Spermatozoa in the reproductive system of a hermaphroditic marine tardigrade, Orzeliscus belopus (Tardigrada

Arthrotardigrada)

Atsushi C Suzuki, Reinhardt Møbjerg Kristensen

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Orzeliscus belopus has long been regarded as the only hermaphroditic marine tardigrade, yet there has been no published detailed information on its internal anatomy. Our study elucidates the ultrastructure of the ovotestis and the spermatozoa of Orzeliscus cf. belopus from Bermuda. The ovotestis had no septum to separate male and female germ cells and, while early stages of spermatogenesis were not observed, many spermatozoa were found at the periphery in both anterior and posterior areas of the gonad. The nucleus and the mitochondria of the spermatozoa in the ovotestis extend backward from the centriole region, forming a half-headed arrow-shape with the nucleus on the outer side of the 'arrowhead'. The cross section of a long vesicular body (the paranuclear vesicle) is dumbbell- or horseshoe-shaped and attached to almost the entire length of the nucleus. In the seminal receptacle, we found both a complete spermatozoon and some which started to degrade. There is an indication that sperm is further modified after discharge as within the receptacle duct the sperm is no longer half-headed arrow-shaped but has a straight nucleus. This modification might be correlated with the degeneration of the paranuclear vesicle. Our observations clearly show that O. belopus is a simultaneous hermaphrodite, and suggests that the reproductive mode includes copulation and cross-fertilization.

Original languageEnglish
Pages (from-to)497-511
Number of pages15
JournalZoologischer Anzeiger
Volume253
Issue number6
DOIs
Publication statusPublished - 2014

Fingerprint

Tardigrada
reproductive system
spermatozoa
centrioles
Bermuda
fertilization (reproduction)
spermatogenesis
copulation
gonads
germ cells
ultrastructure
mitochondria

Keywords

  • Bermuda
  • Hermaphrodites
  • Ovotestis
  • Sperm
  • Tardigrada
  • Ultrastructure

ASJC Scopus subject areas

  • Animal Science and Zoology

Cite this

Spermatozoa in the reproductive system of a hermaphroditic marine tardigrade, Orzeliscus belopus (Tardigrada : Arthrotardigrada). / Suzuki, Atsushi C; Kristensen, Reinhardt Møbjerg.

In: Zoologischer Anzeiger, Vol. 253, No. 6, 2014, p. 497-511.

Research output: Contribution to journalArticle

@article{7582f8c2b8534d2493f72501510bee91,
title = "Spermatozoa in the reproductive system of a hermaphroditic marine tardigrade, Orzeliscus belopus (Tardigrada: Arthrotardigrada)",
abstract = "Orzeliscus belopus has long been regarded as the only hermaphroditic marine tardigrade, yet there has been no published detailed information on its internal anatomy. Our study elucidates the ultrastructure of the ovotestis and the spermatozoa of Orzeliscus cf. belopus from Bermuda. The ovotestis had no septum to separate male and female germ cells and, while early stages of spermatogenesis were not observed, many spermatozoa were found at the periphery in both anterior and posterior areas of the gonad. The nucleus and the mitochondria of the spermatozoa in the ovotestis extend backward from the centriole region, forming a half-headed arrow-shape with the nucleus on the outer side of the 'arrowhead'. The cross section of a long vesicular body (the paranuclear vesicle) is dumbbell- or horseshoe-shaped and attached to almost the entire length of the nucleus. In the seminal receptacle, we found both a complete spermatozoon and some which started to degrade. There is an indication that sperm is further modified after discharge as within the receptacle duct the sperm is no longer half-headed arrow-shaped but has a straight nucleus. This modification might be correlated with the degeneration of the paranuclear vesicle. Our observations clearly show that O. belopus is a simultaneous hermaphrodite, and suggests that the reproductive mode includes copulation and cross-fertilization.",
keywords = "Bermuda, Hermaphrodites, Ovotestis, Sperm, Tardigrada, Ultrastructure",
author = "Suzuki, {Atsushi C} and Kristensen, {Reinhardt M{\o}bjerg}",
year = "2014",
doi = "10.1016/j.jcz.2014.07.003",
language = "English",
volume = "253",
pages = "497--511",
journal = "Zoologischer Anzeiger",
issn = "0044-5231",
publisher = "Urban und Fischer Verlag Jena",
number = "6",

}

TY - JOUR

T1 - Spermatozoa in the reproductive system of a hermaphroditic marine tardigrade, Orzeliscus belopus (Tardigrada

T2 - Arthrotardigrada)

AU - Suzuki, Atsushi C

AU - Kristensen, Reinhardt Møbjerg

PY - 2014

Y1 - 2014

N2 - Orzeliscus belopus has long been regarded as the only hermaphroditic marine tardigrade, yet there has been no published detailed information on its internal anatomy. Our study elucidates the ultrastructure of the ovotestis and the spermatozoa of Orzeliscus cf. belopus from Bermuda. The ovotestis had no septum to separate male and female germ cells and, while early stages of spermatogenesis were not observed, many spermatozoa were found at the periphery in both anterior and posterior areas of the gonad. The nucleus and the mitochondria of the spermatozoa in the ovotestis extend backward from the centriole region, forming a half-headed arrow-shape with the nucleus on the outer side of the 'arrowhead'. The cross section of a long vesicular body (the paranuclear vesicle) is dumbbell- or horseshoe-shaped and attached to almost the entire length of the nucleus. In the seminal receptacle, we found both a complete spermatozoon and some which started to degrade. There is an indication that sperm is further modified after discharge as within the receptacle duct the sperm is no longer half-headed arrow-shaped but has a straight nucleus. This modification might be correlated with the degeneration of the paranuclear vesicle. Our observations clearly show that O. belopus is a simultaneous hermaphrodite, and suggests that the reproductive mode includes copulation and cross-fertilization.

AB - Orzeliscus belopus has long been regarded as the only hermaphroditic marine tardigrade, yet there has been no published detailed information on its internal anatomy. Our study elucidates the ultrastructure of the ovotestis and the spermatozoa of Orzeliscus cf. belopus from Bermuda. The ovotestis had no septum to separate male and female germ cells and, while early stages of spermatogenesis were not observed, many spermatozoa were found at the periphery in both anterior and posterior areas of the gonad. The nucleus and the mitochondria of the spermatozoa in the ovotestis extend backward from the centriole region, forming a half-headed arrow-shape with the nucleus on the outer side of the 'arrowhead'. The cross section of a long vesicular body (the paranuclear vesicle) is dumbbell- or horseshoe-shaped and attached to almost the entire length of the nucleus. In the seminal receptacle, we found both a complete spermatozoon and some which started to degrade. There is an indication that sperm is further modified after discharge as within the receptacle duct the sperm is no longer half-headed arrow-shaped but has a straight nucleus. This modification might be correlated with the degeneration of the paranuclear vesicle. Our observations clearly show that O. belopus is a simultaneous hermaphrodite, and suggests that the reproductive mode includes copulation and cross-fertilization.

KW - Bermuda

KW - Hermaphrodites

KW - Ovotestis

KW - Sperm

KW - Tardigrada

KW - Ultrastructure

UR - http://www.scopus.com/inward/record.url?scp=84930043456&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84930043456&partnerID=8YFLogxK

U2 - 10.1016/j.jcz.2014.07.003

DO - 10.1016/j.jcz.2014.07.003

M3 - Article

VL - 253

SP - 497

EP - 511

JO - Zoologischer Anzeiger

JF - Zoologischer Anzeiger

SN - 0044-5231

IS - 6

ER -