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A testicle or testis 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.
An androgen is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands.
Seminiferous tubules are located within the testes, and are the specific location of meiosis, and the subsequent creation of male gametes, namely spermatozoa.
The rete testis is an anastomosing network of delicate tubules located in the hilum of the testicle that carries sperm from the seminiferous tubules to the efferent ducts. It is the homologue of the rete ovarii in females. Its function is to provide a site for fluid reabsorption.
In biology, a tubule is a general term referring to small tube or similar type of structure. Specifically, tubule can refer to:
Sex cord–gonadal stromal tumour is a group of tumors derived from the stromal component of the ovary and testis, which comprises the granulosa, thecal cells and fibrocytes. In contrast, the epithelial cells originate from the outer epithelial lining surrounding the gonad while the germ cell tumors arise from the precursor cells of the gametes, hence the name germ cell. In humans, this group accounts for 8% of ovarian cancers and under 5% of testicular cancers. Their diagnosis is histological: only a biopsy of the tumour can make an exact diagnosis. They are often suspected of being malignant prior to operation, being solid ovarian tumours that tend to occur most commonly in post menopausal women.
The 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 male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the body and within the pelvis.
A spermatogonium is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testis.
Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The genital papilla is a small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish can often be determined by the shape of its papilla.
Embryonal carcinoma is a relatively uncommon type of germ cell tumour that occurs in the ovaries and testes.
The epoophoron or epoöphoron is a remnant of the mesonephric tubules that can be found next to the ovary and fallopian tube.
In embryogenesis, the sex cords are structures that develop from the genital ridges that further differentiate based on an embryo's sex. After sexual differentiation, at day 49, the sex cords in females become the cortical cords, also called secondary cords. After further development, they become the ovarian follicles. The sex cords in males become the testis cords by the action of the testis-determining factor protein, which helps to develop and nourish the Sertoli cells.
The genital ridge is the precursor to the gonads. The genital ridge initially consists mainly of mesenchyme and cells of underlying mesonephric origin. Once oogonia enter this area they attempt to associate with these somatic cells. Development proceeds and the oogonia become fully surrounded by a layer of cells.
Simple cuboidal epithelium is a type of epithelium that consists of a single layer of cuboidal (cube-like) cells which have large, spherical and central nuclei.
The tubuli seminiferi recti are structures in the testicle connecting the convoluted region of the seminiferous tubules to the rete testis, although the tubuli recti have a different appearance distinguishing them from these two structures.
The development of the reproductive system is the part of embryonic growth that results in the sex organs and contributes to sexual differentiation. Due to its large overlap with development of the urinary system, the two systems are typically described together as the urogenital or genitourinary system.
The development of the gonads is part of the prenatal development of the reproductive system and ultimately forms the testes in males and the ovaries in females. The gonads initially develop from the mesothelial layer of the peritoneum.
Scrotalultrasound is a medical ultrasound examination of the scrotum. It is used in the evaluation of testicular pain, and can help identify solid masses.
References
- ↑ Development of the Ovaries
- ↑ Definition: rete ovarii from Online Medical Dictionary
- ↑ Odend'hal, Stewart; Wenzel, James Guthrie Wheeler; Player, Emory Craig (September 1986). "The rete ovarii of cattle and deer communicates with the uterine tube". The Anatomical Record. 216 (1): 40–43. doi:10.1002/ar.1092160107. ISSN 0003-276X. PMID 3767001. S2CID 23132112.
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