The Reproductive System

Male Reproductive System

The human male reproductive system (or male genital system) consists of a number of sex organs that are a part of the human reproductive process. The main male sex organs are the penis and the testes which produce semen and sperm, which as part of sexual intercourse fertilize an ovum in female's body and the fertilized ovum (zygote) gradually develops into a fetus, which is later born as a child.

External genital organs Internal genital organs Penis The penis is the male copulatory organ. It has a long shaft and enlarged bulbous-shaped tip called the glans penis, which supports the foreskin. 2. Scrotum The scrotum is a pouch-like structure that hangs behind the penis. It holds and protects the testes. It also contains numerous nerves and blood vessels. Internal genital organs Epididymis The epididymis is a whitish mass of tightly coiled tubes cupped against the testicles. It acts as a maturation and storage place for sperm before they pass into the vas deferens, tubes that carry sperm to the ampullary gland and prostatic ducts.

3. Vas deferens 4. Accessory glands The vas deferens, also known as the sperm duct, is a thin tube approximately 43.2 centimeters long that starts from the epididymis to the pelvic cavity. 4. Accessory glands Three accessory glands provide fluids that lubricate the duct system and nourish the sperm cells. They are the seminal vesicles, the prostate gland, and the bulbourethral glands (Cowper glands). I. Seminal vesicles Seminal vesicles are sac-like structures attached to the vas deferens at one side of the bladder. They produce a sticky, yellowish fluid that contains fructose. This fluid provides sperm cells energy and aids in their motility. 70% of the semen is its secretion. II. Prostate gland The prostate gland surrounds the ejaculatory ducts at the base of the urethra. The prostate gland is responsible for the production of semen, a liquid mixture of sperm cells, prostate fluid and seminal fluid.

III. Bulbourethral glands The bulbourethral glands, also called Cowper glands غدة كوبر, are two small glands located on the sides of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. It produces substances related to nourishment of spermatozoa تغذية الحيوانات المنوية .

Male Reproductive System 5. Testes It is the male gonad in animals. The primary functions of the testes are to produce sperm (spermatogenesis) and to produce androgens, primarily testosterone. It contains very fine coiled tubes called seminiferous tubules الأنيببات المنوية . The tubules are lined with a layer of cells (germ cells) that from puberty into old age, develop into sperm cells (also known as spermatozoa or male gametes).

Male Reproductive System (cont.) Spermatogenesis Spermatogenesis Spermatogonia (46 chromosomes) Mitosis – makes primary spermatocytes Undergo meiosis  two secondary spermatocytes Divides – two spermatids = 4 spermatids Develop flagella to become mature sperm cells with 23 chromosomes

SPERMATOGENESIS

Male Reproductive System (cont.) Sperm cells Head Nucleus with 23 chromosomes Acrosome – enzyme-filled sac Helps sperm penetrate ovum Midpiece القطعة الوسطي Mitochrondria that generate cell’s energy Tail Flagellum that propels sperm forward

Female Reproductive System: The human female reproductive system (or female genital system) contains two main parts: the uterus, which hosts the developing fetus, produces vaginal and uterine secretions, and passes the male's sperm through to the fallopian tubes; and the ovaries, which produce the female's egg cells. The female internal reproductive organs are the vagina, uterus, fallopian tubes, cervix and ovary.

Female Reproductive System: Vagina The vagina is the place where semen from the male is deposited into the female's body at the climax of sexual intercourse. Cervix The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. Uterus The uterus or womb is the major female reproductive organ of humans. The uterus provides mechanical protection, nutritional support, and waste removal for the developing embryo (weeks 1 to 8) and fetus (from week 9 until the delivery). In addition, contractions in the muscular wall of the uterus are important in pushing out the fetus at the time of birth.

Female Reproductive System: Oviducts The Fallopian tubes or oviducts are two tubes leading from the ovaries of female mammals into the uterus. On maturity of an ovum, the follicle and the ovary's wall rupture, allowing the ovum to escape and enter the Fallopian tube. Ovaries The ovaries are small, paired organs that are located near the lateral walls of the pelvic cavity. These organs are responsible for the production of the ova and the secretion of hormones.

Internal Female Organs Female Reproductive System Internal Female Organs uterus uterine tube ovary cervix vagina

Oogenesis Generation of eggs Starts in fetal period No more oocytes made after about 7th month Developed only to early stage of meiosis I by birth and stops (called primary oocyte) 6-12 primordial oocytes each cycle selected to develop for ovulation (most die) Only then is meiosis I completed Secondary oocyte is then arrested in meiosis II Meiosis II not completed (now an ovum) unless sperm penetrates its plasma membrane Of the 4 daughter cells, only one becomes ovum (needs a lot of cytoplasm) The other 3 become “polar bodies”