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Sex Characteristics
Sexual characteristics are physical traits of an organism (typically of a sexually dimorphic organism) which are indicative of its biological sex. These can include sex organs used for reproduction and secondary sex characteristics which distinguish the sexes of a species, but which are not directly part of the reproductive system. Humans In humans, sex organs or primary sexual characteristics, which are those a person is born with, can be distinguished from secondary sex characteristics, which develop later in life, usually during puberty. The development of both is controlled by sex hormones produced by the body after the initial fetal stage where the presence or absence of the Y-chromosome and/or the SRY gene determine development. Hormones that express sexual differentiation in humans include: * estrogens * progesterone * androgens such as testosterone Typical sexual characteristics The following table lists the typical sexual characteristics in humans: Inverte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea. All types of organisms are capable of reproduction, growth and development, maintenance, and some degree of response to stimuli. Beetles, squids, tetrapods, mushrooms, and vascular plants are examples of multicellular organisms that differentiate specialized tissues and organs during development. A unicellular organism may be either a prokaryote or a eukaryote. Prokaryotes are represented by two separate domains – bacteria and archaea. Eukaryotic organisms are characterized by the presence of a membrane-bound cell nucleus and contain additional membrane-bound compartments called organelles (such as mitochondria in animals and plants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testicle
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosterone. Testosterone release is controlled by the anterior pituitary luteinizing hormone, whereas sperm production is controlled both by the anterior pituitary follicle-stimulating hormone and gonadal testosterone. Structure Appearance Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's anatomy. For 85% of men, the right testis hangs lower than the left one. Measurement and volume The volume of the testicle can be estimated by palpating it and comparing it to ellipsoids of known sizes. Another method is to use cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labia
The labia are part of the female genitalia; they are the major externally visible portions of the vulva. In humans, there are two pairs of labia: the ''labia majora'' (or the outer labia) are larger and thicker, while the '' labia minora'' are folds of skin between the outer labia. The labia surround and protect the clitoris and the openings of the vagina and the urethra. Etymology ''Labium'' (plural ''labia'') is a Latin-derived term meaning "lip". ''Labium'' and its derivatives (including labial, labrum) are used to describe any lip-like structure, but in the English language, ''labium'' often specifically refers to parts of the vulva. Anatomy The labia majora, also commonly called outer labia or outer lips, are lip-like structures consisting mostly of skin and adipose (fatty) tissue, which extend on either side of the vulva to form the pudendal cleft through the middle. The labia majora often have a plump appearance, and are thicker towards the anterior. The anterior juncti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seminal Vesicle
The seminal vesicles (also called vesicular glands, or seminal glands) are a pair of two convoluted tubular glands that lie behind the urinary bladder of some male mammals. They secrete fluid that partly composes the semen. The vesicles are 5–10 cm in size, 3–5 cm in diameter, and are located between the bladder and the rectum. They have multiple outpouchings which contain secretory glands, which join together with the vas deferens at the ejaculatory duct. They receive blood from the vesiculodeferential artery, and drain into the vesiculodeferential veins. The glands are lined with column-shaped and cuboidal cells. The vesicles are present in many groups of mammals, but not marsupials, monotremes or carnivores. Inflammation of the seminal vesicles is called seminal vesiculitis, most often is due to bacterial infection as a result of a sexually transmitted disease or following a surgical procedure. Seminal vesiculitis can cause pain in the lower abdomen, scrot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vas Deferens
The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube which exits the abdominal cavity through the inguinal canal. Etymology ''Vas deferens'' is Latin, meaning "carrying-away vessel"; the plural version is ''vasa deferentia''. ''Ductus deferens'' is also Latin, meaning "carrying-away duct"; the plural version is ''ducti deferentes''. Structure There are two vasa deferentia, connecting the left and right epididymis with the seminal vesicles to form the ejaculatory duct in order to move sperm. The (human) vas deferens measures 30–35 cm in length, and 2–3 mm in diameter. The vas deferens is continuous proximally with the tail of the epididymis. The vas deferens exhibits a tortuous, convoluted initial/proximal section (which measures 2–3 cm in length). Distally, it form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostate
