Reproductive System in Mammals

Mammals generally reproduce sexually. They are generally unisexual. Reproduction in mammals is usually viviparous - their offspring are born alive, and not eggs that need to be hatched. Reproductive system in mammals is majorly divided into two - male reproductive system and female reproductive system.


[photo credit: Zephyris]


MALE MAMMALIAN REPRODUCTIVE SYSTEM
The constituents of the male mammalian reproductive system are:

(i) Testes: Testes are two in number, oval-shaped and inside two sacs of skin called scrotal sacs. All male mammals posses testes. In man, the testes are outside the body cavity because the the outside cavity is cooler than the inner cavity and the testes need a cool environment. 

Functions of Testes
The functions of testes include:

1. production of sperm
2. production of testosterone - a sex hormone which helps in the development of secondary sexual characters

(ii) Seminiferous tubules: Seminiferous tubules are found inside the testes. They consist of many sperm-producing tubes

Function of seminiferous tubules

Seminiferous tubules are the sperm-production points in the testes

(iii) Epididymis: This is a long coiled tube. It is also located in the testes.

Function of Epididymis

Epididymis is responsible for the temporary storage of sperms before they mature

(iv) Sperm duct or Vas deferens: This is a tube which leads the epididymis to the seminal vesicle. It is narrow.

Function of Sperm duct

Sperm duct carries the sperms from epididymis to the seminal vesicle.

(v) Seminal vesicle: This is a small sac where sperms are stored. It is found in the posterior end of the sperm duct. It secretes seminal fluid, which contains fructose which provides energy for the sperm

Functions of seminal vesicle

The functions of the seminal vesicle are:

1. secretion of part of the seminal fluid
2. storage of sperm

(vi) Prostate gland: The prostate gland also secretes seminal fluid. The fluid activates sperms. Prostate gland is connected to the urethra through many tubules.

Functions of prostate gland

The prostate gland secretes part of the seminal fluid, which activates the sperms. 

(vii) Cowper's gland: This also secretes seminal fluid, which aids the increase of the pH of the female reproductive medium, which is normally acidic. And if not neutralized, the acidic environment can kill the sperm. 

Function of Cowper's gland

The Cowper's gland secretes a part of the seminal fluid, which increases the pH of the fluid in the female reproductive system.

(viii) Urethra: This is a narrow tube which passes through the penis. It is urinogenital in function - it serves as a means of excreting(urine) as well as reproduction.

Functions of urethra

The urethra aids the passage of:

1. urine out of the body.
2. sperm into the vagina. 

(ix) Penis: This is an organ used for the introduction of sperm into the vagina. It contains spongy tissues that can be filled with blood. In the event, by which it is filled with blood, the penis becomes erect. It is usually stimulated through gland penis, by the repeated push and pull into the vagina, which later results in ejaculation of sperms.

Function of the penis

The penis aids the introduction of sperm into the vagina of female animal.

FEMALE MAMMALIAN REPRODUCTIVE SYSTEM

The constituents of the female mammalian reproductive system are:

(i) Ovaries: Ovaries are two in number. They are found in the dorsal surface of the abdomen. One is found on each side of the vertebral column. They are responsible for the production of egg. In human beings, they release one egg per month alternatively. 

Functions of the ovaries

The functions of the ovaries are:

1. production of eggs.
2. production of estrogen(oestrogen) and progesterone. 
3. development of secondary sexual characters.

(ii) Oviduct or Fallopian tube: The oviduct receives eggs release by the ovaries. It is a long narrow tube with a funnel-shaped opening. It links the ovary with the uterus(womb).

Functions of the oviduct

1. It serves as the tube through which eggs pass from the ovary to the uterus(womb).
2. Fertilization takes place in the oviduct.

(iii) Womb or Uterus: This is a muscular organ, where the zygote develops into a baby. After fertilization, the egg becomes implanted in the walls of the womb.

Functions of the Uterus

It serves as the part, inside whose cavity the embryo develops.

(iv) Vagina: This is a muscular tube, which leads the uterus to the outside of the body. It receives sperms from the penis. The vagina is also known as the birth canal, because the fetus(foetus) passes out from here during birth.

Functions of the vagina

1. The vagina receives sperms from penis during sex
2. It serves as the birth canal - Fetus(foetus) passes out of it during birth.

(v) Cervix: This is a ring of muscle with tin aperture that closes the lower end of the uterus where it joins the vagina.

Function of the cervix

The opening and closing of the vagina during birth is controlled by the cervix.

(vi) Vulva: This is the collective name for all the external parts of the female reproductive organ. It includes labia majora and labia minora. 

Functions of the vulva

The vulva permits the passage of:

1. fetus(foetus) during birth.
2. penis into the vagina
3. urine out of the body

(vii) Clitoris: This is a small organ, which functions like the penis in the male. It is sensitive. Just like penis does, it can become erect when blood flows into it when stimulated.

Functions of the clitoris

Clitoris aid in the stimulation of females before and during sex.

Differences Between Sperm and Egg

Sperm	Egg
Head is present	Head is absent
Flagellum is present	Flagellum is absent
It has smaller cytoplasm	It has larger cytoplasm
Vitelline membrane is absent	Vitelline membrane is present
It is motile	It is not motile

Recommended:

Reproductive System in Flowering plants

Reproductive System in Reptiles, Fish, Birds

Categories: Biology, Reproduction, Reproductive System