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hen she conceived him, and she retired with him to a place far-off.
(مشیّت خدا تحقّق یافت و مریم) بدو باردار شد و با جنین (خود عیسی) در مکان دوردستی گوشه گرفت. [[«بِهِ»: حرف (ب) برای ملابسه و مصاحبه است، یعنی متلبّسه بِهِ (نگا: مؤمنون / 20). «قَصِیّاً»: دور افتاده. بعید.]]
one of the most important requirements for normal development of the embryo is the adequate supply with nutrients from maternal sources. in mammals, the placenta provides the active maternal-fetal interface mediating nutrient transfer between the maternal and embryonic circulation. however, before placental circulation is established, the mammalian visceral yolk sac provides nutrition to the developing embryo during neural tube closure (reviewed in ref. 1). in egg-laying (oviparous) species, such as the chicken (gallus gallus), the functionally equivalent interface is provided by the yolk sac (ys)3 enclosing the yolk. the yolk, deposited into oocytes via receptor-mediated endocytosis of precursor macromolecules synthesized by the liver of the hen (2), is the almost exclusive source of nutrients for the developing embryo, because it contains macromolecular complexes comprising lipids, proteins, vitamins, minerals, and other essential micronutrients. the formation of the mammalian as well as the chicken ys, which when completed are composed of cells derived from all three germ layers, is initiated at the onset of gastrulation (3, 4). progression of avian ys formation is a highly coordinated sequence of events, in which rapidly dividing ectodermal cells start to spread from the embryo to ultimately fully cover the yolk compartment (5). closely behind the migrating front of the ectodermal layer and between the yolk surface and the ectoderm, the proliferating endodermal epithelial cells (eecs) of the ys follow the ectodermal cells and form a tight epithelial layer in close contact with the yolk (5, 6). finally, from the so-called splanchnic mesoderm, which is tightly associated with the basal aspect of the eecs, cells migrate into the space between the ectodermal and endodermal layers and form a network of capillaries in tight contact with the other two cell layers (7). thus, the three cell types in concert generate the fully functional ys capable of mediating the targeted transfer of yolk-derived nutrient components to the embryonic circulation.
یکی از مهمترین نیازهای رشد طبیعی جنین ، تأمین کافی مواد مغذی از منابع مادر است. در پستانداران ، جفت رابط مادر جنین فعال مادر را با واسطه انتقال مواد مغذی بین گردش خون مادر و جنین فراهم می کند. با این حال ، قبل از ایجاد گردش جفت ، کیسه زرده احشایی پستانداران تغذیه جنین در حال رشد را هنگام بسته شدن لوله عصبی فراهم می کند (بررسی شده در شماره 1). در گونه های تخمگذاری (تخمگذاری) ، مک کنید
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