Sensitization To Calcium Theory Essay

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a) Changes in plasma membrane – *There occurs change in permeability of plasma membrane for the molecules of water and certain other substances like phosphate, potassium, ethylene and glycol etc. *The electrical potential of plasma membrane becomes more positive which gradually becomes more negative.* The change in the potentiality of the membrane is governed by the unequal distribution of chloride ions. b) Ionic changes – There occurs intracellular changes in the concentration of cations particularly in Na+, K+ and Ca++. The changes in concentration of Ca++plays a key role in the metabolic activation of the egg. Certain intracellular changes occur in the concentration…show more content…
However, various theories have been proposed by different embryologists to explain mode of activation of egg. These theories are – 1. Bataillon’s theory – *According to Bataillon (1910) the excretion of substances into the perivitelline space and elevation fertilization membrane activate the egg. *He suggested that the unfertilized egg remains hidden due to accumulation of metabolic products and fertilization causes release of these substances to the exterior. 2. Sensitization to calcium theory – Two theories have been advanced proposed to explain importance of calcium in egg activation. These theories are – “sensitization to calcium” theory of Dlacq, Pasteels and Brachet (1936) and the “Calcium release-protoplasmic clotting” theory of Heilbrunn (1930-1940). *According to these theories – a) In many animal species,isotonic calcium rich solutions act as effective activators. b) The activation of other chemical agents depend upon the presence of calcium ions. c) Depriving the eggs of calcium will sensitize them to subsequent action of calcium

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