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Topic: Secondary sexual characteristics

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In the News (Mon 17 Jun 19)

  Secondary sex characteristic Summary
Secondary sexual characteristics are generally distinguishing of gender in the human male and female.
In males, the outward secondary sexual characteristics include the growth of the larynx and the appearance of the "Adam's apple." Changes in the larynx and elongation of the vocal cords result in a deepening voice associated with males.
Secondary sex characteristics are traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system.
www.bookrags.com /Secondary_sex_characteristic   (885 words)

Secondary sexual characteristics are characteristics that are sex related but are not directly connected with the physiology of reproduction (the sex organs).
The development of secondary sexual characteristics before 8 years of age in girls is uncommon and little is known of its epidemiology.
The mean age of the first appearance of the secondary sexual characteristics was breast 11.84 +/- 0.95 years, pubic hair 13.29 +/- 1.11 years, axillary hair 13.71 +/- 1.21 years; the average age of developmental maturation was breast 13.95 +/- 1.16 years, pubic hair 14.85 +/- 1.29 years, axillary hair 15.14 +/- 1.24 years.
sociologyindex.com /secondary_sexual_characteristics.htm   (950 words)

 Sexual Selection   (Site not responding. Last check: 2007-10-11)
t was Charles Darwin who originally proposed that the so-called secondary sexual characteristics of male animals -- such as the elaborate tails of peacocks, bright plumage or expandable throat sacs in many birds, large racks in mooses, deep voices in men -- evolved because females preferred to mate with individuals that had those features.
In birds, the first form of sexual selection occurs when males compete for territories, as is obvious when those territories are on leks (traditional mating grounds).
That second type of sexual selection, in which one sex chooses among potential mates, appears to be the most common type among birds.
www.stanford.edu /group/stanfordbirds/text/essays/Sexual_Selection.html   (1199 words)

 Sexual Selection
Darwin (1871) developed the notion of sexual selection because he realized that not all of the differences between males and females were due to their specialized roles in sexual reproduction.
Sexual Selection is also noteworthy because it has the potential to become a "runaway" process in which there is no obvious optimum set of characters.
Sexual selection may also play a role in the process of speciation because mate preferences are obvious foundations for premating reproductive isolating mechanisms.
www.towson.edu /~scully/sexual_selection.html   (1581 words)

  Python Sexing and Breeding   (Site not responding. Last check: 2007-10-11)
There are no secondary sexual characteristics that contribute to a major difference in appearance or behavior between the two sexes.
While there are minor secondary sexual characteristics, such as the length of the tail and the size of the ventral spurs, without another snake of both sexes to compare it to this method of sexual determination is unreliable.
Sexual maturity is usually determined by size with age having a small effect on sexual maturity.
www.angelfire.com /al/repticare/page23.html   (1940 words)

 Human Sexuality: Common Definitions
SEXUALITY - the state of having sex - the collective characteristics that mark the differences between the male and the female or the constitution and life of an individual as related to sex; all the dispositions related to intimacy, whether associated with sex organs or not.
Sexual Identity: based on the person’s sexual characteristic, such as external and internal genitalia, hormonal characteristics and secondary sexual characteristics.
Characteristics: Physiologic state in which sexual tension is released and contractions are produces in various organs.
www.sikhwomen.com /Sexuality/Common_Sex_Definitions.htm   (790 words)

  SEX DIFFERENCES IN COGNITION.   (Site not responding. Last check: 2007-10-11)
Females can rank the characteristics of sequentially presented males, for example female three-spined sticklebacks are more likely to show interest in a male if his red colouring is brighter than a previously seen male, and more likely to reject a male if his colouring is duller than one previously seen.
Hamilton and Zuk (1982) proposed that secondary male sexual characteristics (plumage colour, tail feather length, antler size etc) facilitate female appraisal of the males ability to withstand the detrimental effect of parasitism.
This theory is thus a modification of the ‘handicap principle’ as the development and maintenance of secondary sexual characters may be a considerable handicap.
psych.unn.ac.uk /users/nick/EPlec04.htm   (2855 words)

 secondary sexual characteristic
In many cases, they are involved in displays and contests for mates and have evolved by sexual selection.
Their development is stimulated by sex hormones – in humans the change in concentrations of these hormones at puberty results not only in the development of the physical secondary sexual characteristics, but also emotional changes.
In humans the development of secondary sexual characteristics is stimulated at puberty by the hormone oestrogen in women and testosterone in men.
www.tiscali.co.uk /reference/encyclopaedia/hutchinson/m0008107.html   (353 words)

