Week 1: Fertilization
Fatimah Myers
PSY/265
March 15, 2014

University of Phoenix

Instructor – Dr. Zaleski

In fertilization, the organs that make up the reproductive system in males plays the role of producing and discharging sperm within the female reproductive tract. The penis, scrotum, testes, sperm, epididymis, and accessory organs make up the reproductive organs in a male. In addition to being used for sexual intercourse and the pathway for semen, the penis is also where urine is passed through. The scrotum is a pouch located below the base of the penis, with two compartments. The compartments of the scrotum hold the testes. Each testicle is held in place by a spermatic cord. The spermatic cord is a structure that contains the vas deferens, blood vessels and nerves, and the cremaster muscle. This muscle controls the movement of testicle within the scrotum when there is a change in temperature and sexual stimulation (Rathus & Fichner-Rathus, 2011). The testes are responsible for the production of mature germ cells and the secretion of sex hormones. The epididymis is a tube that stores sperm and lies against the back wall of each testicle. The accessory glands of the male respiratory system include the seminal vesicles, the prostate and Cowper’s gland. Seminal vesicles are 2 inches in length and located behind the bladder. The seminal vesicles open into ejaculatory ducts and secrete fluids that combine with sperm to keep it nourished and active. Sperm must be active in order to contribute to the act of fertilization. Sitting beneath the bladder is the prostate gland. This gland is shaped and sized like a chestnut and is responsible for secreting prostatic fluid. This prostatic fluid contains alkaline which neutralizes the acid-high vaginal tract and prolongs the life span of sperm as it passes through the reproductive system of the female. There are two Cowper’s glands located below the prostate. Secretions from the Cowper’s glands are emptied into the urethra, found at the top of the penis during sexual arousal, contains sperm, and precedes ejaculation. Like the male, the organs that make up the reproductive system in the female are responsible for fertilization. The mons veneris, labia majora and minora, clitoris, vestibule, vaginal opening and the perineum are the external sex organs of the female reproductive system. Internal sex organs include, the vagina, cervix, uterus, fallopian tubes, and ovaries. The mons veneris is the fatty tissue covering the joint of the pubic bones that severe as a cushion to the woman’s body and protection to the woman and man from the pressure against the pubic bone, during sexual intercourse. The labia majora are large folds of skin that hide the labia minora, urethra and vaginal openings, and the inner genitals of the female. Nerve endings within the labia majora respond to stimulation and produce sexual pleasure. The labia minora contains blood vessels, nerve endings, and are very sensitive to sexual stimulation. When stimulated, they darken and swell, engorging with blood (Rathus & Fichner-Rathus, 2011). Much like the labia majora and minora, the vestibule is sensitive to sexual stimulation. The opening to the vagina and urethra is located within the vestibule. Separating the labia minora allows one to see the vaginal opening. The perineum contains nerve endings, skin and tissue between the opening of the vagina and the anus. A woman’s vagina is a tubular sex organ that contains the penis during sexual intercourse, through which a baby is born, and is usually 3 to 5 inches long at rest (Rathus & Fichner-Rathus, 2011). Located at the lower end of the uterus is the cervix. It contributes to the chemical balancing of the vagina by producing secretions. The cervical canal allows sperm to pass from the vagina to the uterus. An ovum that has been fertilized implants and develops in the uterus until it is time for birth. Four inches in length and extending from the uterus to the ovaries are the fallopian tubes. The fallopian tubes act as a pathway to all ova to pass through to get to the uterus. They are also responsible for the nourishment and conduct of ova. Ovaries are about 1 ½ inches long and are shaped like an almond. Female sex hormones, estrogen and progesterone, and ova are produced by the ovaries. Promoting puberty and a regulated menstrual cycle happens with the production of estrogen. Like estrogen, progesterone regulates the menstrual cycle, but also prepares the uterus to accept a pregnancy. At birth, a female has about 2 million immature ova with only about 400,000 surviving into puberty (Rathus & Fichner-Rathus, 2011). During the years of reproduction, the follicles will release 1 ova per month to allow for a possible fertilization. There are steps that must occur between the sperm and an egg in order for a pregnancy to happen. The steps include, sperm transport, egg transport, fertilization and embryo development, and implantation. After ejaculation has occurred, protectant gel is formed by the sperm which acts as a protection agent from the acid-high environment of the vagina. The protected sperm travels through the cervical mucus layers. These layers act as a guard to the uterus. If the woman is ovulating the layers are thinner, which allow sperm to get through. Upon entering the uterus, the sperm travels into the fallopian tubes with the remaining sperm reserved in the cervical mucus. The transportation of the egg begins at ovulation and is over when the egg reaches the uterus. After ovulation, the fallopian tube brushes over the ovary and the egg is picked up and placed into the tube by the cilia. This transportation process takes up to 30 hours. Once ovulation is completed, the egg remains in the fallopian tube for 12 to 24 hours. During this time while the egg is located in the fallopian tube is when fertilization, the union of the sperm and the egg, occurs. After fertilization the egg rapidly travels to the uterus. The uterus is where the egg will remain while developing into a fetus. During a healthy pregnancy, development takes between 38-40 weeks at which time the fetus is prepared to live outside of the uterus.

Reference:
Rathus, S.A., Nevid, J.S, and Fichner-Rathus, L. (2011). Human sexuality in a world of diversity (8th ed.) Boston, MA: Allyn and Bacon.