Turkish Journal of Fisheries and Aquatic Sciences
2009, Vol 9, Num, 2 (Pages: 215-221)
Atresia and Apoptosis in Preovulatory Follicles in the Ovary of Danio rerio (Zebrafish)
Sema İşisağ Üçüncü 1 ,Özlem Çakıcı 1
1 Ege University, Science Faculty, Biology Department, Zoology Section, 35100 Bornova-Izmir, Turkey
DOI :
10.4194/trjfas.2009.0214
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Although apoptosis, the programmed cell death, is the main mechanism in follicular atresia and especially
postovulatory regression in mammals, its role in fish ovary is still controversial. In order to discuss the possible functions of
atresia as a context of apoptosis, the preovulatory follicles of the freshwater teleost, Danio rerio (zebrafish) were investigated
by light microscopy. The main characteristics of atresia of vitellogenic oocytes of zebrafish were determined as a significant
hypertrophy and hyperplasia of the granulosa cells. The theca cells also became slightly hyperplasic while the zona radiata
was degenerated and the basal membrane located between granulosa and theca was also disintegrated. The aggregation of
compacted chromatin in a crescent pattern, and cell fragmentation that indicates to formation of apoptotic bodies were
evaluated as the morphological evidences for apoptosis in granulosa cells of the oocytes of zebrafish. Towards the end of
atresia, the vitellus is fully degenerated and absorbed, some apoptotic bodies were also observed between the translucent
clusters of theca cells. Apoptotic process was still continued when an atrium had been formed.
Keywords :
Atretic follicle, teleost, Danio rerio, apoptosis