Penis: The external reproductive organ of males. It is composed of a mass of erectile tissue enclosed in three cylindrical fibrous compartments. Two of the three compartments, the corpus cavernosa, are placed side-by-side along the upper part of the organ. The third compartment below, the corpus spongiosum, houses the urethra.Penile Neoplasms: Cancers or tumors of the PENIS or of its component tissues.Penile Erection: The state of the PENIS when the erectile tissue becomes filled or swollen (tumid) with BLOOD and causes the penis to become rigid and elevated. It is a complex process involving CENTRAL NERVOUS SYSTEM; PERIPHERAL NERVOUS SYSTEMS; HORMONES; SMOOTH MUSCLES; and vascular functions.Erectile Dysfunction: The inability in the male to have a PENILE ERECTION due to psychological or organ dysfunction.Clitoris: An erectile structure homologous with the penis, situated beneath the anterior labial commissure, partially hidden between the anterior ends of the labia minora.Penile Induration: A condition characterized by hardening of the PENIS due to the formation of fibrous plaques on the dorsolateral aspect of the PENIS, usually involving the membrane (tunica albuginea) surrounding the erectile tissue (corpus cavernosum penis). This may eventually cause a painful deformity of the shaft or constriction of the urethra, or both.Balanitis: Inflammation of the head of the PENIS, glans penis.Priapism: A prolonged painful erection that may lasts hours and is not associated with sexual activity. It is seen in patients with SICKLE CELL ANEMIA, advanced malignancy, spinal trauma; and certain drug treatments.Scrotum: A cutaneous pouch of skin containing the testicles and spermatic cords.Penile Prosthesis: Rigid, semi-rigid, or inflatable cylindric hydraulic devices, with either combined or separate reservoir and pumping systems, implanted for the surgical treatment of organic ERECTILE DYSFUNCTION.Urologic Surgical Procedures, Male: Surgery performed on the male genitalia.Genitalia, Male: The male reproductive organs. They are divided into the external organs (PENIS; SCROTUM;and URETHRA) and the internal organs (TESTIS; EPIDIDYMIS; VAS DEFERENS; SEMINAL VESICLES; EJACULATORY DUCTS; PROSTATE; and BULBOURETHRAL GLANDS).Circumcision, Male: Excision of the prepuce of the penis (FORESKIN) or part of it.Tuberculosis, Male Genital: MYCOBACTERIUM infections of the male reproductive tract (GENITALIA, MALE).Hypospadias: A birth defect due to malformation of the URETHRA in which the urethral opening is below its normal location. In the male, the malformed urethra generally opens on the ventral surface of the PENIS or on the PERINEUM. In the female, the malformed urethral opening is in the VAGINA.Copulation: Sexual union of a male and a female in non-human species.Penile Implantation: Surgical insertion of cylindric hydraulic devices for the treatment of organic ERECTILE DYSFUNCTION.Genital Diseases, Male: Pathological processes involving the male reproductive tract (GENITALIA, MALE).Genitalia: The external and internal organs related to reproduction.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Spiders: Arthropods of the class ARACHNIDA, order Araneae. Except for mites and ticks, spiders constitute the largest order of arachnids, with approximately 37,000 species having been described. The majority of spiders are harmless, although some species can be regarded as moderately harmful since their bites can lead to quite severe local symptoms. (From Barnes, Invertebrate Zoology, 5th ed, p508; Smith, Insects and Other Arthropods of Medical Importance, 1973, pp424-430)Primula: A plant genus of the family PRIMULACEAE. It can cause CONTACT DERMATITIS. SAPONINS have been identified in the root.Cyprinodontiformes: An order of fish with eight families and numerous species of both egg-laying and livebearing fish. Families include Cyprinodontidae (egg-laying KILLIFISHES;), FUNDULIDAEl; (topminnows), Goodeidae (Mexican livebearers), Jenynsiidae (jenynsiids), Poeciliidae (livebearers), Profundulidae (Middle American killifishes), Aplocheilidae, and Rivulidae (rivulines). In the family Poeciliidae, the guppy and molly belong to the genus POECILIA.Insemination: The deposit of SEMEN or SPERMATOZOA into the VAGINA to facilitate FERTILIZATION.Cephalopoda: A class in the phylum MOLLUSCA comprised of SQUID; CUTTLEFISH; OCTOPUS; and NAUTILUS. These marine animals are the most highly organized of all the mollusks.Drowning: Death that occurs as a result of anoxia or heart arrest, associated with immersion in liquid.Swimming PoolsViviparity, Nonmammalian: The capability of bearing live young (rather than eggs) in nonmammalian species. Some species of REPTILES and FISHES exhibit this.Near Drowning: Non-fatal immersion or submersion in water. The subject is resuscitable.Ovotesticular Disorders of Sex Development: Conditions of sexual ambiguity in which the individual possesses gonadal tissues of both sexes, tissues from the OVARY and the TESTIS. There can be a testis on one side and an ovary on the other (lateral), or there may be combined ovarian and testicular tissue (ovotestes) on each side (bilateral). The karyotype may be 46,XX; 46,XY; or a mosaic of 46,XX/46,XY. These disorders have historically been called true hermaphroditism.Foreskin: The double-layered skin fold that covers the GLANS PENIS, the head of the penis.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Skin Physiological Phenomena: The functions of the skin in the human and animal body. It includes the pigmentation of the skin.Skin Absorption: Uptake of substances through the SKIN.Erotica: Literary or artistic items having an erotic theme. It refers especially to books treating sexual love in a sensuous or voluptuous manner. (Webster, 3d ed)Arousal: Cortical vigilance or readiness of tone, presumed to be in response to sensory stimulation via the reticular activating system.Horseshoe Crabs: An arthropod subclass (Xiphosura) comprising the North American (Limulus) and Asiatic (Tachypleus) genera of horseshoe crabs.Photoreceptor Cells: Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.KentuckySuperstitions: A belief or practice which lacks adequate basis for proof; an embodiment of fear of the unknown, magic, and ignorance.Supreme Court Decisions: Decisions made by the United States Supreme Court.Decision Making: The process of making a selective intellectual judgment when presented with several complex alternatives consisting of several variables, and usually defining a course of action or an idea.Middle East: The region of southwest Asia and northeastern Africa usually considered as extending from Libya on the west to Afghanistan on the east. (From Webster's New Geographical Dictionary, 1988)Kidney Transplantation: The transference of a kidney from one human or animal to another.Liver Transplantation: The transference of a part of or an entire liver from one human or animal to another.Bombs: A weapon designed to explode when deployed. It frequently refers to a hollow case filled with EXPLOSIVE AGENTS.Physicians, Women: Women licensed to practice medicine.Sexism: Prejudice or discrimination based on gender or behavior or attitudes that foster stereotyped social roles based on gender.Hand: The distal part of the arm beyond the wrist in humans and primates, that includes the palm, fingers, and thumb.Sexual Maturation: Achievement of full sexual capacity in animals and in humans.Puberty: A period in the human life in which the development of the hypothalamic-pituitary-gonadal system takes place and reaches full maturity. The onset of synchronized endocrine events in puberty lead to the capacity for reproduction (FERTILITY), development of secondary SEX CHARACTERISTICS, and other changes seen in ADOLESCENT DEVELOPMENT.