question: How do males generate sperm?
comment: Yes, just like how your bone marrow makes blood cells. Some parts of the body perform their function by making new cells.
passages: Section::::Sperm cells within a male.
   Male
  
  A male (♂) organism is the physiological sex that produces sperm. Each spermatozoon can fuse with a larger female gamete, or ovum, in the process of fertilization. A male cannot reproduce sexually without access to at least one ovum from a female, but some organisms can reproduce both sexually and asexually. Most male mammals, including male humans, have a Y chromosome, which codes for the production of larger amounts of testosterone to develop male reproductive organs. 
   Section::::Vertebrates.
  
  Some vertebrates also reproduce via spermatophores. Males of most salamander and newt species create spermatophores, which the females may choose to take up or not, depending on the success of the male's mating display.
  
  Section::::Descendant.
  
  Spermatophores are believed to be descendants from aquatic creatures(males) that have released sperm into the water. Once the sperm is unearthed, the female spermatophore begins a complex process of unearthing the male deposits where reproduction occurs.
   Male pregnancy
  
  Male pregnancy is the incubation of one or more embryos or fetuses by male members of some species. Most species that reproduce by sexual reproduction are heterogamous—females producing larger gametes (ova) and males producing smaller gametes (sperm). In nearly all animal species, offspring are carried by the female until birth, but in fish of the Syngnathidae family (pipefish, seahorses and the leafy seadragon), males perform this function.
   The first significant development occurred in 1991, in a patent application filed by U.Penn. scientists to fix male sperm by extracting some sperm, correcting a genetic defect in vitro, and injecting the sperm back into the male's testicles. While the vast majority of the patent application dealt with male sperm, one line suggested that the procedure would work with XX cells, i.e., cells from an adult woman to make female sperm.
   Section::::Physiology.
  
  Section::::Physiology.:Fertilization.
  
  Depending on the species, spermatozoa can fertilize ova externally or internally. In external fertilization, the spermatozoa fertilize the ova directly, outside of the female's sexual organs. Female fish, for example, spawn ova into their aquatic environment, where they are fertilized by the semen of the male fish.
   Section::::Male pregnancy.
  
  The male fishes of seahorses, pipefishes, weedy and leafy sea dragons (Syngnathidae) are unusual as the male, rather than the female, incubates the eggs before releasing live fry into the surrounding water. To achieve this, male seahorses protect eggs in a specialized brood pouch, male sea dragons attach their eggs to their legs, and male pipefish may do either.
   Section::::Development.:Puberty.
  
  During puberty increased gonadotropin secretion stimulates a rise in sex steroids creation from the testes. The increased secretion of testosterone from the testes during puberty causes the male secondary sexual characteristics to be manifested.
  
  the manifestation of secondary sexual characteristics include the growth of:
  
  BULLET::::- testes
  
  BULLET::::- pubic hair
  
  BULLET::::- the whole body
  
  BULLET::::- penis
  
  BULLET::::- larynx
  
  BULLET::::- facial and axillary hair
  
  Secondary development includes the increased activity of the eccrine sweat glands and sebaceous glands along with the darkening of the skin in the scrotal region.
  
  Section::::Clinical significance.
  
  Section::::Clinical significance.:Chromosomal abnormalities.
   Sperm is the male reproductive cell. In the types of sexual reproduction known as anisogamy and its subtype oogamy, 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 referred to as a spermatozoon, whereas a non-motile sperm cell is referred to as a spermatium. Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a new organism begins developing, starting as a totipotent zygote. 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. In mammals, sperm develops in the testicles, is stored in the epididymis, and released from the penis.
   The word "sperm" is derived from the Greek word (σπέρμα) "sperma" (meaning "seed"). 
  
  Section::::Sperm in animals.
  
  Section::::Sperm in animals.:Function.
  
  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.
  
  Section::::Sperm in animals.:Anatomy.
  
  The mammalian sperm cell can be divided in 2 parts:
   Animals, including mammals, produce gametes (sperm and egg) through meiosis in gonads (testicles in males and ovaries in females). Sperm are produced by the process of spermatogenesis and eggs are produced by oogenesis. These processes are outlined in the article gametogenesis. During gametogenesis in mammals many genes encoding proteins that take part in DNA repair mechanisms show enhanced or specialized expression These mechanisms include meiotic homologous recombinational repair and mismatch repair.
  
  Section::::Outline of reproduction by species.
  
  BULLET::::- Carnivora#Reproductive system
  
  BULLET::::- Fossa (animal)#Breeding
  
  BULLET::::- Reproductive behavior of canids
  
  BULLET::::- Reproductive behavior of dogs
  
  BULLET::::- Reproductive behavior of wolves
   The major reproductive organs of the male can be grouped into three categories. The first category is sperm production and storage. Production takes place in the testes which are housed in the temperature regulating scrotum, immature sperm then travel to the epididymis for development and storage. The second category are the ejaculatory fluid producing glands which include the seminal vesicles, prostate, and the vas deferens. The final category are those used for copulation, and deposition of the spermatozoa (sperm) within the male, these include the penis, urethra, vas deferens, and Cowper's gland.
   At the time of puberty, androgen levels increase dramatically in males, and androgens mediate the development of masculine secondary sexual characteristics as well as the activation of spermatogenesis and fertility and masculine behavioral changes such as gynephilia and increased sex drive. Masculine secondary sexual characteristics include androgenic hair, voice deepening, emergence of the Adam's apple, broadening of the shoulders, increased muscle mass, and penile growth.
  
