AskDefine | Define spermatium

Extensive Definition

The term sperm is derived from the Greek word (σπέρμος) spermos (meaning "seed") and refers to the male reproductive cells. Sperm cells are the smaller gametes involved in fertilization in anisogamy and oogamy. In these types of sexual reproduction, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell. A uniflagellar sperm cell that is motile is also referred to as spermatozoon, whereas a non-motile sperm cell is referred to as spermatium. Sperm cells cannot divide and have a limited life span, but they can fuse with egg cells during fertilization to form a totipotent zygote with the potential to develop into a new organism. Mammalian sperm cells can live for up to 3 days inside the female unless it is exposed to air or is mixed with another liquid.
The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) through meiosis. Sperm cells in algal and many plant gametophytes are produced in male gametangia (antheridia) through mitosis. In flowering plants, sperm nuclei are produced inside pollen.

Motile sperm cells

Motile sperm cells typically move via flagella and require water in order to swim toward the egg for fertilization. The uniflagellated sperm cells (with one flagellum) produced in most animals are referred to as spermatozoa, and are known to vary in size.
Motile sperm are also produced by many protists and the gametophytes of bryophytes, ferns and some gymnosperms such as cycads and ginkgo. The sperm cells are the only flagellated cells in the life cycle of these plants. In many ferns and lycophytes, they are multi-flagellated (carrying more than one flagellum).

Non-motile sperm cells

Non-motile sperm cells called spermatia lack flagella and therefore cannot swim. Spermatia are produced in a spermatangium.
Fungal spermatia (also called pycnidiospores) may be confused with conidia. Conidia are spores that germinate independently of fertilization, whereas spermatia are gametes that are required for fertilization. In some fungi, such as Neurospora crassa, spermatia are identical with microconidia as they can perform both functions of fertilization as well as giving rise to new organisms without fertilization. They move at rapid speeds

Sperm nuclei

In many land plants, including most gymnosperms and all angiosperms, the male gametophytes (pollen grains) are the primary mode of dispersal, for example via wind or insect pollination, eliminating the need for water to bridge the gap between male and female. Each pollen grain contains a spermatogenous (generative) cell. Once the pollen lands on the stigma of a receptive flower, it germinates and starts growing a pollen tube through the carpel. Before the tube reaches the ovule, the nucleus of the generative cell in the pollen grain divides and gives rise to two sperm nuclei which are then discharged through the tube into the ovule for fertilization. More than 50 countries worldwide are importers, including Paraguay, the US, Kenya and Hong Kong.

References

spermatium in Modern Greek (1453-): Σπέρμα
spermatium in Slovak: Spermia
spermatium in Tagalog: Tamod
spermatium in Thai: ตัวอสุจิ
spermatium in Vietnamese: Tinh trùng
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