The fine structure of spermatogenesis in Hymenolepis diminuta (Cestoda) with a description of the mature spermatozoon

1977 ◽  
Vol 54 (2) ◽  
pp. 175-187 ◽  
Author(s):  
G. H. Kelsoe ◽  
John E. Ubelaker ◽  
Venita F. Allison
Keyword(s):  
Fine Structure ◽  
Mature Spermatozoon ◽  
Hymenolepis Diminuta

Spermatogenesis and the fine structure of the mature spermatozoon of the liver fluke, Fasciola hepatica (Trematoda: Digenea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 395-407 ◽  
Author(s):  
A. W. Stitt ◽  
I. Fairweather
Keyword(s):  
Fine Structure ◽  
Liver Fluke ◽  
Central Body ◽  
Fasciola Hepatica ◽  
Mature Spermatozoon ◽  
Basal Bodies ◽  
Nuclear Region ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Median Process

SUMMARYSpermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.

The fine structure of the cysticercoid of Hymenolepis diminuta

1975 ◽  
Vol 46 (3) ◽  
pp. 229-239 ◽  
Author(s):  
Nancy B. Cooper ◽  
V. F. Allison ◽  
John E. Ubelaker
Keyword(s):  
Fine Structure ◽  
Hymenolepis Diminuta

Spermatogenesis and the fine structure of the mature spermatozoon in the free proglottis ofTrilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea)

1989 ◽  
Vol 75 (4) ◽  
pp. 287-298 ◽  
Author(s):  
S. Mahendrasingam ◽  
I. Fairweather ◽  
D. W. Halton
Keyword(s):  
Fine Structure ◽  
Mature Spermatozoon

Fine structure of the mature spermatozoon of rhynchocinetes typus, crustacea decapoda

1983 ◽  
Vol 7 (1) ◽  
pp. 1-18 ◽  
Author(s):  
E. Dupré ◽  
C. Barros
Keyword(s):  
Fine Structure ◽  
Mature Spermatozoon

The fine structure of the cysticercoid of Hymenolepis diminuta

1972 ◽  
Vol 39 (2) ◽  
pp. 137-147 ◽  
Author(s):  
Venita F. Allison ◽  
John E. Ubelaker ◽  
Nancy B. Cooper
Keyword(s):  
Fine Structure ◽  
Hymenolepis Diminuta

scholarly journals ELECTRON MICROSCOPE STUDY OF SPERMIOGENESIS IN A FIRE-BRAT INSECT, THERMOBIA DOMESTICA PACK

1964 ◽  
Vol 23 (3) ◽  
pp. 431-446 ◽  
Author(s):  
S. R. Bawa
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Membrane System ◽  
Mature Spermatozoon ◽  
Axial Filament ◽  
Thermobia Domestica ◽  
Complex Membrane ◽  
Coarse Fibers

The fine structure of the mature spermatozoon of the insect Thermobia domestica has been investigated. This flagellate spermatozoon is unique with respect to the relative positions of the centriole, nucleus, mitochondrial nebenkern derivatives, and acrosome along the length of the cell. The acrosome lies at the posterior end of the nucleus. Unlike spermatozoa of most animals, the Thermobia spermatozoon has a nucleus that reveals an unusual lamellar pattern of the material inside of it. This flagellate spermatozoon is also unusual in its tendency to intertwine with other spermatozoa, and during movement the intertwined portion of two (double) spermatozoa is always directed forwards. In the axial filament complex, one of the fibrils of each peripheral double fibril bears a hook-shaped process. An indistinct granular material is seen between the 9 outer coarse fibers. Cytoplasmic tubules, probably corresponding to the "microtubules" of other investigators (67), have been observed around the nucleus, mitochondrial nebenkern derivatives, axial filament complex, and acrosome. A description is given of a complex membrane system which surrounds and separates the main organelles of the cell from each other.

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