Germination, barriers

No adverse effects were noted in the testes. The results of this study indicate that lead affected spermatozoa after release from the germinal epithelium which was possibly protected from the effects of lead by the blood-testes barrier (Barratt et al. 1989). 

The cerebral endothelial cells of the blood-brain barrier originate from the middle germinal sheet of the embryo, the mesoderm [17]. Concomitant with migration and proliferation of capillary endothelial cells during formation of the cerebral vascular network occurs the imprinting of the cells. Thereby, induction by the cellular surrounding plays an important role [18-21], The relevance of the cellular environment for the development of the barrier function of cerebral microvessels was first demonstrated by Stewart and Wiley [22], who transplanted embryonic brain tissue of a quail into embryonic gut tissue of chicken and vice versa. The cerebral transplant was vascularized by intestinal vessels, in which properties of the blood-brain barrier had been induced. In transplanted brain vessels, however, no characteristics of a barrier could be demonstrated, due to the lack of a neuronal environment. These results indicated that the cerebral microvessels are of extraneuronal origin, with properties that are induced by the cellular environment. In addition, brain tissue has the capability to induce blood-brain barrier characteristics also in noncerebral vascular tissue [23],... 

HV146 Kanauchi O., T. Iwanaga, K. Mitsu-yama, et al. Butyrate from bacterial fermentation of germinated barley foodstuff preserves intestinal barrier function in experimental colitis in the rat model. J Gastroenterol Hepatol 1999 14(9) 880-888. 

Probably the most commonly referred to compound which accounts for a form of passive resistance of a chemical nature is protocatechuic acid (6.16) which is found in yellow and red skinned onions and prevents the germination of spores of the onion smudge fungus, Colletotrichum circinans. Thus, protocatechuic acid serves as a barrier to infection prior to penetration. Once penetration occurs the compound is ineffective. 

Transporters are critical in the function of capillary endothelium, where they contribute to the blood-brain, blood-germinal epithelium (blood-testis and blood-ovary), and blood-placental barriers. Endothelial cells in each of these tissues express high levels of MDR-1. The existence of a blood-brain barrier is well established and is thought to arise... 

Protection Offered Reports indicate that antitranspirants form a barrier on leaves to prevent disease organisms such as powdery mildew spores from germinating and infecting plants. However, these products are not approved and registered for use as fungicides. 

Seed and fruit coats can act as barriers to the uptake of water and thus prevent or retard germination. They can also affect respiration by limiting the permeability to oxygen. Coat effects on germination and the restriction of gaseous exchange is another topic reserved for the second volume. 

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