Hi, welcome to this blog on the topic, reproductive system in mammals and thier various functions.
Table Of Contents
- Reproductive system in mammals
- Structure and functions of male mammalian reproductive system
- Structures and functions of female mammalian reproductive system.
- Structure mammalian gametes.
- Similarities and differences between the male and female reproductive system.
- Revision Questions.
Reproductive System In Mammals
Mammals generally are unisexual and reproduce sexually. Reproduction in mammals, e.g. man is viviparous that is, they give birth to living young ones that develops from fertilized egg. The structures and functions of the male and female reproductive system are discuss below.
Structure And Functions Of Male Mammalian Reproductive System
The male mammalian reproductive system, e.g. man consists of the following structures:
1. Testes (testis-singular): All male Mammals have two oval-shaped testes inside two sacks of skin (scrotal sacs). In man, the sacs form a scrotum which encloses the two testes. In Mammals, the testes are found outside the body cavity so as to provide a cooler environment than the body. Such environment enhances rapid production of sperm.
Functions
- The testes produce the sperms.
- They also produce the male sex hormones (testosterone) which aids the development of secondary sexual characters.
2. Seminiferous tubules: These are located within the testes. They are composed of a mass of sperm producing tubes.
Functions
- These are points where sperms are produced within the testes.
3. Epididymis: Epididymis is also found within the testes. It is a long, coiled tube.
Functions
- Epididymis collect and stores sperms temporarily until they mature.
4. Vas deferens or sperm duct: Sperm duct is a narrow tube which leads from the epididymis to the seminal vesicle.
Functions
- It carries or conducts sperm from epididymis to the seminal vesicle.
5. Seminal vesicle: The seminal vesicle is a small sac where sperms are stored. It is located close to the posterior end of the vas deferens. It secrets seminal fluid. Seminal fluid contains fructose which provided energy for the sperms.
Functions
- It stores sperms until they are ejaculated.
- It secretes part of the seminal fluid.
6. Prostrate gland: The prostate gland is connected to the urethra through many tubules. Prostate gland secretes seminal fluid which activates the sperms.
Functions
- It secretes part of the seminal fluid which activates the sperms.
7. Cowper’s gland: Cowper’s gland is located very close to the prostate gland. It also secrete seminal fluid which helps to increase the pH of the fluid in the female reproductive medium, which is normally such acidic environment can kill the sperm if it is not neutralized with the aid of cowper’s gland.
Functions
- It secretes a part of the seminal fluid which raises the pH of the female reproductive system.
8. Urethra: The urethra is a narrow tube which prolonged into the penis. In other words, the urethra passes through the penis. The urethra is Urinogenital in function, that is, it serves as a means of reproduction as well as excretion.
Functions
- It aids the passage of sperm into the vagina.
- It aids the passage of urine out of the body.
9. Penis: The penis is an intromittent organ for introducing sperms into the female reproductive organ (vagina). The penis contains spongy tissues which can be filled with blood. During sexual intercourse, the penis is stimulated especially with the aid of gland penis, by repeated pushing into vagina which eventually leads to ejaculation of sperms.
Functions
- It helps to introduce the sperm into the vagina of the female animal.
Structures And Functions Of Female Mammalian Reproductive System
In the reproductive system in mammals, the female mammalian reproductive system consists of the following structures:
1. Ovaries: There are two ovaries in a woman located on the dorsal surface of the abdominal cavity, one on each side of the vertebral column. They produced eggs. In human beings, the ovaries release one egg per month alternatively. Eggs are developed in the outermost layer of the ovary called germinal epithelium. The egg and the surrounding cells make up the mass of cells called Graphian follicle or the ovarian follicle. The cells of the graphian follicle produce a hormone called eostrogen.
The formation of the Grafian follicle is closely related to the menstrual cycle. Every month, or usually every 28 days, an egg begins to grow and the follicle begins to enlarge. Eventually, the follicle protrudes from the surface; the egg cell contained in the follicle is then released by a process called ovulation.
Functions
- Ovary produces the eggs or ova.
- It produced female sex hormones called Oestrogen and progesterone.
- It is also responsible for the development of secondary sexual characters in girls.
2. Oviduct or Fallopian tube: The oviduct or Fallopian tube is a long narrow tube with a funnel shaped opening which receives eggs (ova) released by the ovary. The oviduct links the ovary with the uterus.
Functions
- Fertilization takes place in the oviduct.
- It is the tube through which the egg or ovum passes through the ovary to the uterus.
3. Uterus or womb: The uterus is a muscular organ in whose cavity the zygote develops into a baby. If the eggs is fertilized, it becomes implanted in the wall of the Uterus. Implantation is the attachment of embryo to the wall of the uterus. The point at which the embryo is attached to the uterus developed into a placenta.
Functions
- This is the parts in which the embryo or foetus develops.
4. Virgina: The vagina is a muscular tube that leads from the uterus to the outside of the body. The penis is inserted into the vagina during mating; it therefore receives sperms. Vagina is also referred to as the birth canal because the foetus also passes out from here during birth.
