Understanding the Male Reproductive System
General Characteristics
Ontogenesis is a branch of biology that concerns the study of living beings from their fertilization until birth, also called embryology.
Reproduction is a fundamental characteristic of all living things, particularly humans, and has enabled and perpetuated evolution as biological species throughout the history of life.
Humans reproduce sexually, possessing gonads, organs specialized for producing gametes or sex cells. These unite to form the egg cell, called a zygote, from which the new being develops.
Male Reproductive Organs
The male reproductive system consists of the male gonads (testes), the spermatic ducts, glands, and the attached penis.
The normal functioning of these organs determines the production of male sex cells (sperm) and their delivery to the female genitalia.
1. Testes
The testes are two glands contained in a pouch of skin called the scrotum or scrotal sac. In humans, as in most mammals, the testes form within the abdomen near the kidneys. They remain in this site until shortly before or after birth, then descend into the scrotum through an opening in the abdominal wall, the inguinal canal. The scrotum serves as a cooling unit, keeping the sperm at 2 to 4°C lower than body temperature, as they would not form at body temperature.
1.1 Structure
Each testis is covered by a membrane, the tunica albuginea, which extends to the interior, forming walls that divide the testis into approximately 250 compartments called lobes or loculi.
Each lobe contains 1 to 3 tubules called seminiferous tubules, formed by germ cells that give rise to spermatogonia and sperm, and supporting cells (Sertoli cells) derived from the surface epithelium of the gland. Sertoli cells secrete hormones between 12 and 14.
These tubules join the rete testis, which in turn enters the efferent ductules that carry sperm to the common channel called the epididymis.
The sperm count present in only a few drops of semen is extraordinary: 100 to 200 million per cubic millimeter of semen, and approximately 5 million per drop.
The testicle is a mixed gland, secreting through gonadotrophic hormones secreted by the pituitary gland: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH determines the maturation of sperm, and LH stimulates the interstitial cells to secrete the male hormone testosterone, responsible for stimulating organic and psychic changes related to the development of secondary sexual characteristics, such as:
- Pubic, underarm, and facial hair.
- Development of the vocal cords, resulting in a deeper voice.
- Development of musculature.
- Enhanced growth of the body.
2. Spermatic Ducts
The spermatic ducts are the channels that carry sperm from the testicles to the outside, to be deposited in the female reproductive organs. These include the seminiferous tubules, efferent ducts, epididymis, vas deferens, ejaculatory ducts, and urethra.
a) Epididymis
The epididymis is a completely coiled tube of 5 to 6 cm in length, in which sperm cells complete their maturation and storage. The epididymis and spermatic duct empty into the vas deferens.
b) Vas Deferens
Also called the ductus deferens, it extends from the scrotum through the inguinal canal, into the pelvic cavity, and empties into the ejaculatory duct.
c) Ejaculatory Ducts
These ducts pass through the prostate and unite to form the urethra.