Production of sperms.

2. Secretion of Testosterone hormone, which causes the secondary male characteristics to appear at puberty.

B. The two epididymis:

Each testis leads to a group of cumulated tubes called epididymis, the latter fuses in the vas deferens.

C. The two vas deferens:

Each vas deferens transports sperms from the epididymis to a seminal vesicle.

D. The two seminal vesicles:

In which the sperms are stored until they leave the body.

E. Prostate gland and Cowper’s glands:

They secrete a sugary fluid (which nourishes sperms) and alkaline fluid to neutralize the acidity of the urethera. Since the neutral medium suits the passage of the sperms in it, therefore the alkaline fluid passes in the urethera just before the sperms.

F. The penis:

Is an organ that consists of a fibrous tissue. The urethera passes through it, through which both urine and sperms are expelled individually.

Study of a T.S. of testis:

The testis is built up of:

Seminiferous tubules among them these are interstitial cells which secrete the testosterone hormone.

Inside each tubule these are sertoli cells which secrete fluid to nourish the sperms inside the testis, they also have immunization function.

Each tubule is lined internally with diploid primary germ cells (2N), they are dividing, giving sperms finally.

Phases of spermatogenesis:

There are four main phases:

1. Multiplication phase:

In which the (2N) primary germ cells divide mitotically several times

Giving great number of (2N) spermatogonia cells.

1. Growth phase:

In which the spermatogonia cells store an amount of food and are transformed into (2N) primary spermatocytes.

1. Maturation phase:

In which the (2N) primary spermatocytes undergo meiosis(I) to form (N) secondary spermatocytes which undergo meiosis(II) giving (N) haploid spermatids. (The number of chromosomes is reduced to its half during the maturation phase).

1. Metamorphosis phase:

In which the (N) spermatids are converted into (N) sperms.

Stages of Spermatogenesis

The structure of a sperm:

1. The head:

It contains the nucleus with 23 chromosomes. There is an acrosome in the forehead which secretes the Hyaluronic enzyme that dissolves a part of the ovum membrane, to facilitate its penetration process.

2. The neck:

It contains two centrioles which play an important role in the division of the fertilized ovum.

3. The midpiece:

It contains mitochondria which supply energy for sperm movement.

4. The tail:

It consists of an axis which ends with caudal piece. It helps the sperm to move.

The Human Female Genital System

It consists of two ovaries, two oviducts, the uterus, and the vagina. This system produces the ova and the female sex hormones, besides providing a safe place for completion of fertilization, and embryonic development till birth.

The organs of this system lie behind the urinary bladder in the pelvic region. They are firmly connected in this position with elastic ligaments which allows its expansion during pregnancy.

1. The two ovaries:

They lie on the sides of the pelvic cavity. Each ovary has an oval shape. It equals in size a peeled almond. During childhood, each ovary contains several thousands of ova in various stages of development. After maturity, about 400 of these ova only, will mature during the thirty years of active reproductive life (fecundity years). From each ovary, one mature ovum is discharged alternately with the other ovary per month. It secretes the maturation hormones for regulating menstrual cycle and embryo development.

2. The two fallopian tubes:

Each oviduct (fallopian tubes) has a funnel shaped opening. It lies just opposite the ovary to insure the fall of ovum in it; besides, it is provided with finger like processes to receive the ovum. It is lined with cilia to direct the ovum towards the uterus.

3. The uterus:

It is an elastic muscular sac-like organ. It lies in the pelvic cavity. It has a thick muscular strong wall, lined with a glandular membrane. The uterus is ended with the cervix which opens in the vagina. The embryo develops inside the uterus for 9 months.

4. The vagina:

It is a muscular tube, its length is about 7 cm that starts with the cervix and ends with the genital opening. This tube is lined with a membrane that secretes mucus fluid to moisten the vagina. Vagina has folds to allow its expansion during delivery.

N.B.:

As a female approaches maturity (at the age of 12 up to 15 years), a monthly rhythmic changes take place in the female reproductive system according to the ovarian and the uterine activities. Such activities may correlated with fertilization and pregnancy or non-pregnancy, and the monthly bleeding which is termed as menstruation.

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