Primary and Secondary Sex Organs: Description, Characteristics

What are Primary Sex Organs?

The primary sex organs, or gonads, are associated with the production of gametes and sex hormones. The testes are the male primary sex organs, and the ovaries are the female primary sex organs.

Role of Primary Sex Organs

Primary sex organs (testes in males and ovaries in females) are responsible for producing gametes—sperm and ova—and secreting sex hormones like testosterone and estrogen.

Male Primary Sex Organs

Testes: The testes produce sperm and the hormone testosterone. They are located outside of the abdomen within the scrotum, which provides the proper temperature for spermatogenesis.

Female Primary Sex Organs

Ovaries: Ovaries are the organs wherein the eggs (ovum) and the female sex hormones, namely estrogen and progesterone, are produced. The process of formation of an ovum is known as oogenesis. They are paired organs, meaning that there are two, and are located in the pelvic cavity on each side of the uterus.

What are Secondary Sex Organs?

The secondary sex organs give rise to secondary sex characteristics and support sexual intercourse. They support the primary sex organs in performing their role.

Role of Secondary Sex Organs

Secondary sex organs (like the penis, vas deferens, uterus, and vagina) support the transport, fertilization, and nurturing of gametes and embryos, facilitating successful reproduction.

Epididymis

This is a coiled tube at the back of each testis responsible for storing and maturing sperm. It also connects the sperm from the testes to the vas deferens.

Vas Deferens:

This is a muscular tube that carries mature sperm from the epididymis to the urethra. Aside from this, it also carries along with it the seminal fluid coming from the seminal vesicles.

Seminal Vesicles

The seminal vesicles are sac-like glands which produce a fructose-rich nutrient fluid, a type of food for the sperm to gain motility.

Prostate Gland

The prostate gland secretes fluids that nourish and protect the sperm. The fluids form part of the semen. All the male accessory ducts and male accessory glands work in harmony to support sperm transport and fertilisation.

Urethra

The urethra is a tube through which the urinary bladder discharges urine, and the male reproductive system discharges semen to the outside of the body via the penis.

Penis

The penis is the male external reproductive organ that conveys the sperm into the female reproductive tract during intercourse. It has erectile tissue, allowing it to engorge with blood, and therefore be erected.

Secondary Sex Organs Of The Female

Fallopian Tubes

The fallopian tubes take the egg from the ovary into the uterus. Fertilisation usually occurs within the fallopian tube.

Uterus

The uterus is a muscular organ in which a fertilised egg implants and grows into a fetus. Its lining is called the endometrium, and it thickens up anticipating pregnancy. The fallopian tube and the uterus are the sites of fertilisation in humans and implantation of the ovum, with the development of the fertilised egg, respectively.

Cervix

The cervix is located at the lower end of the uterus and it opens into the vagina. This part of the uterus acts as a one-way passage because, despite allowing sperm to pass into the uterus, it does not allow menstrual blood to come out of it.

Vagina

The vagina is a muscular tube connecting the cervix to the external genitalia. It acts as a birth canal, and it is also the receptacle for the penis during sexual intercourse.

External Genitalia

The female external genitalia, or vulva, include the clitoris, labiae, and opening of the vagina. While they trigger sexual arousal, they also protect the internal organs.

MCQs on Primary and Secondary Sex Organs

Q1. Which of the following is a secondary sex organs in male?

Option 1: Rete testes

Option 2: Seminiferous tubules

Option 3: Seminal vesicles

Option 4: Both a & c

Correct answer: (4) both a & c

Explanation:

Secondary sex organs in males consist of accessory ducts and accessory glands.

The male sex accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens. rete testes and epididymis are secondary/ accessory sex organs. The male accessory glands include paired seminal vesicles, prostate and paired bulbourethral glands. Seminiferous tubules are functional units of testes that merge into a network of tiny tubules called rete testes. Rete testes are secondary sex organs in males. Seminal vesicles are accessory glands that are secondary sex organs in males. Seminiferous tubules are functional units of testes that we primary sex organs in males.

Hence, the correct option is (4) both a & c

Q2. Among the given pairs of homologous structures, which one is mismatched?

Option 1: Clitoris and penis

Option 2: Vagina and prostatic utricle

Option 3: Scrotum and labia majora

Option 4: Fallopian tube and prostate gland

Correct answer: 4) Fallopian tube and prostate gland

Explanation:

The fallopian tube and prostate gland are not homologous structures because they serve different functions in the reproductive systems of males and females. The fallopian tube is part of the female reproductive system involved in transporting eggs from the ovary to the uterus. On the other hand, the prostate gland is found in males and plays a role in producing and secreting seminal fluid. While both structures are involved in reproduction, they have distinct origins and functions, making them mismatched as homologous structures.

Hence, the correct answer is option 4) Fallopian tube and prostate gland

Q3. Which of the following are accessory glands of the male reproductive system?

Option 1: Bulbourethral glands

Option 2: Prostate gland

Option 3: Seminal vesicles

Option 4: All of the above

Correct answer: 4) All of the above

Explanation:

• Secondary sex organs in males consist of accessory ducts and accessory glands.

• The male sex accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens. rete testes and epididymis are secondary/ accessory sex organs.

• The male accessory glands include paired seminal vesicles, prostate and paired bulbourethral glands.

Hence, the correct answer is Option 4) All of the above

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