کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2790711 1154783 2012 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ovary architecture of two branchiobdellid species and Acanthobdella peledina (Annelida, Clitellata)
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک علوم دامی و جانورشناسی
پیش نمایش صفحه اول مقاله
Ovary architecture of two branchiobdellid species and Acanthobdella peledina (Annelida, Clitellata)
چکیده انگلیسی
In all of the species studied, the ovaries are made up of germ-line cysts associated with somatic (follicular) cells. The architecture of a germ-line cyst is exactly the same as in other clitellate annelids that have been studied to date. Each germ cell in a cyst has one stable cytoplasmic bridge connecting it with a central anuclear cytoplasmic mass, a cytophore. The fate of germ cells constituting cysts is diverse. The majority of the cells withdraw from meiosis and become nurse cells; only a few continue meiosis, grow and become oocytes. The meroistic mode of oogenesis is suggested. We suggest also that the formation of germ-line cysts and ovary meroism should be regarded as basal conditions for all Clitellata. The occurrence of ovisacs enveloping the ovaries in A. peledina and Hirudinida is regarded as a synapomorphy of both groups, whereas ovaries found in B. pentodonta and B. parasitica have no ovisacs and resemble ovaries described in Oligochaeta sensu stricto.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Zoologischer Anzeiger - A Journal of Comparative Zoology - Volume 251, Issue 1, March 2012, Pages 71-82
نویسندگان
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