Sperm example sentences

The zygote develops into an embryo (with one or two cotyledons) and the PEN develops into endosperm which provides nourishment to the developing embryo.Unlike bryophytes and pteridophytes, in gymnosperms the male and the female gametophytes do not have an independent free-living existence.The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN).Let us also look at classification within angiosperms to understand some of the concerns that influenced the classification systems.In this chapter, we will describe Plantae under Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.This phenomenon of two fusions is called double fertilisation and is unique to angiosperms.The gymnosperms (gymnos : naked, sperma : seeds) are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation.Androgens play a major stimulatory role in the process of spermatogenesis (formation of spermatozoa).The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind.The angiosperms are an exceptionally large group of plants occurring in wide range of habitats.In angiosperms, the male sex organs (stamen) and female sex organs (pistil) are borne in a flower.Unlike the gymnosperms where the ovules are naked, in the angiosperms or flowering plants, the pollen grains and ovules are developed in specialised structures called flowers.The gymnosperms are heterosporous; they produce haploid microspores and megaspores.The testis secretes androgens, which stimulate the development, maturation and functions of the male accessory sex organs, appearance of the male secondary sex characters, spermatogenesis, male sexual behaviour, anabolic pathways and erythropoiesis.In males, FSH and androgens regulate spermatogenesis.