Physiology of sexual reproduction. I. A histochemical study of the embryo sac development in Zephyranthes rosea and Lagenaria vulgaris.

Using histochemical techniques, changes in the localization of different reserve substances (e.g. pectic compounds, starch, polysaccharides, proteins, nucleic acids, ascorbic acid) and enzymes (Acid phosphatase, alkaline phosphatase, ATP-ase, 5-nucleotidase, esterase, phosphorylase, succinate dehydrogenase, cytochrome oxidase and lipase) have been studied in the young and fertilized ovules of Zephyranthes sp. and Lagenaria sp. etc. Extensive changes in the enzyme activity and reserve substances are demonstrated during megasporogenesis and megagametogenesis and most of the substances exhibited interesting distributional pattern. Similarly, all the enzymes investigated have specific locale of distribution in the tissues which displayed differentiation of embryo sac. The earlier changes observed are in the megaspore which contained many reserve substances (starch; nucleic acids; ascorbic acid; proteins) and enzymes (peroxidase, succinate dehydrogenase, acid phosphatase, alkaline phosphatase and ATP-ase). In the matured embryo sac different cells have differential localization of the substances. Based on histochemical studies, distinct differences are made out between egg and synergids; egg and central cell. In general antipodals have maximum accumulation of physiologically active substances and intense activity of different enzymes. Nucellus cells also stored diverse substances and enzymes especially towards the chalazal end. Pollination stimulated accumulation of several reserve substances and enzymes in the tip of nucellus beak, micropylar zone and these included starch, peroxidase, phosphorylase succinate dehydrogenase, cytochrome oxidase etc.