Sexual organ in the context of "Sex characteristics"

The cervix (pl.: cervices) or uterine cervix (Latin: cervix uteri) is a dynamic fibromuscular sexual organ of the female reproductive system that connects the vagina with the uterine cavity. The human female cervix has been documented anatomically since at least the time of Hippocrates, over 2,000 years ago. The cervix is approximately 4 cm (1.6 in) long with a diameter of approximately 3 cm (1.2 in) and tends to be described as a cylindrical shape, although the front and back walls of the cervix are contiguous. The size of the cervix changes throughout a female's life cycle. For example, females in the fertile years of their reproductive cycle tend to have larger cervixes than postmenopausal females; likewise, females who have produced offspring have a larger cervix than those who have not.

In relation to the vagina, the part of the cervix that opens into the uterus is called the internal os while the opening of the cervix into the vagina is called the external os. Between those extremes is the conduit commonly called the cervical canal. The lower part of the cervix, known as the vaginal portion of the cervix (or ectocervix), bulges into the top of the vagina. The endocervix borders the uterus. The cervical conduit has at least two types of epithelium (lining): the endocervical lining is glandular epithelia that lines the endocervix with a single layer of column-shaped cells; while the ectocervical part of the conduit contains squamous epithelium. Squamous epithelia line the conduit with multiple layers of cells topped with flat cells. These two linings converge at the squamocolumnar junction (SCJ). This junction changes location dynamically throughout a female's life. The cervix is the organ that allows epithelia to flow from a female's uterus and out through her vagina at menstruation. Menstruation releases epithelia from a female’s uterus with every period of her fertile years, unless pregnancy occurs.

In many animals, a penis (/ˈpiːnɪs/; pl.: penises or penes) is the main male sexual organ used to inseminate females (or hermaphrodites) during copulation. Such organs occur in both vertebrates and invertebrates, but males do not bear a penis in every animal species. Furthermore, penises are not necessarily homologous.

The term penis applies to many intromittent organs, but not to all. As an example, the intromittent organ of most Cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata, there are morphological variants with specific terminology, such as hemipenes.

In male human anatomy, the foreskin, also known as the prepuce (/ˈpriːpjuːs/), is the double-layered fold of skin, mucosal and muscular tissue at the distal end of the human penis that covers the glans and the urinary meatus. The foreskin is attached to the glans by an elastic band of tissue, known as the frenulum. The outer skin of the foreskin meets with the inner preputial mucosa at the area of the mucocutaneous junction. The foreskin is mobile, fairly stretchable and sustains the glans in a moist environment. Except for humans, a similar structure known as a penile sheath appears in the male sexual organs of all primates and the vast majority of mammals.

In humans, foreskin length varies widely and coverage of the glans in a flaccid and erect state can also vary. The foreskin is fused to the glans at birth and is generally not retractable in infancy and early childhood. Inability to retract the foreskin in childhood should not be considered a problem unless there are other symptoms. Retraction of the foreskin is not recommended until it loosens from the glans before or during puberty. In adults, it is typically retractable over the glans, given normal development. The male prepuce is anatomically homologous to the clitoral hood in females. In some cases, the foreskin may become subject to a pathological condition.