cadmium Chloride ◽  
Cytological Study ◽  
Interstitial Cells ◽  
Germinal Epithelium ◽  
Seminiferous Tubules ◽  
Interstitial Tissue ◽  
Long Term Effects ◽  
Single Subcutaneous Injection

SUMMARY Cadmium chloride, in a single subcutaneous injection, can destroy spermatogenic and interstitial cells in the rat testis (Pařízek, 1957) and produce changes in the pituitary. The interstitial tissue is restored by ingrowths from the tunica and full androgen secretion returns before there is any regeneration of germinal epithelium. A cytological study has been made of the peripheral and central pituitary gonadotrophs; the latter revert almost to normal as the interstitial tissue regenerates, whereas the former retain characteristic castration features, unless there is also regeneration of the germinal epithelium. This seems to indicate that in the normal testis there is a hormone contribution from the seminiferous tubules as well as from the interstitial cells. The long-term effects of cadmium on the testis depend on the dose. Early stages of tubule restoration have been studied, but after administration of 0·9 mg., actual proliferation of the germinal epithelium was rarely found—only in four out of twenty rats, 113 or 142 days after injection.

Critical Technical Issues in High Voltage SiC Power Devices

2008 ◽  
Vol 600-603 ◽  
pp. 895-900 ◽  
Author(s):  
Anant K. Agarwal ◽  
Albert A. Burk ◽  
Robert Callanan ◽  
Craig Capell ◽  
Mrinal K. Das ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Carrier Mobility ◽  
Negative Charge ◽  
State Of The Art ◽  
Power Devices ◽  
Power Mosfets ◽  
Large Numbers ◽  
Technical Issues ◽  
The Difference ◽  
Difficult Issue

In this paper, we review the state of the art of SiC switches and the technical issues which remain. Specifically, we will review the progress and remaining challenges associated with SiC power MOSFETs and BJTs. The most difficult issue when fabricating MOSFETs has been an excessive variation in threshold voltage from batch to batch. This difficulty arises due to the fact that the threshold voltage is determined by the difference between two large numbers, namely, a large fixed oxide charge and a large negative charge in the interface traps. There may also be some significant charge captured in the bulk traps in SiC and SiO2. The effect of recombination-induced stacking faults (SFs) on majority carrier mobility has been confirmed with 10 kV Merged PN Schottky (MPS) diodes and MOSFETs. The same SFs have been found to be responsible for degradation of BJTs.

scholarly journals Characteristics of Extratropical Cyclones That Cause Tornadoes in Italy: A Preliminary Study

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 180
Author(s):  
Eigo Tochimoto ◽  
Mario Marcello Miglietta ◽  
Leonardo Bagaglini ◽  
Roberto Ingrosso ◽  
Hiroshi Niino
Keyword(s):  
Environmental Conditions ◽  
Convective Available Potential Energy ◽  
Static Stability ◽  
Extratropical Cyclones ◽  
Cool Season ◽  
Southeastern Us ◽  
Different Seasons ◽  
The Difference ◽  
Upper Level ◽  
Strong Evaporation

Characteristics of extratropical cyclones that cause tornadoes in Italy are investigated. Tornadoes between 2007 and 2016 are analyzed, and statistical analysis of the associated cyclone structures and environments is performed using the JRA-55 reanalysis. Tornadoes are distributed sporadically around the cyclone location within a window of 10° × 10°. The difference in the cyclone tracks partially explains the seasonal variability in the distribution of tornadoes. The highest number of tornadoes occur south of the cyclone centers, mainly in the warm sector, while a few are observed along the cold front. Composite mesoscale parameters are examined to identify the environmental conditions associated with tornadoes in different seasons. Potential instability is favorable to tornado development in autumn. The highest convective available potential energy (CAPE) in this season is associated with relatively high-temperature and humidity at low-levels, mainly due to the strong evaporation over the warm Mediterranean Sea. Upper-level potential vorticity (PV) anomalies and the associated cold air reduce the static stability above the cyclone center, mainly in spring and winter. On average, the values of CAPE are lower than for US tornadoes and comparable with those occurring in Japan, while storm relative helicity (SREH) is comparable with US tornadoes and higher than Japanese tornadoes, indicating that the environmental conditions for Italian tornadoes have peculiar characteristics. Overall, the conditions emerging in this study are close to the high-shear, low-CAPE environments typical of cool-season tornadoes in the Southeastern US.

scholarly journals Large numbers of vertebrates began rapid population decline in the late 19th century

2016 ◽  
Vol 113 (49) ◽  
pp. 14079-14084 ◽  
Author(s):  
Haipeng Li ◽  
Jinggong Xiang-Yu ◽  
Guangyi Dai ◽  
Zhili Gu ◽  
Chen Ming ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Threatened Species ◽  
Driving Forces ◽  
Population Decline ◽  
Cumulative Effect ◽  
Extinction Time ◽  
Time Period ◽  
Large Numbers ◽  
The Difference