Functions
- It received sperms from penis during sexual intercourse.
- Foetus also passes out of vagina during birth.
5. Cervix: The cervix is a ring of muscle with tiny aperture that closes the lower end of the uterus where it joins the vagina.
Functions
- It controls the opening and closing of the vagina especially during birth.
7. Vulva: The vulva is the collective name for all the external parts of the female reproductive organ. The vulva include the labia majora and labia minora which are pairs of folds of skin surrounding the vulva. The female reproductive system finally opens to the outside world through the vulva.
Functions
- It allows the passage of penis into the vagina.
- It permit passage of foetus during birth.
- It permits the passage of urine out of the body.
Clitoris: The clitoris is a small sensitive organ which corresponds to the penis in the male. Like the penis, it is a erectile and becomes stiff on account of flow of blood into it when stimulated.
Functions
- It helps to stimulate the female during sexual intercourse.
Structures Of Mammalian Gametes
The reproductive sex cells are also known as gametes. The formation of gametes or gametogenesis takes place in the gonads.
Male Gametes
The male sex cells or gametes called sperm are produced in the testes by a process called spermatogenesis. The gametes is unicellular in nature.
The sperm or spermatozoon consists of a head which contains the nucleus, a middle piece and a whip-like tail or flagellum. A human sperm is about 0.05mm long and microscopic and is usually smaller than the egg (ovum).
The sperm cells are produced in the testis(es) or seminiferous tubules and stored temporarily in the epididymis.
Structure And Function Of Sperm Cell
The structure of the sperm cell enables it to function effectively in fertilization in the following ways:
- Acrosome: Acrosome is located at the auterior end of the head which contains lytic enzymes or agents used to dissolve the egg membrane or it enhance penetration of the egg during fertilization.
- Middle piece: The middle piece contain numerous mitochondria which generates the energy used by the sperm cell to swim towards the egg.
- Long whip-like tail or flagellum: It is found at the posterior end of the sperm cell. It helps to move or propels the sperm cell.
- Nucleus: This is found in the head of the sperm cell and contains genetic material which fuses with the nucleus of the egg or ovum.
FEMALE GAMETES
The female sex cells or gametes called the eggs or ova are produced in the ovaries by a process called oogenesis. The human female gametes are larger than the sperms. Each ovum is about 0.1mm in diameter. It consists of the cytoplasm, a nucleus in the center, granules and yolk droplets. The yolk provides a source of nourishment for the embryo, especially at the early stages of the development.
The ovum’s cytoplasm is surrounded by two membranes. The outer one is called the vitelline membrane while the inner one is called the plasma membrane. The ovum is surrounded on the outside by a jelly coat of variable thickness made of glycoprotein. The nuclei of the sperm and ovum contain chromosomes (thread-like materials) which carry genes. The genes are responsible for transmission of characteristics from parent to offspring.
Differences Between Sperm And Egg
Sperm – Eggs
- Sperm: It is motile or active – Egg: It is not motile.
- It has smaller cytoplasm – it has larger cytoplasm.
- Food reserves/yolk is absent – food reserves/yolk presence.
- It not visible to the naked eyes – It is visible to the naked eyes.
- There is presence of head – head is not present.
- Tail or flagellum is present – tail or flagellum is absent.
- There is absence of vitelline membrane – vitelline membrane is present.
Similarities And Differences Between The Male And Female Reproductive Systems:
In the reproductive system in mammals, the male and female reproductive system are similar in the following ways:
- Both produce gametes.
- Both contains gonads (testes and ovaries).
- Both have external openings.
- Both have tubes through which the gametes pass.
- Both gonads act as ductless (endocrine) glands.
Differences
Below shows the differences between the mammalian male and female reproductive systems.
Male – Female
- Male: The gonads are located outside the body – Female: The gonads are located inside the body.
- There is presence of testes in male – Testes are absent in female.
- Ovaries are absent in male – ovaries are present in female.
- Vas deferens is present in male – vas deferens is absent in female.
- Seminal vesicle is presence In Male – seminal vesicle is absent in female.
- There is presence of penis in male – vagina is present in female.
- Male produces sperm – Female produces eggs or ova.
- There is presence of sperm duct in male – spend duct is absent in female.
- Prostate gland is present in male – prostate gland absent in female.
- There is presence of cowper’s gland in male – cowper’s gland is absent in female.
- There is no oviduct in male – there is oviduct in female.
- There is no uterus in male – uterus is present in female.
- Cervix is absent in male – cervix is present in female.
- Vulva is absent in male – vulva is present female.
- Sperm pass out through urethra in male – ova pass out through vagina if unfertilized in female.
Revision Questions
- (a) State where the sperm cell is produced and where it is stored (b) explain how the structures of the sperm cell enable it to function.
- (a) Outline five structures and functions of female mammalian reproductive system. (b) Outline five structures and functions of male mammalian reproductive system.
- In the reproductive system in mammals, Discuss the similarities and differences between the male and female reproductive system