失眠症
发表于 2025-3-27 00:30:08
Lecture 6,ion of which single cells are capable and the great extent to which an organism can establish separate functional structures without dividing itself into cells. The course of development in an individual cell and in a sequence of cell generations can be laid out in a strict sequence and thus lead di
Favorable
发表于 2025-3-27 01:14:44
Lecture 7,larity; but in nature there are also go od-sized organisms which are not organized into cells, but in which a variety of “ organs” and reproductive events occur in a single individual. Most often this increase in size is connected with the presence of many nuclei in an undivided cytoplasmic mass; wh
Defiance
发表于 2025-3-27 07:52:10
Lecture 8,lant Protista. In many cases, it is a matter of definition as to whether one calls something a colony of single-celled individuals or a single multicellular organism. The bases of such a decision may include the ability of isolated cells to survive, the degree of organization into tissues, and the d
Ornament
发表于 2025-3-27 12:19:35
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Offbeat
发表于 2025-3-27 15:22:38
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Irrepressible
发表于 2025-3-27 21:30:27
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飞行员
发表于 2025-3-28 01:53:54
Lecture 12,m. We call such a layer of morphologically still undifferentiated cells a blastema (F. E. .). It is characteristic for many phyla that, in the development of the germ layers and organs, such cell layers, rather than individual cells, play the main role. From the primitive blastema of the blastoderm,
Malleable
发表于 2025-3-28 02:13:15
Lecture 13,alization either of materials or of metabolic processes. For the experimental approach to this problem the discovery has been of great importance that early development of echinoids can be shifted in a vegetal or in an animal direction by exposure to certain chemical substances.
intolerance
发表于 2025-3-28 08:34:58
Lecture 14,d to reproduce at will. The embryos are quite accessible in all developmental stages. Thanks to the yolk supply which every cell contains, embryonic parts are nutritionally independent until the differentiation of the larval organs is completed, in contrast to fish and reptile embryos, which draw th
不能和解
发表于 2025-3-28 13:20:16
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