Accelerated losses of biodiversity are a hallmark of the current era. Large declines of population size have been widely observed and currently 22,176 species are threatened by extinction. The time at which a threatened species began rapid population decline (RPD) and the rate of RPD provide important clues about the driving forces of population decline and anticipated extinction time. However, these parameters remain unknown for the vast majority of threatened species. Here we analyzed the genetic diversity data of nuclear and mitochondrial loci of 2,764 vertebrate species and found that the mean genetic diversity is lower in threatened species than in related nonthreatened species. Our coalescence-based modeling suggests that in many threatened species the RPD began ∼123 y ago (a 95% confidence interval of 20–260 y). This estimated date coincides with widespread industrialization and a profound change in global living ecosystems over the past two centuries. On average the population size declined by ∼25% every 10 y in a threatened species, and the population size was reduced to ∼5% of its ancestral size. Moreover, the ancestral size of threatened species was, on average, ∼22% smaller than that of nonthreatened species. Because the time period of RPD is short, the cumulative effect of RPD on genetic diversity is still not strong, so that the smaller ancestral size of threatened species may be the major cause of their reduced genetic diversity; RPD explains 24.1–37.5% of the difference in genetic diversity between threatened and nonthreatened species.

scholarly journals Characterization of affine ruled surfaces

1997 ◽  
Vol 39 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Włodzimierz Jelonek
Keyword(s):  
Shape Operator ◽  
Ruled Surfaces ◽  
Affine Sphere ◽  
Affine Surface ◽  
Codazzi Tensor ◽  
Difference Tensor ◽  
The Difference ◽  
In The Beginning ◽  
Affine Metric

The aim of this paper is to give certain conditions characterizing ruled affine surfaces in terms of the Blaschke structure (∇, h, S) induced on a surface (M, f) in ℝ3. The investigation of affine ruled surfaces was started by W. Blaschke in the beginning of our century (see [1]). The description of affine ruled surfaces can be also found in the book [11], [3] and [7]. Ruled extremal surfaces are described in [9]. We show in the present paper that a shape operator S is a Codazzi tensor with respect to the Levi-Civita connection ∇ of affine metric h if and only if (M, f) is an affine sphere or a ruled surface. Affine surfaces with ∇S = 0 are described in [2] (see also [4]). We also show that a surface which is not an affine sphere is ruled iff im(S - HI) =ker(S - HI) and ket(S - HI) ⊂ ker dH. Finally we prove that an affine surface with indefinite affine metric is a ruled affine sphere if and only if the difference tensor K is a Codazzi tensor with respect to ∇.

scholarly journals Dysplastic Development of Seminiferous Tubules and Interstitial Tissue in Rat Hypogonadic (hgn/hgn) Testes1

2004 ◽  
Vol 71 (1) ◽  
pp. 104-116 ◽  
Author(s):  
Hiroetsu Suzuki ◽  
Mio Yagi ◽  
Kenichi Saito ◽  
Katsushi Suzuki
Keyword(s):  
Seminiferous Tubules ◽  
Interstitial Tissue

CHOLESTEROL ESTER HYDROLYSIS BY HOMOGENATES OF WHOLE TESTIS, SEMINIFEROUS TUBULES AND INTERSTITIAL CELLS OF MATURE RATS

1977 ◽  
Vol 75 (2) ◽  
pp. 235-243 ◽  
Author(s):  
J. P. RENSTON ◽  
T. J. IHRIG ◽  
R. H. RENSTON ◽  
B. GONDOS ◽  
R. J. MORIN
Keyword(s):  
Cholesterol Ester ◽  
Incubation Temperature ◽  
Hydrolytic Activity ◽  
Interstitial Cells ◽  
Seminiferous Tubules ◽  
Cholesterol Ester Hydrolase ◽  
Ester Hydrolase ◽  
Optimum Ph ◽  
Hormone Biosynthesis ◽  
Hydrolysis Of

The characteristics and localization of a cholesterol ester hydrolase enzyme in homogenates of whole testis and in isolated seminiferous tubules and interstitial cells of mature rats have been investigated. Hydrolysis of cholesteryl [1-14C]oleate occurred at an optimum pH of 7·0 was linearly related to time up to 5–6 h of incubation and increased linearly up to 0·25 mg protein/incubation. Hydrolytic activity was inhibited by increasing the incubation temperature from 29 to 41 °C and by sonication. Cholesterol ester hydrolase activity/mg protein was three times greater in homogenates of seminiferous tubules than in interstitial cells. Cholesterol ester hydrolase may function to provide precursors for use in seminiferous tubular steroid hormone biosynthesis or germ cell maturation.

scholarly journals Overexpression of the Matrix Metalloproteinase Matrilysin Results in Premature Mammary Gland Differentiation and Male Infertility

