Digitale Medien
Oxford, UK
:
Blackwell Publishing Ltd
Journal of fish biology
50 (1997), S. 0
ISSN:
1095-8649
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Biologie
Notizen:
The anatomy of the reproductive organs of the gravid female angel sharks Squatina Guggenheim and S. occulta was studied in specimens obtained by bottom trawling off southern Brazil from 1980 to 1992. Gestation of the species is lecithotrophic, lasts 11 months and is synchronized at the population level. The ovulation and onset of gestation occur in summer (January–February) and parturition takes place in spring (November-December). The gestation of Squatina has two phases: uterine gestation during the first 4 months and cloacal gestation during the last 6 months. The transition between these phases occurs in the 5th month (May). During uterine gestation the uteri are turgid, distended longitudinally and transversally, and constricted at both ends. Embryos develop within the closed uteri. During cloacal gestation the dome-shaped uteri are contracted longitudinally and are constricted near the nidamental gland. At the posterior end, they are distended transversally to form a wide opening into the cloaca. The cloaca is distended longitudinally and transversally. The embryos complete their development within the single, heart-shaped, uterine-cloacal chamber, that is open to the exterior through the cloacal Vent.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1095-8649.1997.tb01341.x
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