Ultrastructural analysis of the flagellar apparatus in sperm cells ofGinkgo biloba

PROTOPLASMA ◽  
1989 ◽  
Vol 149 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Y. Li ◽  
F. H. Wang ◽  
R. B. Knox
PROTOPLASMA ◽  
1987 ◽  
Vol 139 (1) ◽  
pp. 9-19 ◽  
Author(s):  
C. A. McConchie ◽  
T. Hough ◽  
R. B. Knox

Author(s):  
I. Brent Heath

Detailed ultrastructural analysis of fungal mitotic systems and cytoplasmic microtubules might be expected to contribute to a number of areas of general interest in addition to the direct application to the organisms of study. These areas include possibly fundamental general mechanisms of mitosis; evolution of mitosis; phylogeny of organisms; mechanisms of organelle motility and positioning; characterization of cellular aspects of microtubule properties and polymerization control features. This communication is intended to outline our current research results relating to selected parts of the above questions.Mitosis in the oomycetes Saprolegnia and Thraustotheca has been described previously. These papers described simple kinetochores and showed that the kineto- chores could probably be used as markers for the poorly defined chromosomes. Kineto- chore counts from serially sectioned prophase mitotic nuclei show that kinetochore replication precedes centriole replication to yield a single hemispherical array containing approximately the 4 n number of kinetochore microtubules diverging from the centriole associated "pocket" region of the nuclear envelope (Fig. 1).


Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis

Tilapia, Oreochromis niloticus, is an economically important fish in Saudi Arabia. Elucidation of reproductive biology of this species is necessary for successful breeding program. In this paper we describe fine structure of testicular sperm cells in O, niloticus.Testes from young adult fish were fixed in gluteraldehyde (2%) and osmium tetroxide (1%), both in cacodyl ate buffer. Specimens were processed in the conventional way for electron microscopy and thin sections of tissues (obtained by cutting the blocks with a diamond knife) were stained by ura- nyl acetate and lead citrate. These were examined in a Carl Zeiss electron microscope operated at 40 kV to 60 kV. Sperm cells were obtained from testes by squeezing them in cacodyl ate buffer. They were fixed in gluteraldehyde (2%) in the same buffer, air dried, gold coated and then examined in a Philips scanning electron microscope (SEM) operated at 25kV.The spermatozoon of O. niloticus is consisting of head, midpiece and tail (Fig. 1).


Author(s):  
Gerald Rupp

The marine protozoan Allogromia sp, strain NF Lee extends an elaborate reticulopodial network (RN) which contains an elongate microtubule-(MT)-based cytoskeleton. The MTs are located primarily within cytoplasmic fibrils which are visible by light microscopy (LM) in highly flattened or “two dimensionalized” reticulopodia. It was shown previously that allogromiid RNs withdraw in response to hypertonic Mg2+-seawater. An ultrastructural analysis of this phenomenon indicated that large patches of paracrystalline (PC) material, composed of helical filament aggregates, form concomitant with a decrease in MT number. Similar large patches of PC aggregates are also found in juvenile Allogromia before they extend a RN, which disappear during RN formation. Finally, PC aggregates are occasionally seen near microtubules in normal untreated RNs. Thus there is circumstantial evidence to propose that PC aggregates in Allogromia represent an intermediate form of tubulin; however, more definitive biochemical or immunocytochemical data is not available.


1963 ◽  
Vol 42 (1) ◽  
pp. 97-100
Author(s):  
Mirjam Furuhjelm ◽  
Birgit Johnson ◽  
C.-G. Lagergren

ABSTRACT The pattern of the 17-ketosteroid excretion determined according to Johnsen (1956) in a group of 33 sterile men was compared with that in another group of 14 men with proved fertility, and no difference was found. No correlation between 17-ketosteroid excretion and the concentration of sperm cells or the percentage of abnormal cells could be detected. The results are discussed.


2018 ◽  
Vol 14 (66) ◽  
pp. 120
Author(s):  
R. V. Fafula ◽  
О. K. Оnufrovych ◽  
U. P. Iefremova ◽  
M. Z. Vorobets ◽  
I. A. Nakonechnyi ◽  
...  
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