Related Research Articles
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote.
A boy is a young male human. The term is commonly used for a child or an adolescent. When a male human reaches adulthood, he is usually described as a man.
Preadolescence is a stage of human development following middle childhood and preceding adolescence. It commonly ends with the beginning of puberty. Preadolescence is commonly defined as ages 9–12 ending with the major onset of puberty. It may also be defined as simply the 2-year period before the major onset of puberty. Preadolescence can bring its own challenges and anxieties.
Retrograde ejaculation occurs when semen which would be ejaculated via the urethra is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts before ejaculation, sealing the bladder which besides inhibiting the release of urine also prevents a reflux of seminal fluids into the male bladder during ejaculation. The semen is forced to exit via the urethra, the path of least resistance. When the bladder sphincter does not function properly, retrograde ejaculation may occur. It can also be induced deliberately by a male as a primitive form of male birth control or as part of certain alternative medicine practices. The retrograde-ejaculated semen, which goes into the bladder, is excreted with the next urination.
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells.
In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of children with precocious puberty, the early development is triggered by a disease such as a tumor or injury of the brain. Even when there is no disease, unusually early puberty can have adverse effects on social behavior and psychological development, can reduce adult height potential, and may shift some lifelong health risks. Central precocious puberty can be treated by suppressing the pituitary hormones that induce sex steroid production. The opposite condition is delayed puberty.
Delayed puberty is when a person lacks or has incomplete development of specific sexual characteristics past the usual age of onset of puberty. The person may have no physical or hormonal signs that puberty has begun. In the United States, girls are considered to have delayed puberty if they lack breast development by age 13 or have not started menstruating by age 15. Boys are considered to have delayed puberty if they lack enlargement of the testicles by age 14. Delayed puberty affects about 2% of adolescents.
The Tanner scale is a scale of physical development as children transition into adolescence and then adulthood. The scale defines physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, genitals, testicular volume, and growth of pubic hair. This scale was first quantified in 1969 by James Tanner, a British pediatrician, after a two-decade-long study following the physical changes in girls undergoing puberty.
Adrenarche is an early stage in sexual maturation that happens in some higher primates and in humans, typically peaks at around 20 years of age, and is involved in the development of pubic hair, body odor, skin oiliness, axillary hair, sexual attraction/sexual desire/increased libido and mild acne. During adrenarche the adrenal glands secrete increased levels of weak adrenal androgens, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A4), but without increased cortisol levels. Adrenarche is the result of the development of a new zone of the adrenal cortex, the zona reticularis. Adrenarche is a process related to puberty, but distinct from hypothalamic–pituitary–gonadal axis maturation and function.
Pubarche refers to the first appearance of pubic hair at puberty and also it marks the beginning of puberty. It is one of the physical changes of puberty and can occur independently of complete puberty. The early stage of sexual maturation, also known as adrenarche, is marked by characteristics including the development of pubic hair, axillary hair, adult apocrine body odor, acne, and increased oiliness of hair and skin. The Encyclopedia of Child and Adolescent Health corresponds SMR2 with pubarche, defining it as the development of pubic hair that occurs at a mean age of 11.6 years in females and 12.6 years in males. It further describes that pubarche's physical manifestation is vellus hair over the labia or the base of the penis. See Table 1 for the entirety of the sexual maturity rating description.
Gonadarche refers to the earliest gonadal changes of puberty. In response to pituitary gonadotropins, the ovaries in females and the testes in males begin to grow and increase the production of the sex steroids, especially estradiol and testosterone. The ovary and testis have receptors, follicle cells and leydig cells, respectively, where gonadotropins bind to stimulate the maturation of the gonads and secretion of estrogen and testosterone. Certain disorders can result in changes to timing or nature of these processes.
Thelarche, also known as breast budding, is the onset of secondary breast development, often representing the beginning of pubertal development. It is the stage at which male and female breasts differentiate due to variance in hormone levels; however, some males have a condition in which they develop breasts, termed gynecomastia. Thelarche typically occurs between the ages of 8 and 13 years with significant variation between individuals. However, the initial growth of breast tissue occurs during fetal development.
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
Male infertility refers to a sexually mature male's inability to impregnate a fertile female. In humans it accounts for 40–50% of infertility. It affects approximately 7% of all men. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity. More recently, advance sperm analyses that examine intracellular sperm components are being developed.
Gender dysphoria in children (GD), also known as gender incongruence of childhood, is a formal diagnosis for children who experience significant discontent due to a mismatch between their assigned sex and gender identity. The diagnostic label gender identity disorder in children (GIDC) was used by the Diagnostic and Statistical Manual of Mental Disorders (DSM) until it was renamed gender dysphoria in children in 2013 with the release of the DSM-5. The diagnosis was renamed to remove the stigma associated with the term disorder.
In human anatomy, the penis is an external male intromittent organ that additionally serves as the urinary duct. The main parts are the root (radix); the body (corpus); and the epithelium of the penis including the shaft skin and the foreskin (prepuce) covering the glans penis. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The human male urethra passes through the prostate gland, where it is joined by the ejaculatory duct, and then through the penis. The urethra traverses the corpus spongiosum, and its opening, the meatus, lies on the tip of the glans penis. It is a passage both for urination and ejaculation of semen.
Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Semen is produced and originates from the seminal vesicle, which is located in the pelvis. The process that results in the discharge of semen from the urethral orifice is called ejaculation. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa, and provide a medium through which they can move or "swim". The fluid is adapted to be discharged deep into the vagina, so the spermatozoa can pass into the uterus and form a zygote with an egg.
Ejaculation is the discharge of semen from the male reproductive tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. Ejaculation can occur spontaneously during sleep, and is a normal part of human sexual development. In rare cases, ejaculation occurs because of prostatic disease. Anejaculation is the condition of being unable to ejaculate. Ejaculation is usually very pleasurable for men; dysejaculation is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the condition where semen travels backwards into the bladder rather than out of the urethra.
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testes in a male. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish males and females. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes.
Hypergonadotropic hypogonadism (HH), also known as primary or peripheral/gonadal hypogonadism or primary gonadal failure, is a condition which is characterized by hypogonadism which is due to an impaired response of the gonads to the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and in turn a lack of sex steroid production. As compensation and the lack of negative feedback, gonadotropin levels are elevated. Individuals with HH have an intact and functioning hypothalamus and pituitary glands so they are still able to produce FSH and LH. HH may present as either congenital or acquired, but the majority of cases are of the former nature. HH can be treated with hormone replacement therapy.
References
- ↑ "APA Dictionary of Psychology". dictionary.apa.org. Retrieved 2023-05-02.
- ↑ Adolescence, E. Atwater, Englewood Cliffs, N.J.: Prentice-Hall, 3rd edition, 1992. ISBN 978-0-13-007469-0
- 1 2 Kuhn, Howard E. (1989). "The Onset of Sperm Production in Pubertal Boys". American Journal of Diseases of Children. 143 (2): 190. doi:10.1001/archpedi.1989.02150140080024.
- ↑ Adolescence and Emerging Adulthood: A Cultural Approach, Jeffrey Jensen Arnett, N.J.: Prentice-Hall, 3rd edition, 2006. ISBN 978-0-13-195071-9
- ↑ Nielsen, C. Thøger; Skakkebæk, Niels E.; Richardson, David W.; Darling, Janet A. B.; Hunter, William M.; Jørgensen, Merete; Nielsen, Aage; Ingerslev, Olaf; Keiding, Niels; Müller, Jørn (1986). "Onset of the Release of Spermatozoa (Spermarche) in Boys in Relation to Age, Testicular Growth, Pubic Hair, and Height". The Journal of Clinical Endocrinology & Metabolism. 62 (3): 532–535. doi:10.1210/jcem-62-3-532. PMID 3944237.
- ↑ Eckert-Lind, Camilla; Busch, Alexander S.; Petersen, Jørgen H.; Biro, Frank M.; Butler, Gary; Bräuner, Elvira V.; Juul, Anders (2020-04-06). "Worldwide Secular Trends in Age at Pubertal Onset Assessed by Breast Development Among Girls: A Systematic Review and Meta-analysis". JAMA Pediatrics. 174 (4): e195881. doi:10.1001/jamapediatrics.2019.5881. ISSN 2168-6203. PMC 7042934 .
- ↑ Laron, Zvi (2010). "Age at first ejaculation (spermarche)--the overlooked milestone in male development". Pediatric endocrinology reviews: PER. 7 (3): 256–257. ISSN 1565-4753. PMID 20526238.
- ↑ Song, Y.; Ma, J.; Wang, H.-J.; Wang, Z.; Lau, P. W. C.; Agardh, A. (October 2016). "Age at spermarche: 15-year trend and its association with body mass index in Chinese school-aged boys: Age at spermarche and relation to BMI". Pediatric Obesity. 11 (5): 369–374. doi:10.1111/ijpo.12073.
- 1 2 Adegoke, Alfred A. (April 1993). "The experience of spermarche (the age of onset of sperm emission) among selected adolescent boys in Nigeria". Journal of Youth and Adolescence. 22 (2): 201–209. doi:10.1007/bf01536653. ISSN 0047-2891.
- ↑ Moshang, Thomas (2005). Pediatric Endocrinology: The Requisites in Pediatrics. Mosby. p. 66. ISBN 978-0-323-01825-8. Cites Sun, S. S.; Schubert, C. M.; Chumlea, W. C.; Roche, A. F.; Kulin, H. E.; Lee, P. A.; Himes, J. H.; Ryan, A. S. (1 November 2002). "National Estimates of the Timing of Sexual Maturation and Racial Differences Among US Children". Pediatrics. American Academy of Pediatrics (AAP). 110 (5): 911–919. doi:10.1542/peds.110.5.911. ISSN 0031-4005. PMID 12415029.
- ↑ Stein, James H.; Whisnant Reiser, Lynn (1994). "A study of white middle-class adolescent boys' responses to ?semenarche? (The first ejaculation)". Journal of Youth and Adolescence. 23 (3): 373–384. doi:10.1007/BF01536725. S2CID 143706378.