کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2204054 | 1100548 | 2008 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Egg envelope synthesis and chorion modification after oviposition in the dragonfly Libellula depressa (Odonata, Libellulidae)
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم کشاورزی و بیولوژیک (عمومی)
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Libellula depressa (Odonata, Libellulidae) is an exophytic dragonfly ovidepositing eggs in clutches on the surface of floating plants and algae. The present work investigates, at ultrastructural level, the gradual differentiation of the egg envelopes and the chorionic changes after egg deposition in water. The ovary of the mature female of L. depressa is composed of numerous strings of panoistic ovarioles, where the eggshell formation takes place gradually throughout the activity of the follicle cells. The present data show that the egg envelopes are constituted of a very thick electrondense vitelline envelope, a thin endochorion and an extremely thick exochorion composed of a fibrillar matrix resting on a thin electrondense layer. After deposition in water, L. depressa eggs, initially white and almost transparent, gradually become brown spots in a semitransparent jelly coat, rich of incorporated debris. The jelly coat enveloping the eggs of L. depressa derives exclusively from the exochorion, constituted of a fibrillar matrix, which swell at contact with water. The jelly-like coat performs an adhesive function and presumably a protective role during egg segmentation and ensuing larval hatching.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tissue and Cell - Volume 40, Issue 5, October 2008, Pages 317-324
Journal: Tissue and Cell - Volume 40, Issue 5, October 2008, Pages 317-324
نویسندگان
E. Gaino, S. Piersanti, M. Rebora,