Growth embryos

The rate law describing embryo growth can be written as the product of two factors ... 

As the product of two factors which vary oppositely with increasing r, the rate of embryo growth passes through a maximum at some critical (subscript c) dimension. 

Initially, the cytotoxicity against chick embryo fibroblasts of BPA, tyrosine, tyrosine dipeptide, and the dipeptide derivatives used in the synthesis of the polymers shown in Fig. 7 were evaluated in a comparative experiment (43). The surface of standard tissue culture wells was coated with 5 mg of each test substance. Then the adhesion and proliferation of the fibroblasts was followed over a 7-day period. Among all test substances, BPA was clearly the most cytotoxic material. Monomeric tyrosine derivatives containing the ben-zyloxycarbonyl group were also cytotoxic, while tyrosine itself, tyrosine dipeptide, and most of the protected dipeptide derivatives did not noticeably interfere with cell growth and adhesion and were therefore classified on a preliminary basis as possibly "nontoxic."... 

Embryonated hens eggs are still the most convenient hosts for the growth of the vimses that are needed for influenza and yellow fever vaccines. Influenza vimses accumulate in high litre in the allantoic fluid of the eggs and yellow fever vims accumulates in the nervous systems of the embryos. 

EMBRYO GROWTH RATE EQUATIONS FOR VARIOUS CASES... 

To this point, we have examined diffusion growth in terms of nucleatlon and embryo formation. Let us now explore the actual species which diffuse in the lattice. 

Let us now reconsider our nucleation models of 4.4.1., specifically Models B, D and E. These are examples of phase-boundary controlled growth involving random nucleation. We now assume an exponential embryo formation law (see 4.4.7), with isotopic growth of nuclei in three dimensions and k2 as the rate constant. By suitable manipulation of 4.4.6.,... 

Although the above is complicated, it does aptly illustrate the various mechanisms involved when atoms (ions) migrate by diffusion and start to form a new structure by formation of incipient embryos, then nuclei and finally the growth of phase boundaries. 

In Nature, however, we always have a contiiinous distribution of particles. This means that we have all sizes, even those of fractional parentage, i.e.-18.56n, 18.57p, 18.58 p, etc. (supposing that we can measure 0.01 p differences). The reason for this is that the mecheuiisms for particle formation, i.e.- precipitation, embryo and nucleation growth, Ostwald ripening, and sintering, are random processes. Thus, while we may speak of the "statistical variation of diameters", and while we use whole numbers for the particle diameters, the actuality is that the diameters are fractional in nature. Very few particle-size" specialists seem to recognize this fact. Since the processes are random in nature, we can use statistics to describe the... 

Growth at the level of the organism is an increase in cell number, cell mass, extracellular mass, fluid content and other components of the body that result in an increase of body mass. The mammalian body has very different growth phases with different functions. The pre-implantation embryo does not grow, but only divides, fuelled by materials that were deposited in the egg before fertilization. After implantation there is very rapid cell division which is tightly coupled to cell differentiation in the process of gastrulation — the creation of the different lineages... 

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