The Male Reproductive System

The Male Reproductive System

The male reproductive system is made up two main parts.

1.           The External

2.           The internal parts

The External Organs

1. The Penis

It has its root in the perineum with the lower 2/3rd of the body suspended outside in front of the scrotal sac. It is made up of three bundles of spong-like erectitle tissues:

1.           2 the corporal cavernosa on the lateral columns in front of the urethra

2.           The corpus spongiosum on the posterior column which contains the urethra enclosed in a firm sheath of firm tissue with rich blood supply and covered with the skin. The skin continues with the scrotum and the groins. The skin double fold backwards on itself at the glans penis to form the prepuce (foreskin) which is usually removed during circumcision. The penis transmites a portion of the urethra which acts as a passage for semen as well as excretion of urine… During sexual excitement the pe nis becomes larger, rounder, firmer and erect to be able to penetrate and deposit semen near the cervix. Stimulation of the nervous system increases blood supply to the organ.

This erections tart at puberty and may result in wet dream in adolescent boy. There is a small sphincter in the urethra which prevent semen from entering the bladder and urine from the urethra mixing with the semen during intercourse.

2. The Scrotum

It is a sensitive pouch-like sac covered with wrinkled skin and hair from which the penis hangs. It lies in front of the thighs, behind the penis and is thickly pigmented. The scrotum is divided by a fibrous septum called Dartos muscle into two cavities each of which contain a testis epididymis and initial portion of the vas deference. The muscles contract in cold weather and relax in hot weather to ensure normal temperature around the testes. Next to the clartos muscle lies the cremaster muscle and fascia. It protects the testes from injuries.

The Internal Organs

1. The Testes

The testes are the male reproductive glands (Gonads), equivalent to the female ovaries. They are formed in the fetal abdomen at the lumber region just below the kidneys at about 28^th week of gestation. The testes descend into the scrotum via the right and left inguinal canal, toward the end of pregnancy. They are suspended by spermatic ducts. The testis is ovoid in shape & white in colour.

Size: 4-4.5cm long, 2.5cm wide 3cm thick and 10-14gm ormore in weight, depending on the heftiness of the individual man structure. Each testis is surrounded by 3 coverings of glandula tissue.

1.           Tunica Vaginalis: This is the thick outer covering and is adouble fold of a down growth of the abdominal and pelvic peritoneum brought down with the descending testis when it descends. The visceral layer surrounds the testes while the parietal lines the Germaters muscle.

2.           Tunica Albuginea: This is a fibrous tissue coat surroundingthe testes under the vaginalis. Ingrowths of albuginea form septa dividing the glandular tissue into 200-400 lobules. Each contains convulated seminiferous tubules lined with germinal epithelium which produce sperm (Spermatogenesis) from puberty. Surrounding the tabula are connective tissue stroma which contains cluders dendox cells (Leydig cells) cells which secrete testosterone.

3.           Tunica Vasculosa: This consists of network of capillariessupported by delicate connective tissues. They surround each lobule of the testes. The testes must be kept below body temperature in order to function properly, hence they are situated outside the body. Inflammation of the testis is known as Ochitis.

Cryptorchidism: Complete failure of the testes to descend into thescrotum. Such testes are destroyed due to high body temperature.

2. The Epididymis

This is a fine convoluted tubule about 6 metre in length connecting the testis and the vas defense. It is found at the posterior aspect of the testis. It produces substance which stimulates the development of the sperm. The sperms are stored here to become mature and motile

3. Vas Deferens

A continuation of the epididymis, commences at the tail and, passes upwards behind the testis through the inguinal canal and ascends medially towards the posterior wall of the bladder; enter the pelvic cavity where it connects with the seminal duct. These are the tubes ligated during vasectomy; it is about 450cmlong. The vas deferens duct is surrounded by smooth muscle the peristaltic contraction of the smooth muscle tissue help propel sperm cells through the duct.

4. Seminal Vesicles

These are small irregular Pyramid shaped sacs lying between the base of the bladder and the rectum. They are about 5cm long. They are composed of columnar epithelium, muscle and fibrous tissues. They secrete yellowish fluids which is an essential component of seminal fluid. Each vesicle opens into the seminal duct which joins the vas deferens on the corresponding side of the ejaculatory duct. The fluid contains fructose and other nutrients to nourish the sperm. Forms nutrients to nourish the sperm constitute about 60% of the semen and give it its co lour.

5. Ejaculatory Ducts

They are two small muscular ducts about 2cm long. Pass through the prostate gland and connects with the vas deferens and opens into the urethra. They carry the spermatozoa and seminal fluid to the urethra.

6. Prostate Gland

Is a cone shaped structure, about the size of a walnut.4cm long, 3cm wide, 2cm deep and 8g in weight. It lies below the bladder, surrounding the upper part of the urethra in direct contact with the neck of bladder. It is composed of glandular tissue and involuntary (Columnar epithelium) muscle enclosed in fibrous capsule. It secretes alkaline fluid which makes up 30% of semen. It is added to the sperm, and the muscle fiber aids ejaculation of the sperm. The fluid neutralizes the acidity of the vagina during intercourse. It gives the characteristic odour. Enlargement of prostate gland in old men causes urine retention.

7. Cowper’s Glands (Bulbo Urethral Glands)

They are two small glands about the size of a cowpea, yellow in colour and lie below the prostate gland. The ducts about 3cm long open into the urethra before reaching the penile portion. The secretion is alkaline in nature and is added to the seminal fluids and also help to lubricate the penis during sexual activities.

8. The Urethra

Is a tube, about 8 cm long, travels from the bladder to the tip of the penis. Urine passes through it as well as a passage for semen during sexual intercourse. The muscle at the neck of the bladder closes it up to prevent semen from entering the bladder during sexual intercourse.