 [No title]
Sexual selection, which implies the possession of considerable perceptive powers and of strong passions, seems to have been more effective with the lamellicorns than with any other family of beetles.
With some species the males are provided with weapons for fighting; some live in pairs and show mutual affection; many have the power of stridulating when excited; many are furnished with the most extraordinary horns, apparently for the sake of ornament; and some, which are diurnal in their habits, are gorgeously coloured.
The belief that the stridulation serves as a sexual call is supported by the fact that death-ticks (Anobium tessellatum) are well known to answer each other's ticking, and, as I have myself observed, a tapping noise artificially made.
www.zoo.uib.no /classics/darwin/descent.chap10.txt   (8490 words)

 eMedicine - Precocious Pseudopuberty : Article by Cydney L Fenton, MD, FAAP
Precocious puberty is typically defined as the appearance of any sign of secondary sexual maturation in boys younger than 9 years, in white girls younger than 7 years, and in African American girls younger than 6 years.
The classic definition of sexual precocity for girls is the onset of secondary sexual characteristics prior to the age of 8 years.
Secondary sexual characteristics are staged using the Tanner growth charts for breasts and pubic hair in girls and pubic hair in boys.
www.emedicine.com /ped/topic1881.htm   (5481 words)

Primary amenorrhea is the absence of menstrual bleeding and secondary sexual characteristics (for example, breast development and pubic hair) in a girl by age 14 years or the absence of menstrual bleeding with normal development of secondary sexual characteristics in a girl by age 16 years.
Secondary amenorrhea is the absence of menstrual bleeding in a woman who had been menstruating but later stops menstruating for 3 or more months in the absence of pregnancy, lactation (the ability to breastfeed), cycle suppression with systemic hormonal contraceptive (birth control) pills, or menopause.
For a woman to have regular menstrual cycles, her hypothalamus, pituitary gland (see Anatomy of the Endocrine System), ovaries, and uterus should all be functioning normally.
www.emedicinehealth.com /amenorrhea/article_em.htm   (229 words)

 Secondary sex characteristic - Wikipedia, the free encyclopedia
Secondary sex characteristics are traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system.
They are opposed to the primary sexual characteristics: the sex organs.
Sexual differentiation begins during gestation, when the gonads form.
en.wikipedia.org /wiki/Secondary_sexual_characteristics   (327 words)

 Gonadotropin-Independent Precocious Puberty - Lucile Packard Children's Hospital
Estrogen is a group of hormones produced by the ovary, placenta, and testes that also stimulate secondary sexual characteristics in males and females.
Sometimes called pseudoprecocious puberty, this form of early puberty is characterized by the development of most secondary sexual characteristics, although the sexual glands remain undeveloped.
Although the sexual glands themselves remain immature, hypersecretion of androgen and estrogen cause the development of most other secondary sexual characteristics.
www.lpch.org /DiseaseHealthInfo/HealthLibrary/diabetes/gipp.html   (434 words)

 [No title]   (Site not responding. Last check: 2007-10-11)
Women have two X chromosomes, ovaries, all of the internal plumbing to transport urine and ova to the outside world, a system to support pregnancy and fetal development, as well as a variety of recognizable secondary sexual characteristics.
A second cause stems from the fact that all humans, no matter what their chromosomal makeup, have the biological capacity to develop either male or female genitalia and secondary sexual characteristics while in the womb.
Developmentally, some babies are born with male or female chromosomal makeup and with both male and female genitalia, or with some of the genitalia of the opposite chromosomal sex.
www.lycos.com /info/intersexual--males.html   (738 words)

 The Secular Trend
The development of secondary sexual characteristics in girls is a significant event, signaling the onset of physiological and psychological changes of profound importance to the individual.
Giddens reported that the onset of secondary sexual characteristics, breast buds and pubic hair, were significantly different among white and African-American girls.
Their median age of sexual maturation are now among one of the earliest medians in the world population studied.
www.mc.maricopa.edu /dept/d46/psy/dev/fall00/Seculartrend/trend.html   (929 words)

 ReCAPP: Journal Summary (September 2002): Secondary Sexual Characteristics and Menses in Young Girls Seen in Office ...
If pediatricians are seeing younger and younger girls with early breast development, pubic hair growth, and menstruation, they need to be prepared to detect and discuss these changes with their patients.
The timing of sexual education in schools may have to be adjusted over time to incorporate these findings.
For each specific characteristic that was measured — breast development, pubic hair growth, and axillary hair growth — African-American girls developed earlier and faster than their White counterparts.
www.etr.org /recapp/research/journal200209girls.htm   (927 words)

 Key Papers - Marcia
This is a cross sectional study reporting several variables related to sexual development from 17 077 young girls presenting in physicians offices in North Carolina.
This is significant in that it presents data from a very large cohort of girls and suggests that there is a sizable subpopulation of girls whose sexual development is accelerated relative to the general population.
Further, the data suggest that the relative size of this accelerated population is greater in fl girls than in white girls.
www.emcom.ca /Key/marcia.shtml   (369 words)

 Secondary Characteristics
The secondary sexual characteristics begin to appear during puberty as a result of hormonal stimulation.
In the male, the first body changes of puberty are the growth of the testicles, the appearance of pubic hair at the base of the penis, and an enlargement of the penis.
During puberty females develop their secondary sexual characteristics of which the breasts are the most obvious.
www2.hu-berlin.de /sexology/ATLAS_EN/html/secondary_characteristics.html   (889 words)

