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)
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم دامی و جانورشناسی
پیش نمایش صفحه اول مقاله

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
Journal: Zoologischer Anzeiger - A Journal of Comparative Zoology - Volume 251, Issue 1, March 2012, Pages 71-82
نویسندگان
Piotr ÅwiÄ
tek, Anna Z. Urbisz, Witold StrużyÅski, Bartosz J. PÅachno, Aleksander Bielecki, StanisÅaw Cios, Erno Salonen, Jerzy Klag,