Accessory Organs

Accessory and primary organs make up a system. In biological systems, different levels of organization can be seen that makes an organism simple to complex. Initially, similar types of cells come together to form tissues. Tissues join to form organs. Different organs contributing to similar function make up a system.

For example, in our digestive system, different organs are present which function to contribute to digestion and absorption of food matters. The main organs of digestive system include oesophagus (food pipe), stomach, intestines, etc. which help the food to move through the digestive tract. Liver, pancreas, etc. are also the organs of the digestive system that secrete different enzymes that breaks the food into smaller particles helping in smooth movement and absorption of food in the body. These organs do not take part in the movement of food through the digestive tract, but help in the process. These organs are the accessory organs of the digestive system.

Key words: Primary organs, accessory organs, digestive system, reproductive system, accessory sex organs, gonads.

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What are accessory organs?

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Biological systems are made up of organs that contribute to similar function. The organs that contribute to the main function of the system are called main organs of the system. Example- stomach, oesophagus, etc. are the main organs of digestive system that function in the movement of food through the digestive tract.

Besides these organs, there are organs in the system which does not contribute to the main function but help the main organs to function properly are called accessory organs. Example- Digestive glands such as liver, gall bladder, pancreas, etc. function in the breakdown of food matters into smaller particles thereby contributing in the smooth functioning of the system.

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Accessory organs of the reproductive system

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What is reproductive system?

The group of organs concerned with the reproductive functions of a living organism are collectively called reproductive system.

In case of humans, males and females have distinctly different sexual reproductive systems. Both of these are composed of both primary and secondary or accessory sex organs.

• Primary sex organs

Primary sex organs are those which function in production of gametes. These are also called gonads. In males, primary sex organ is testis (plural- testes) which produces sperms and in females, ovaries function as gonads to produce ovum. Primary sex organs secrete different hormones for the production and maintenance of gametes.

• Accessory sex organs

Secondary or accessory sex organs are those which do not produce gametes or hormones but are otherwise required for sexual reproduction.

In males, accessory sex organs include epididymis, vas deferens, prostate gland, seminal vesicles, etc. and in females, accessory sex organs are uterus, fallopian tube, vagina, etc.

Accessory sex organs are mainly concerned with the storage, nourishment, transport and fertilization of gametes and development of zygote.

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Accessory organs of the male reproductive system

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The detailed description of accessory organs of male reproductive system are as follows—

1. Vasa efferentia

It is a bunch of fine tubular structure which is connected to the caput epididymis. It has large columnar ciliated and small non-ciliated cells with endocytic cavity.

Ciliated cells of vasa efferentia help in conducting sperms.

2. Epididymis

Epididymis are two long, highly coiled, narrow tubules. Each epididymis is differentiated into upper caput epididymis, middle corpus epididymis and lower cauda epididymis.

Epididymis is responsible for nourishment and maturation of spermatozoa. Sperms gain motility in epididymis. Here, sperms are stored for few hours to few days until ejaculation. Sperms that are not ejaculated are reabsorbed.

Male reproductive system

3. Vas deferens

These are a pair of thick walled muscular tubes that arise from cauda epididymis. 

Vas deferens conveys sperms during sexual act from epididymis towards the urethra by peristaltic movement.

4. Penis

Penis is male erectile copulatory organ which also passes out urine. Penis has a long expanded tip called glans penis which is covered by a foreskin called prepuce. Surgical removal of prepuce is called circumcision.

Penis acts in ejaculation of semen from urethra to the exterior during sexual intercourse.

5. Seminal Vesicles

It is a pair of lobulated musculoglandular sacs that are present between urinary bladder and rectum. Each seminal vesicle has a tube that joins the vas deferens is known as ejaculatory duct.

Secretion of seminal vesicle forms a major part of semen. The secretion contains fructose, prostaglandin and clotting proteins (different from those of blood).

6. Prostate gland

Large reddish to greyish pyramidal gland that encloses a part of urethra.

Prostate gland secretions are slightly alkaline and contains calcium, phosphate, proteolytic enzymes, etc. This alkalinity is useful in neutralization of acidity of vagina.

7. Prostatectomy- Surgical removal of prostate gland. Causes sterility.

8. Cowper’s gland or bulbo-urethral gland

It is a pair of small pea-sized glands located below the prostate gland.

Secretion of Cowper’s gland is alkaline and rich in mucous. It lubricates female genital tract.

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Accessory organs of the female reproductive system

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The detailed description of accessory organs of female reproductive system are as follows—

1. Fallopian tubes

It is a pair of muscular internally ciliated tubes that arises at the ovary and ends at uterus. The fimbrial end of Fallopian tube receives secondary oocyte from the ruptured follicle during ovulation. The ampulla part of Fallopian tube acts as a site of fertilization of ovum by sperms.

2. Uterus

Uterus is a muscular thick-walled inverted pear shaped organ located above and behind the urinary bladder. Lining of uterus has three layers— the inner endometrium, middle myometrium and the outer perimetrium. During bleeding phase of menstrual cycle, the blood vessels of endometrium gets ruptured.

Endometrium acts as a site for implantation of zygote in the blastocyst stage. Development of the foetus also takes place here. Uterine muscles contract to help in the parturition of foetus.

Female reproductive system

3. Vagina

It is the tubular copulatory organ of female. Vagina acts as a receptacle of male copulatory organ, penis, during sexual intercourse and also acts as a passage for menstrual flow and child birth.

4. Bartholin gland

It is a pair of small glands that open laterally to the vaginal orifice. Secretion of Bartholin gland is meant for lubrication and neutralizing acidic environment arisen due to urine.

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Points to remember

• Systems are made up of organs that have similar function.
• Primary or main organs of a system are those which perform the specific function related to that system.
• Accessory organs are the ones that help the primary organs in performing the specific function.
• Primary organs of the human reproductive system or the primary sex organs of males are a pair of testes and in females, a pair of ovaries.
• Primary sex organs produce gametes— sperms in males and ovum in females.
• Secondary sex organs or accessory organs of the reproductive system help in the nourishment and maturation of gametes.
• Fructose is not produced in human but is present in seminal fluid. Presence of fructose in female genitalia confirms sexual intercourse and often used to prove rape cases.
• Bartholin gland of females are homologous to male Bulbourethral (Cowper’s) gland.