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Testicular Toxicants
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 calipers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testicular Artery
The testicular artery (the male gonadal artery, also called the internal spermatic arteries in older texts) is a branch of the abdominal aorta that supplies blood to the testis. It is a paired artery, with one for each of the testes. It is the male equivalent of the ovarian artery. Because the testis is found in a different location than that of its female equivalent, it has a different course than the ovarian artery. They are two slender vessels of considerable length, and arise from the front of the aorta a little below the renal arteries. Each passes obliquely downward and lateralward behind the peritoneum, resting on the Psoas major, the right lying in front of the inferior vena cava and behind the middle colic and ileocolic arteries and the terminal part of the ileum, the left behind the left colic and sigmoid arteries and the iliac colon. Each crosses obliquely over the ureter and the lower part of the external iliac artery to reach the abdominal inguinal ring, through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Follicle-stimulating Hormone
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and luteinizing hormone (LH) work together in the reproductive system. Structure FSH is a 35.5 kDa glycoprotein heterodimer, consisting of two polypeptide units, alpha and beta. Its structure is similar to those of luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and human chorionic gonadotropin (hCG). The alpha subunits of the glycoproteins LH, FSH, TSH, and hCG are identical and consist of 96 amino acids, while the beta subunits vary. Both subunits are required for biological activity. FSH has a beta subunit of 111 amino acids (FSH β), which confers its specific biologic action, and is responsible for interaction with the follicle-stimulating hormone receptor. The sugar port ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germ Cell
Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embryonic development * Cereal germ, the reproductive part of a cereal grain * Tooth germ, an aggregation of cells that eventually forms a tooth * Germ theory of disease, which states that some diseases are caused by microorganisms * Germ (mathematics), an object in a topological space that captures local properties Art and media Music * Germs (band), an American punk rock band * Germ (musician), a stage name of Tim Wright * Germ (rapper), an American rapper affiliated with Suicideboys and Pouya * "Germs" (song), by "Weird Al" Yankovic * ''The Germ'' (album), by Victim's Family Others * "Germs" (''Invader Zim''), an episode of ''Invader Zim'' * ''The Germ'' (periodical), a British art magazine published in 1850 * The Germs (comics) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seminiferous Tubule
Seminiferous tubules are located within the testes, and are the specific location of meiosis, and the subsequent creation of male gametes, namely spermatozoa. Structure The epithelium of the tubule consists of a type of sustentacular cells known as Sertoli cells, which are tall, columnar type cells that line the tubule. In between the Sertoli cells are spermatogenic cells, which differentiate through meiosis to sperm cells. Sertoli cells function to nourish the developing sperm cells. They secrete androgen-binding protein, a binding protein which increases the concentration of testosterone. There are two types: convoluted and straight, convoluted toward the lateral side, and straight as the tubule comes medially to form ducts that will exit the testis. The seminiferous tubules are formed from the testis cords that develop from the primitive gonadal cords, formed from the gonadal ridge. Function Spermatogenesis, the process for producing spermatozoa, takes place in the semin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunica Albuginea Of Testis
The tunica albuginea is the fibrous tissue covering of the testis. It is a dense blue-grey membrane, composed of bundles of white fibrous connective tissue, from which it derives its name '' albuginea'', which interlace in every direction. Structure The tunica albuginea is a layer of fibrous tissue capsule covering the testis. It is covered by the tunica vaginalis, except at the points of attachment of the epididymis to the testis, and along its posterior border, where the spermatic vessels enter the gland. It is thicker than the tunica albuginea of the ovary. The tunica albuginea is applied to the tunica vasculosa over the glandular substance of the testis, and, at its posterior border, is reflected into the interior of the gland, forming an incomplete vertical septum, called the mediastinum testis (corpus Highmori). Additional images File:Gray1145.png, Transverse section through the left side of the scrotum and the left testis. File:Gray1114.png, Section of a genital cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejaculate
Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory 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. In rare cases, ejaculation occurs because of prostatic disease. Ejaculation may also occur spontaneously during sleep (a nocturnal emission or "wet dream"). ''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 the urethra. Phases Stimulation A usual precursor to ejaculation is the sexual arousal of the male, leading to the erection of the penis, though not every arousal nor erection leads to ejaculation. Penile sexual stimulation during masturbation or vaginal, anal, oral, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sertoli Cells
Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-stimulating hormone (FSH) secreted by the adenohypophysis and express FSH receptor on their membranes. History Sertoli cells are named after Enrico Sertoli, an Italian physiologist who discovered them while studying medicine at the University of Pavia, Italy. He published a description of his eponymous cell in 1865. The cell was discovered by Sertoli with a Belthle microscope which had been purchased in 1862. In the 1865 publication, his first description used the terms "tree-like cell" or "stringy cell"; most importantly, he referred to these as "mother cells". Other scientists later used Enrico's family name to label these cells in publications, beginning in 1888. As of 2006, two textbooks that are devoted specifically to the Sertoli cell ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanner Scale
The Tanner scale (also known as the Tanner stages or Sexual Maturity Rating (SMR)) is a scale of physical development in children, adolescents and adults. 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 development of pubic hair. This scale was first identified in 1969 by James Tanner, a British pediatrician, after a two-decade-long study following the physical changes in girls undergoing puberty. Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty. Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. In HIV treatment, the Tanner scale is used to determine which regimen to follow for pediatric or adolescent patients on antiretroviral thera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 Hertz, kilohertz (20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating Predation, prey and obstacles. History Acoustics, the science of sound, starts as far back as Pyth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orchidometer
An orchidometer (or orchiometer) is a medical instrument used to measure the volume of the testicles. The orchidometer was introduced in 1966 by Swiss pediatric endocrinologist Andrea Prader of the University of Zurich. It consists of a string of twelve numbered wooden or plastic beads of increasing size from about 1 to 25 millilitres. Doctors sometimes informally refer to them as "Prader's balls", "the medical worry beads", or the "endocrine rosary". The beads are compared with the testicles of the patient, and the volume is read off the bead which matches most closely in size. Prepubertal sizes are 1–3 ml, pubertal sizes are considered 4 ml and up and adult sizes are 15-25 ml. The orchidometer can be used to accurately determine size of testes. Discrepancy of testicular size with other parameters of maturation can be an important clue to various diseases. Small testes can indicate either primary or secondary hypogonadism. Testicular size can help distinguish between differen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellipsoid
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the zero set of a polynomial of degree two in three variables. Among quadric surfaces, an ellipsoid is characterized by either of the two following properties. Every planar cross section is either an ellipse, or is empty, or is reduced to a single point (this explains the name, meaning "ellipse-like"). It is bounded, which means that it may be enclosed in a sufficiently large sphere. An ellipsoid has three pairwise perpendicular axes of symmetry which intersect at a center of symmetry, called the center of the ellipsoid. The line segments that are delimited on the axes of symmetry by the ellipsoid are called the ''principal axes'', or simply axes of the ellipsoid. If the three axes have different lengths, the figure is a triaxial ellipsoid (r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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