DihydrotestosteroneDihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues including the prostate gland, seminal vesicles, epididymides, skin, hair follicles, liver, and brain. This enzyme mediates reduction of the C4-5 double bond of testosterone. DHT may also be synthesized from progesterone and 17α-hydroxyprogesterone via the androgen backdoor pathway in the absence of testosterone.
MonotremeMonotremes (ˈmɒnətriːmz) are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types. Although they are different from almost all mammals in that they lay eggs, like all mammals, the female monotremes nurse their young with milk.
Ejaculatory ductThe ejaculatory ducts (ductus ejaculatorii) are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the urethra above the seminal colliculus. During ejaculation, semen passes through the prostate gland, enters the urethra and exits the body via the urinary meatus. Ejaculation Ejaculation occurs in two stages, the emission stage and the expulsion stage.
Rectal examinationDigital rectal examination (DRE), also known as a prostate exam (palpatio per anum (PPA)), is an internal examination of the rectum performed by a healthcare provider. Prior to a 2018 report from the United States Preventive Services Task Force, a digital exam was a common component of annual exams for older men, as it was thought to be a reliable screening test for prostate cancer. This examination may be used: for the diagnosis of prostatic disorders, benign prostatic hyperplasia and the four types of prostatitis.
CloacaIn non-human animal anatomy, a cloaca (kloʊˈeɪkə ), : cloacae (kloʊˈeɪsi or kloʊˈeɪki ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles), have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation.
Sertoli cellSertoli 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. Sertoli cells are named after Enrico Sertoli, an Italian physiologist who discovered them while studying medicine at the University of Pavia, Italy.
UrethraThe urethra (from Greek οὐρήθρα – ourḗthrā; : urethras or urethrae) is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus. Females use their urethra only for urinating, but males use their urethra for both urination and ejaculation.
Development of the urinary systemThe development of the urinary system begins during prenatal development, and relates to the development of the urogenital system – both the organs of the urinary system and the sex organs of the reproductive system. The development continues as a part of sexual differentiation. The urinary and reproductive organs are developed from the intermediate mesoderm. The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before birth.
HypospermiaHypospermia is a condition in which a man has an unusually low ejaculate (or semen) volume, less than 1.5 mL. It is the opposite of hyperspermia, which is a semen volume of more than 5.5 mL. It should not be confused with oligospermia, which means low sperm count. Normal ejaculate when a man is not drained from prior sex and is suitably aroused is around 1.5–6 mL, although this varies greatly with mood, physical condition, and sexual activity. Of this, around 1% by volume is sperm cells. The U.S.
AspermiaAspermia is the complete lack of semen with ejaculation (not to be confused with azoospermia, the lack of sperm cells in the semen). It is associated with infertility. One of the causes of aspermia is retrograde ejaculation, because of that the sperm is kept into the bladder and the final ejaculate is 0 mL. It can be brought on by excessive drug use, or as a result of prostate surgery. It can also be caused by alpha blockers such as tamsulosin and silodosin.
