Head: contains the nucleus with densely coiled chromatin fibers, surrounded anteriorly by a thin, flattened sac called the acrosome, which contains enzymes used for penetrating the female egg.The mammalian sperm cell can be divided in 2 parts: Anatomy Sperm and egg fusing ( fertilisation) Dimensions of the human sperm head measured from a 39 year-old healthy human subject The main sperm function is to reach the ovum and fuse with it to deliver two sub-cellular structures: (i) the male pronucleus that contains the genetic material and (ii) the centrioles that are structures that help organize the microtubule cytoskeleton. Video of human sperm cells under a microscope Evolutionįurther information: Spermatozoon Function The word sperm is derived from the Greek word σπέρμα, sperma, meaning "seed". In mammals, sperm is stored in the epididymis and is released from the penis during ejaculation in a fluid known as semen. The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell with 46 paired chromosomes. Sperm cells cannot divide and have a limited lifespan, but after fusion with egg cells during fertilisation, a new organism begins developing, starting as a totipotent zygote. This whole process occurs constantly and takes around 3 months from start to finish. The spermatids then mature and, in animals, construct a tail, or flagellum, which gives rise to the mature, motile sperm cell. The spermatocytes then undergo meiosis, reducing their chromosome number by half, which produces spermatids. This process involves the production of several successive sperm cell precursors, starting with spermatogonia, which differentiate into spermatocytes. Sperm cells form during the process known as spermatogenesis, which in amniotes ( reptiles and mammals) takes place in the seminiferous tubules of the testes. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm. Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Sperm ( PL: sperm or sperms) is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). For other uses, see Sperm (disambiguation).
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