3D Medical Animation male accessory gland

Male accessory glands (MAG) in humans are the seminal vesicles,

prostate gland 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 physi ...

, and the

bulbourethral glands The bulbourethral glands or Cowper's glands (named for English anatomist William Cowper) are two small exocrine glands in the reproductive system of many male mammals (of all domesticated animals, they are absent only in dogs). They are homolog ...

(also called Cowper's glands). In insects, male accessory glands produce products that mix with the sperm to protect and preserve them, including seminal fluid proteins. Some insecticides can induce an increase in the protein content of the male accessory glands of certain types of insects. This has the unintended effect of increasing the number of offspring they produce. These glands secrete fluid for nourishment of

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, ...

Accessory glands

The male accessory glands are the ampullary gland, seminal vesicles, prostate,

bulbourethral gland The bulbourethral glands or Cowper's glands (named for English anatomist William Cowper) are two small exocrine glands in the reproductive system of many male mammals (of all domesticated animals, they are absent only in dogs). They are homolo ...

, and

urethral glands The urethral or periurethral glands (also Littré glands after Alexis Littré) are glands that branch off the wall of the urethra of mammals. The glands secrete mucus and are most numerous in the section of the urethra that runs through the penis ...

. The products of these glands serve to nourish and activate the

spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromos ...

, to clear the urethral tract prior to

ejaculation 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 compo ...

, serve as the vehicle of transport of the spermatozoa in the female tract, and to plug the female tract after placement of spermatozoa to help ensure

fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Pro ...

. Although the glands are usually described as being branched tubular or branched tubuloalveolar, they vary in their organization and in their distribution in different species.

Ampullary glands

Each of these branched tubular glands lined by simple columnar

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

is an enlargement of the vas deferens in its terminal portion. These are typical tubular glands in

ruminants Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...

, horses and dogs; absent in the cat and poorly developed in boars. The function of the white serous secretion is not known.

Seminal vesicles

The secretory endpieces of these glands are lined with simple columnar

; the main ducts are lined with stratified columnar epithelium. These glands do not occur in carnivores, but are present in some form in horses,

and swine. Seminal fluid, the product of this gland, serves as a vehicle for the transport of

Prostate gland

Grossly the prostate gland can be divided into two parts: the body and the disseminate part. Low cuboidal to low columnar

provides the lining for this compound, tubuloalveolar gland which consists primarily of serous secretory end pieces. The secretion of this gland is more serous in dogs and more mucous in bulls. It serves to promote the movement of

and to form a

vaginal plug A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς ''sphragis'', "a seal"), is gelatinous secretion used in the mating of some species. It is deposited by a male into a female g ...

. Additionally, in bulls, the secretion contains high amounts of

fructose Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorb ...

and

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...

. Concretions may be present in the secretory end pieces as well as parts of the duct system. The prostate and Cowper's glands are the only male accessory glands in marsupials.

Bulbourethral glands

The lining of these paired, compound, tubuloalveloar glands is simple columnar

. A capsule of dense

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

contains some

smooth muscle Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...

as well as

skeletal muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of m ...

of the

bulbospongiosus The bulbospongiosus muscle (bulbocavernosus in older texts) is one of the superficial muscles of the perineum. It has a slightly different origin, insertion and function in males and females. In males, it covers the bulb of the penis. In fem ...

and urethral muscles. All domestic species have these glands except the dog, and their

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

secretion serves to clear the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') 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 ...

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...

and to lubricate it and the

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 ...

. The product may also serve as an energy source for the

Urethral glands

In some species, branched tubular

mucous glands Mucous gland, also known as muciparous glands, are found in several different parts of the body, and they typically stain lighter than serous glands during standard histological preparation. Most are multicellular, but goblet cells are single-ce ...

are found along the length of the

, especially dorsal to the lumen of the urethra. The exact function of their product is not clear.

Distribution in insects

The male accessory gland is also prevalent in some species of butterflies and moths. An example is the cotton leafworm, or '' Spodoptera litura'', in which the males transfer MAG to the females during copulation. This results in a wide range of post-mating behavior in the females, the most noteworthy being the decrease in sexual receptivity in the females. This helps to assure that no other males will mate with that female, allowing her eggs to be fertilized by the current male's own sperm.

References

{{DEFAULTSORT:Male Accessory Gland Animal reproductive system