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes and in microanatomy by zone. It is surrounded by an elastic, fibromuscular capsule and contains glandular tissue as well as connective tissue. The prostate glands produce and contain fluid that forms part of semen, the substance emitted during ejaculation as part of the male sexual response. This prostatic fluid is slightly alkaline, milky or white in appearance. The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. The prostatic fluid is expelled in the first part of ejaculate, together with most of the sperm, because of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corpus Cavernosum Penis
A corpus cavernosum penis (singular) (literally "cave-like body" of the penis, plural corpora cavernosa) is one of a pair of sponge-like regions of erectile tissue, which contain most of the blood in the penis during an erection. Such a corpus is homologous to the corpus cavernosum clitoridis in the female; the body of the clitoris that contains erectile tissue in a pair of corpora cavernosa with a recognisably similar structure. Anatomy The two corpora cavernosa and corpus spongiosum (also known as the ''corpus cavernosum urethrae'' in older texts and in the adjacent diagram) are three expandable erectile tissues along the length of the penis, which fill with blood during penile erection. The two corpora cavernosa lie along the penis shaft, from the pubic bones to the head of the penis, where they join. These formations are made of a sponge-like tissue containing trabeculae, irregular blood-filled spaces lined by endothelium and separated by septum of the penis. The mal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fallopian Tube
The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In other mammals they are only called oviducts. Each tube is a muscular hollow organ that is on average between 10 and 14 cm in length, with an external diameter of 1 cm. It has four described parts: the intramural part, isthmus, ampulla, and infundibulum with associated fimbriae. Each tube has two openings a proximal opening nearest and opening to the uterus, and a distal opening furthest and opening to the abdomen. The fallopian tubes are held in place by the mesosalpinx, a part of the broad ligament mesentery that wraps around the tubes. Another part of the broad ligament, the mesovarium suspends the ovaries in place. An egg cell is transported from an ovary to a fallopian tube where it may be fertilized in the ampulla of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uterus
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uterus is a hormone-responsive sex organ that contains glands in its lining that secrete uterine milk for embryonic nourishment. In the human, the lower end of the uterus, is a narrow part known as the isthmus that connects to the cervix, leading to the vagina. The upper end, the body of the uterus, is connected to the fallopian tubes, at the uterine horns, and the rounded part above the openings to the fallopian tubes is the fundus. The connection of the uterine cavity with a fallopian tube is called the uterotubal junction. The fertilized egg is carried to the uterus along the fallopian tube. It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagina
In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. At the deep end, the cervix (neck of the uterus) bulges into the vagina. The vagina allows for sexual intercourse and birth. It also channels menstrual flow, which occurs in humans and closely related primates as part of the menstrual cycle. Although research on the vagina is especially lacking for different animals, its location, structure and size are documented as varying among species. Female mammals usually have two external openings in the vulva; these are the urethral opening for the urinary tract and the vaginal opening for the genital tract. This is different from male mammals, who usually have a single urethral opening for both urination and reproduction. The vaginal opening is much larger than the nearby urethral openi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clitoris
The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), above the opening of the urethra. Unlike the penis, the male homologue (equivalent) to the clitoris, it usually does not contain the distal portion (or opening) of the urethra and is therefore not used for urination. In most species, the clitoris lacks any reproductive function. While few animals urinate through the clitoris or use it reproductively, the spotted hyena, which has an especially large clitoris, urinates, mates, and gives birth via the organ. Some other mammals, such as lemurs and spider monkeys, also have a large clitoris. The clitoris is the human female's most sensitive erogenous zone and generally the primary anatomical source of human female sexual pleasure. In humans and other mammals, it develops from an outgrowth in the em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genitalia
A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, are called the ''primary sex organs''. All others are called ''secondary sex organs'', divided between the external sex organs—the genitals or external genitalia, visible at birth in both sexes—and the internal sex organs. Mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. The flowers of flowering plants produce pollen and egg cells, but the sex organs themselves are inside the gametophytes within the pollen and the ovule. Coniferous plants likewise produce their sexually reproductive structures within the gametophytes contained within the cones and pollen. The cones and pollen are not themselves sexual organs. Terminology The ''primary sex organs'' are the gonads, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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