 Zoology 304, Evolution
So-called "primary" sexual characteristics are those sexually dimorphic traits which are directly related to the production of differentiated eggs or sperm.
The ways in which selection acts to shape secondary sexual characteristics is called sexual selection.
The result, as Fisher realized, can be "runaway sexual selection" in which both trait and preference become more and more exaggerated until the process is halted by some counteracting tradeoff (or by extinction).
www.science.siu.edu /zoology/king/304/ch09.htm   (807 words)

Puberty is a transitional stage between childhood and adulthood when secondary sexual changes occur, fertility is achieved and skeletal growth is completed.
Ninety-nine percent of females in the United States will have at least one secondary sexual characteristic by age thirteen and ninety-nine percent of boys will have one characteristic by age fourteen years.
Delayed puberty is defined as no signs of secondary sexual characteristics by age thirteen in girls and fourteen years in boys.
www.mgh.harvard.edu /children/adolescenthealth/articles/aa_puberty.aspx   (1006 words)

 Anthro 212: Sexual Selection   (Site not responding. Last check: 2007-10-11)
In the sex with the lower PI, reproduction is limited by sexual access to the opposite sex.
Female choice leads to sexual dimorphism: if females use certain male characteristics (e.g., brightness and redness of plumage) to assess male quality, then these "attractive" traits will be selected for in males, and become more exaggerated over time.
A fascinating review of male- and female-oriented views of sexual selection and primate behavior is Sarah Blaffer Hrdy's essay: Empathy, polyandry, and the myth of the coy female.
www.rci.rutgers.edu /~palombit/L212-14-SexualSelec.html   (563 words)

 Puberty and adolescence
Puberty refers to the period of sexual maturation.
Puberty is when the child experiences physical, hormonal, and sexual changes and becomes capable of reproduction.
It is associated with rapid growth and the appearance of secondary sexual characteristics.
www.pennhealth.com /ency/article/001950.htm   (1190 words)

 What Is a Chicken? - Incubation and Embryology - University of Illinois Extension
The comb is the red appendage on the top of the head, and the wattles are the two appendages under the chin.
These are secondary sexual characteristics and are more prominent in the male.
A strain is a group or breeding population within a variety or cross that has been bred and developed by a person or organization to possess certain desirable characteristics.
www.urbanext.uiuc.edu /eggs/res08-whatis.html   (1115 words)

 Physiological Psychology: A Neuroscience Approach Chapter 12 -- Chapter Outline   (Site not responding. Last check: 2007-10-11)
—sexual dimorphism in humans is a source of controversy
In mammals, most factors that determine whether sexual behavior will lead to conception is under the control of females.
Sexual dimorphism: dimorphism in genitalia creates dimorphism among motor neurons controlling their muscles.
cwx.prenhall.com /smock/chapter12/custom1/deluxe-content.html   (991 words)

 PROS - Secondary Sexual Characteristics Study
The PROS Secondary Sexual Characteristics Study was funded by Genentech Inc. The study was conducted between July 1992 and September 1993 in 65 PROS practices.
Subjects included girls 3 through 12 years of age who were being seen for a health supervision visit or for a problem that would require a complete physical examination.
Secondary sexual characteristics and menses in young girls seen in office practice: A study from the Pediatric Research in Office Settings network.
www.aap.org /pros/sscpubl2.htm   (354 words)

 ScienceDaily: A Key To Male Fertility
It is characterized by anatomical alterations: the maturation of primary sexual characteristics (penis, scrotum and testes) and the appearance of secondary sexual characteristics (hair growth, breaking of the voice, growth, etc).
Testosterone in particular is responsible for the development of secondary sexual characteristics in boys.
At the current time, mutations of the LH receptor are the only known causes of sexual precocity in boys, which shows the important role that this signaling pathway plays in the control of the endocrine system.
www.sciencedaily.com /releases/2007/03/070302082255.htm   (704 words)

 Disorders of Sexual Differentiation - New Treatments, January 2, 2007
In addition there is no development of second sexual characteristics, no breast development, no pubic hair, and you can see the somewhat abnormal positioning of the arms as well.
Other examples of the phenotype, this is an infant who has neck webbing again residua of the in utero cystic hygroma and there is some edema in the hands that are typical.
She has development of secondary sexual characteristics, but what’s missing here is pubic and axillary hair.
www.ccspublishing.com /journals5a/disorders_of_sexual_differentiatiation.htm   (668 words)

 Sexing Iguanas
Sexual maturity in iguanas is a function of size rather than age.
Two other male characteristics are a heftier, heavier body and a bulge near the base of the tail where the hemipenes are located.
Their heads are smaller and more streamlined, and lack the fatty deposits behind the eyes and the more pronounced jowls.
www.greenigsociety.org /malefemale.htm   (480 words)

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