Spermatozoa in the Demanian Organ of Female Adoncholaimus Fuscus (Bastian, 1865) (Nematoda)

Calcoen, J.; Dekegel, D.

doi:10.1163/002829679x00151

Cited by 4 publications

(2 citation statements)

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“…In many cases, the Demanian system contains clusters of spermatozoa and functionally may be considered as the overcomplicated spermatheca of enigmatic evolutionary origin. This was confirmed by TEM in the brief communication of Calcoen & Dekegel (1979) who detected spermatozoa in the main duct of Adoncholaimus fuscus, which has Demanian system nearly identical to that of Admirandus multicavus. Our TEM observations of A. multicavus confirmed association of spermatozoa with Demanian system.…”

Section: Discussionsupporting

confidence: 52%

“…However numerous observations of the whole mount specimens (Rachor, 1969) strongly suggest that but one of its functions is a sperm storage analogous to spermatheca or seminal receptacle. Presence of spermatozoa in the Demanian system has been demonstrated unequivocally only once by electron microscopy in the oncholaimid Adoncholaimus fuscus (Calcoen, Dekegel, 1979). However, that study contained little information on spermatozoan ultrastructure in this species.…”

Section: Introductionmentioning

confidence: 98%

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Spermatozoa in the Demanian system of free-living marine nematode Admirandus multicavus (Enoplida: Oncholaimidae)

Yushin

Gliznutsa

2021

Invertzool

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The process of insemination and fertilization in the nematode family Oncholaimidae is of interest because females of many species have extremely unusual sperm storage organ called "Demanian system". The mature spermatozoa from the main duct of the Demanian system of the free-living marine nematode Admirandus multicavus (Enoplida: Oncholaimidae) were studied by the transmission electron microscopy. The main duct is an epithelial tube with thick basal lamina. The dilated part of the duct is occupied by cluster of densely packed spermatozoa 7-8 µm in size, while the narrow part contains occasional strongly elongated sperm cells. The centre of spermatozoa is occupied by a nucleus with poorly condensed chromatin surrounded by a distinct nuclear envelope, the presence of which confirms isolation of enoplids from all other clades of nematodes. The prevalent components of sperm cytoplasm are 'membranous organelles' (MO) which resemble strongly elongated thread-like osmiophilic cisternae densely packed into bundles. Small numerous mitochondria are interspersed between bundles of MOs. Spermatozoa form pseudopods that reflect putative amoeboid cell motility. Amorphous nucleus, threadlike MOs, and numerous minute mitochondria are likely to represent preadaptation to squeezing through the narrow tubular communications of the Demanian system. Present observations of A. multicavus support basic characters of the oncholaimid sperm pattern previously described in another oncholaimid species Pontonema vulgare.

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Section: Discussionsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 98%

Spermatozoa in the Demanian system of free-living marine nematode Admirandus multicavus (Enoplida: Oncholaimidae)

Yushin

Gliznutsa

2021

Invertzool

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The demanian system, traumatic insemination and reproductive strategy in Oncholaimus oxyuris Ditlevsen (Nematoda, Oncholaimina)

Coomans¹,

Verschuren²,

Vanderhaeghen³

1988

Zoologica Scripta

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insemination and reproductive strategy in Oncholaimus oxyuris Ditlevsen (Nematoda, Oncholaimina).-Zool. Scr. 17: 15-23.Observations on living specimens confirm the hypothesis formulated by Chabaud ei al. about traumatic insemination in Oncholairnus oxyuris. A detailed description is given of the copulation, the formation of copulation pores, interstitial channels and the injection of glandular material and sperm. The terminal structures of the demanian system of 0. oxyuris are not pre-existing structures, but are built by the combined action of males, ejaculatory and female substances. The injected sperm is temporarily stored around the uvette in the main duct; from there they reach the uterus through the ductus uterinus. With each copulation, a new copulation pore and interstitial channel are formed. After withdrawal of the spicules a 'wound plug' seals the pore. When copulations follow at short intervals, sperm of the previous insemination are evacuated to the intestine through the osmosium. The hypothesis is formulated that subsequent copulations result in the fertilization of subsequent egg masses by different males.

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Ultrastructure of spermatogenesis in the free-living marine nematodePontonema vulgare(Enoplida, Oncholaimidae)

Yushin¹,

Coomans²,

Малахов³

2002

Can. J. Zool.

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Spermatogenesis in testes of the free-living marine nematode Pontonema vulgare was studied with electron microscopy. The nucleus of spermatocytes has a large nucleolus; the cytoplasm is filled with numerous ribosomes, mitochondria, cisternae of the rough endoplasmic reticulum (RER), Golgi bodies, and flattened osmiophilic cisternae, which are interpreted as the modified membranous organelles (MO) of the spermatozoa of other nematodes studied. After completion of the second meiotic telophase, the nucleus is surrounded by a newly formed nuclear envelope. Further nucleus transformation includes condensation of the chromatin and shrinkage of the nuclear envelope. The deep infoldings of the nuclear envelope give a starlike shape to the nuclei. The cytoplasm of the early spermatids contains the same organelles as in the late spermatocytes, including MO. Many of the latter assume a cuplike or pocketlike shape. During spermatogenesis the peripheral cytoplasm containing the ribosomes, RER, Golgi bodies, and transparent vesicles moves to one pole of the cell forming the residual body. The main cell body of the late spermatid includes the nucleus, mitochondria, and MO embedded in a dense filamentous matrix. The fibrous bodies (FB) of a paracrystalline structure occur in spermatids throughout their developmental transformations. The central part of the spermatozoa contains a starlike nucleus with a nuclear envelope. The filamentous cytoplasm of the spermatozoa includes mitochondria and MO. The spermatozoa extracted from the testes form numerous long filopodia. The dense filamentous cytoplasm of the spermatozoa is continuous with the content of the filipodia. The reconstitution of the nuclear envelope and separate development of MO and FB described in P. vulgare spermatogenesis are the special characters of enoplid nematodes. The reduced character of FB development and simplified structure of MO differentiate P. vulgare from other nematodes studied.

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Spermatozoa in the Demanian Organ of Female Adoncholaimus Fuscus (Bastian, 1865) (Nematoda)

Cited by 4 publications

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Spermatozoa in the Demanian system of free-living marine nematode Admirandus multicavus (Enoplida: Oncholaimidae)

Spermatozoa in the Demanian system of free-living marine nematode Admirandus multicavus (Enoplida: Oncholaimidae)

The demanian system, traumatic insemination and reproductive strategy in Oncholaimus oxyuris Ditlevsen (Nematoda, Oncholaimina)

Ultrastructure of spermatogenesis in the free-living marine nematodePontonema vulgare(Enoplida, Oncholaimidae)

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