1998 ◽  
Vol 9 (2) ◽  
pp. 421-435 ◽  
Author(s):  
Laura A. Rudolph-Owen ◽  
Paul Cannon ◽  
Lynn M. Matrisian
Keyword(s):  
Matrix Metalloproteinase ◽  
Transgenic Animals ◽  
Reproductive Organs ◽  
Mammary Development ◽  
Seminiferous Tubules ◽  
Interstitial Tissue ◽  
Wild Type ◽  
The Matrix

To examine the role of matrilysin (MAT), an epithelial cell-specific matrix metalloproteinase, in the normal development and function of reproductive tissues, we generated transgenic animals that overexpress MAT in several reproductive organs. Three distinct forms of human MAT (wild-type, active, and inactive) were placed under the control of the murine mammary tumor virus promoter/enhancer. Although wild-type, active, and inactive forms of the human MAT protein could be produced in an in vitro culture system, mutations of the MAT cDNA significantly decreased the efficiency with which the MAT protein was produced in vivo. Therefore, animals carrying the wild-type MAT transgene that expressed high levels of human MAT in vivo were further examined. Mammary glands from female transgenic animals were morphologically normal throughout mammary development, but displayed an increased ability to produce β-casein protein in virgin animals. In addition, beginning at approximately 8 mo of age, the testes of male transgenic animals became disorganized with apparent disintegration of interstitial tissue that normally surrounds the seminiferous tubules. The disruption of testis morphology was concurrent with the onset of infertility. These results suggest that overexpression of the matrix-degrading enzyme MAT alters the integrity of the extracellular matrix and thereby induces cellular differentiation and cellular destruction in a tissue-specific manner.

scholarly journals Microscopic Features of Gonadally Inactive Testis of Khaki Campbell Duck (Anas platyrhynchos domesticus) in Bangladesh

2021 ◽  
Vol 9 (1) ◽  
pp. 146-149
Author(s):  
Papia Khatun ◽  
Ziaul Haque ◽  
Shonkor Kumar Das
Keyword(s):  
Leydig Cells ◽  
Anas Platyrhynchos ◽  
Relative Increase ◽  
Seminiferous Tubules ◽  
Interstitial Tissue ◽  
Tissue Samples ◽  
Microscopic Features ◽  
One Year ◽  
Khaki Campbell Ducks ◽  
First Time

The microscopic features of the testis were studied in gonadally inactive Khaki Campbell duck (Anas platyrhynchos domesticus) in Bangladesh. The study was conducted in the Department of Anatomy & Histology, Bangladesh Agricultural University, Mymensingh. Five adult healthy birds of one-year-old were used for this study. The testes were collected immediately after ethical killing of the birds for histological observations. The collected tissue samples were then processed and stained with Hematoxylene & Eosin (H & E) stain for histological observations. The seminiferous tubules showed considerable involution with cessation of spermatogenesis. The basal lamina of the seminiferous tubules was irregular in outline and was invaginated into the germinal epithelium in the form of finger-like plicae or folds. Most of the lumen of the seminiferous tubules was empty and all generation of germ cells were not present in most of the seminifeous tubules. The interstitium showed a relative increase in volume and interstitial tissue consisted of loose connective tissue, interstitial cells (Leydig cells), few connective cells and blood vessels. This study first time described the microscopic features of testis of Khaki Campbell ducks in Bangladesh during inactive phases of the reproductive cycle.

The Preservation of Chesapeake Bay Watercraft

1977 ◽  
Author(s):  
William A. Baker
Keyword(s):  
United States ◽  
Chesapeake Bay ◽  
The United States ◽  
Naval Architecture ◽  
The Past ◽  
Large Numbers ◽  
Sailing Yacht ◽  
The Difference ◽  
Naval Service ◽  
Maritime Heritage

The logo for this Third Chesapeake Sailing Yacht Symposium, the profile of a rakish sailing log canoe superimposed on that of a modern racing sloop, vividly illustrates the difference between the past and the present. Some might say good riddance to the past but there are many good reasons for trying to preserve something of our maritime heritage, not only the larger vessels such as the whaler Charles w. Morgan and the U. S. Corvette Constellation, but the smaller working watercraft as well. Although the Constellation was built in the Bay region, she was designed as a normal ocean-going ship for naval service; she has none of the unique features of Bay naval architecture hence is outside of the scope of this paper. In the days of our grandfathers the Chesapeake Bay region was the home of a multitude of watercraft employed for a wide variety of pursuits from general freighting to crabbing. There were rams, pungies, schooners, sloops, bugeyes, brogans, canoes, bateaux, skiffs, and scows. Of the skiffs alone, it is said that fourteen different designs were recognized on the Bay. While large numbers of these working boats and vessels have disappeared, it is only on Chesapeake Bay, of all the waters of the United States, that a fair variety of local watercraft can be found. Here there is still a chance of preserving for posterity more than isolated examples.

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