Spermatozoa morphology changes during reproduction and first observation of acrosomal contact in two dioecious species of Macrobiotidae (Tardigrada: Eutardigrada)
Autor: | Kenta Sugiura, Midori Matsumoto |
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Rok vydání: | 2020 |
Předmět: |
Cell Nucleus
Male 0106 biological sciences Reproduction 010607 zoology Tardigrada Zoology Cell Biology Biology Spermatozoa 010603 evolutionary biology 01 natural sciences Human fertilization medicine.anatomical_structure Spermatheca Paramacrobiotus medicine Animals Gamete Female Acrosome Developmental Biology |
Zdroj: | Zygote. 29:42-48 |
ISSN: | 1469-8730 0967-1994 |
DOI: | 10.1017/s0967199420000490 |
Popis: | SummaryMating behaviours for two species of dioecious eutardigrades: a strain of Paramacrobiotus sp. and Macrobiotus shonaicus (Stec et al., 2018) have been recorded previously, and observations have indicated that spermatozoa of both species are first released into the environment, then swim through the cloaca of the females and into the spermatheca. The fusion of gamete nuclei has not yet occurred in a laid egg. Therefore, it has been suggested that fertilization is completed externally as the egg is released into the environment before the nuclei of the gametes fuse. In the present study, the spermatozoa of both Paramacrobiotus sp. and M. shonaicus spermatozoa underwent morphological changes during reproduction. In morphometrical analyses of testicular spermatozoa, the tail, mid-piece, nucleus, and acrosome were significantly longer in Paramacrobiotus sp. compared with M. shonaicus. The nuclei of both the testicular and spermathecal spermatozoa were equally coiled, but the latter had shorter tails in both species. These spermatozoa were present on the surface of the egg chorion after oviposition. The tip of the acrosomes lay buried in the chorion, suggesting that penetration had occurred. We also proposed that the reduced tail is a conserved trait, at least in Macrobiotidae. |
Databáze: | OpenAIRE |
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