[Biology Class Notes] on Ejaculatory Duct Pdf

Ejaculatory duct definition is given as: It is one of two hollow tubes created by the union of the ductus deferens ampulla and the seminal vesicle excretory duct. The ducts are responsible for combining sperm in the ampulla with fluids secreted by the seminal vesicles and transferring these substances to the prostate gland. They open into the urethra about halfway through the prostate gland or the prostate ejaculatory duct obstruction.

About Ejaculatory Duct

Every ejaculatory duct is up to 2 centimetres in length and is created when the duct merges the seminal vesicle with the vas deferens. These ducts pass through the prostate at this stage and drain into the urethra of colliculus seminalis at the other end.

Semen flows through every ejaculatory duct during ejaculation, travelling through the penis to exit from the body.

The male and female ejaculatory duct representations are given below.

One ejaculatory duct or both may become obstructed in the congenital (from birth) or acquired pathological complication called ejaculatory duct obstruction. When both the ducts are obstructed, patients are more likely to experience symptoms such as azoospermia (low sperm count) and infertility or aspermia (absence of sperm). Transurethral resection is given as the surgical procedure, which may be used to open the ducts; its goal is to make the regular ejaculation flow possible again.

Benign prostatic hyperplasia, which refers to the abnormal increase in prostate size, is the other condition, which can affect the ejaculatory ducts. Though this condition is correctable by the surgery, an ejaculatory duct could be damaged in the process by causing retrograde ejaculation.

Steps of Ejaculation

Generally, an ejaculation follows different steps:

The phases are similar in both men and women. However, the excitation phase available in men is very fast, and in women, it is not so immediate (normally). The plateau phase in the men is shorter also. The refractory period will be shorter in the women compared to the men. In addition, women may have multiorgasms due to this shorter refractory period.

After the ejaculation in the vagina, most of the spermatozoa have been destroyed. Estradiol induces changes in the cervix, which will allow the entrance of spermatozoa.

Ejaculatory Duct Function

Ejaculation

Let us look at the male ejaculatory duct function, prostate and ejaculatory duct in detail.

Ejaculatory duct obstruction takes place in two stages:

• the emission stage and

• the expulsion stage.

Many structures of the ejaculatory duct are involved in the emission stage; contractions of the seminal vesicles, prostate gland, bulbourethral gland, and vas deferens force fluids into the prostatic urethra. The semen can be stored here until the ejaculation takes place. The seminal fluid trapped in the prostatic urethra is propelled through the penile urethra and expelled through the urinary meatus by muscles at the base of the penis contracting. The ejaculate is expelled in the spurts because of the movement of the muscles that propel it. These specific muscle contractions are related to the sensations of the orgasm for males.

Sperm is produced in the testes and enters into the ejaculatory ducts through the vas deferens. As it passes by the seminal vesicles, a fluid, which is rich in fructose, combines with the sperm. This addition will nourish the sperm to keep it motile and active. The seminal fluid then travels down the ejaculatory duct into the prostate gland, where it can be supplemented with alkaline prostatic fluid. This addition will provide the odour and texture associated with the semen. The alkalinity of the prostatic fluid helps to neutralise the acidity of the female vaginal tract, allowing sperm to survive in this harsh environment.

Now, semen is a fructose-rich, alkaline fluid containing sperm because it enters the bulbourethral glands down to the prostate. The bulbourethral glands secrete fewer amounts of clear fluid into the urethra prior to the ejaculate is expelled. The functions of this fluid are not totally known but are suggested to aid in lubricating the male urethra in the semen preparation during ejaculation. The amount of semen, which is produced and expelled during the ejaculation, corresponds to the length of time that the male is aroused sexually before the ejaculation takes place. In general, the longer the period of arousal, the larger the seminal fluid amount.

Orgasm and ejaculation may take place simultaneously. However, they are not coupled in that one may take place without the other. For example, a man can have a dry orgasm (termed as Retrograde ejaculation); there exists no expulsion of ejaculate; however, still, the man experiences orgasm. In addition, paraplegics can ejaculate the seminal fluid but cannot experience the orgasm sensation.

Clinical Relevance

Ejaculatory Duct Obstruction

Ejaculatory duct obstruction is given as a congenital or acquired pathological condition in which either one or both ejaculatory ducts are obstructed. In the case where both ejaculatory ducts are obstructed, this specific illness presents with aspermia and male infertility symptoms.