  Section::::Biological function.:Spermatogenesis.
   At birth, the development of the prepubertal male reproductive system is completed. During the second trimester of pregnancy, testosterone secretion in the male declines so that at birth the testes are inactive. Gonadotropin secretion is low until the beginning of puberty.
  
  Section::::Development.:Summary.
   Section::::Animals.:Fish.
  
  The vast majority of fish species lay eggs that are then fertilized by the male, some species lay their eggs on a substrate like a rock or on plants, while others scatter their eggs and the eggs are fertilized as they drift or sink in the water column.
   Section::::Biological and physiological aspects.:Physical anatomy and reproduction.:Male anatomy and reproductive system.
  
  Males also have both internal and external genitalia that are responsible for procreation and sexual intercourse. Production of spermatozoa (sperm) is also cyclic, but unlike the female ovulation cycle, the sperm production cycle is constantly producing millions of sperm daily.
  
  Section::::Biological and physiological aspects.:Physical anatomy and reproduction.:Male anatomy and reproductive system.:External male anatomy.
   Human fertilization
  
  Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development. Scientists discovered the dynamics of human fertilization in the nineteenth century.
   In Antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode called by him as epigenetic.
  
  In 1784, Spallanzani established the need of interaction between the female's ovum and male's sperm to form a zygote in frogs. In 1827, von Baer observed a therian mammalian egg for the first time. Oscar Hertwig (1876), in Germany, described the fusion of nuclei of spermatozoa and of ova from sea urchin.
  
  Section::::Evolution.
   The male reproductive system includes testes, rete testis, efferent ductules, epididymis, sex accessory glands, sex accessory ducts and external genitalia.
  
  Testosterone, an androgen, although present in both males and females, is relatively more abundant in males. Testosterone serves as one of the major sexual reproductive hormones in the male reproductive system However, the enzyme aromatase is present in testes and capable of synthesizing estrogens from androgens. Estrogens are present in high concentrations in luminal fluids of the male reproductive tract. Androgen and estrogen receptors are abundant in epithelial cells of the male reproductive tract.
  
  Section::::Animal Reproductive Biology.
   Section::::Purpose.
  
  Spermatogenesis produces mature male gametes, commonly called "sperm" but more specifically known as "spermatozoa", which are able to fertilize the counterpart female gamete, the oocyte, during conception to produce a single-celled individual known as a zygote. This is the cornerstone of sexual reproduction and involves the two gametes both contributing half the normal set of chromosomes (haploid) to result in a chromosomally normal (diploid) zygote.
   The formation of primary spermatocytes (a process known as spermatocytogenesis) begins in humans when a male is sexually matured at puberty, around the age of 10 through 14. Formation is initiated upon the pulsated surges of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which leads to the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) produced by the anterior pituitary gland (Figure 4). The release of FSH into the testes will enhance spermatogenesis and lead to the development of sertoli cells, which act as nursing cells where spermatids will go to mature after Meiosis II. LH promotes leydig cell secretion of testosterone into the testes and blood, which induce spermatogenesis and aid the formation of secondary sex characteristics. From this point on, the secretion of FSH and LH (inducing production of testosterone) will stimulate spermatogenesis until the male dies. Increasing the hormones FSH and LH in males will not increase the rate of spermatogenesis. However, with age, the rate of production will decrease, even when the amount of hormone that is secreted is constant; this is due to higher rates of degeneration of germ cells during meiotic prophase.
   Section::::Fertilisation in animals.
  
  The mechanics behind fertilisation has been studied extensively in sea urchins and mice. This research addresses the question of how the sperm and the appropriate egg find each other and the question of how only one sperm gets into the egg and delivers its contents. There are three steps to fertilisation that ensure species-specificity:
  
  BULLET::::1. Chemotaxis
  
  BULLET::::2. Sperm activation/acrosomal reaction
  
  BULLET::::3. Sperm/egg adhesion
  
  Section::::Fertilisation in animals.:Internal vs. external.
   In some protists, fertilization also involves sperm nuclei, rather than cells, migrating toward the egg cell through a fertilization tube. Oomycetes form sperm nuclei in a syncytical antheridium surrounding the egg cells. The sperm nuclei reach the eggs through fertilization tubes, similar to the pollen tube mechanism in plants.
  
  Section::::Sperm centrioles.
   Human reproduction naturally takes place as internal fertilization by sexual intercourse. During this process, the male inserts his penis, which needs to be erect, into the female's vagina, and then either partner initiates rhythmic pelvic thrusts until the male ejaculates semen, which contains sperm, into the vaginal canal. This process is also known as "coitus", "mating", "having sex", or, euphemistically, "making love". The sperm and the ovum are known as gametes (each containing half the genetic information of the parent, created through meiosis). The sperm (being one of approximately 250 million sperm in a typical male ejaculation) travels through the vagina and cervix into the uterus or Fallopian tubes. Only 1 in 14 million of the ejaculated sperm will reach the Fallopian tube. The egg simultaneously moves through the Fallopian tube away from the ovary. One of the sperm encounters, penetrates and fertilizes the ovum, creating a zygote. Upon fertilization and implantation, gestation of the fetus then occurs within the female's uterus. 
   Section::::Mechanisms.
  
  Section::::Mechanisms.:Female muscular contractions.
  