L. Rebecchi et R. Bertolani, MATURATIVE PATTERN OF OVARY AND TESTIS IN EUTARDIGRADES OF FRESH-WATER AND TERRESTRIAL HABITATS, INVERTEBRATE REPRODUCTION & DEVELOPMENT, 26(2), 1994, pp. 107-117
We studied the life history of tardigrades with a particular focus on
the maturative patterns of the ovary and testis. Specimens collected i
n nature belonging to four species of one freshwater and two semiterre
strial genera of eutardigrades were examined. The females of all exami
ned species are always iteroparous; they have several maturative cycle
s with synchronously developing oocytes. Four maturative stages can be
distinguished in each ovarian cycle, which is clearly correlated with
moulting. In contrast, gametocyte maturation does not seem to be corr
elated with moulting in males and varies markedly in the considered ge
nera. The testes of adult specimens of Macrobiotus always contain both
mature spermatozoa and cells at earlier stages in spermatogenesis (co
ntinuous maturation). The testis of Pseudobiotus megalonyx, the only f
reshwater species examined, shows a gradual increase in spermatozoa th
at in the end completely fill the gonad (progressive maturation, tied
to a semelparous life cycle). The testis in adult males of Amphibolus
is either tilled exclusively with spermatozoa or alternatively with im
mature germinal cells, revealing an iteroparous condition similar to t
hat of the females (cyclical maturation), The different types of gonad
maturation in males seem to be correlated with habitat and the capaci
ty to enter cryptobiosis.