Male and Female Hormones of Mammals

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Male and Female Hormones of Mammals
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Hormones are organic chemical substances which help to coordinate various functions of the bodies of animals, man and all living entities. They are produced in certain glands of the body and transported through the bloodstream to other tissues to influence their activities. 
  Hormones which coordinate reproductive functions in terms of  reproduction are called reproductive hormones. The systemic  functions of hormones are basically the same in mammals. 

Male and female reproductive hormones are as follows:


Male and female reproductive hormones
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(1)         Follicle stimulating hormone (FSH)

The follicle stimulating hormone is produced in the pituitary gland which projects from the brain. The pituitary gland is a small but very important structure which produces about twelve hormones of which one is FSH.  Some functions of the FSH are the following

(a)      Stimulating the growth and maturation of Grafian follicles on the surface if the ovary.  The Grafian follicle is the fluid –filled cavity which develops partially, surrounding an ovum in the mammalian ovary. It bursts to discharge the ovum into the fallopian funnel in the process know as ovulation.

(b)     Stimulating the growth of seminiferous tubules of the testes.  The lining of these tubules consists of continuously dividing cells which eventually produce sperms.

(c)      Production of sperms

2.    Latenising hormone (LH)

 The latenising hormone is produced in the pituitary gland of the brain.

Some functions of LH are the following:

(a)        Maturation of the Grafian follicles in the ovary.

(b)     Development  of cells in the testes. These are the reproductive organ of he mammalian male.

(c)      Influencing ovulation

3.     Oestrogen

 Oestrogen is produced in the Grafian follicles of the ovary as well as in the placenta during pregnancy.  It is a female hormone. Some of he functions of this hormone are the following: 

(a)      It stimulates the signs of heat

(b)      It is responsible for the development of the uterus and the preparation of its lining for the reception of the fertilized ovum.

(c)       It is responsible for duct development in the mammary glands.

(d)      Oestrogen is also responsible for the development of female secondary sexual characteristics includes the enlargement of the breast, enlargement for the pelvis and the appearance of hair at the armpits and pubic region.

4.    Progesteron: 

Progesteron and oestrogen are two particularly important female hormones.  Progesterone is produced in the corpus luteum which is the site of the shed ova as well as in the placenta. Its functions are as follows

(a)       It develops the uterus lining after ovulation and fertilization for implantation of the fertilized ovum or zygote.

(b)      It helps with the implantation of the fertilized ovum and the development of the placenta.

(c)       It helps to sustain pregnancy by inhibiting ovulation and preventing the wall of the  uterus from contracting

(d)       Progesterone stimulates the development of secreting cells (alveloli) in the mammary glands

The ability of progesterone to inhibit ovulation is the basis for the wide spread use of similar synthetic compounds in birth control (or contraceptive) pills 
5.     Oxytosin

Oxytosin is produced in the pituitary gland. Its functions includes the following:
(a)       It is responsible for the contraception of the uterine wall at the end of the pregnancy in order to expel the young one and the placenta during parturition.

(b)     It is responsible for the contraction of milk secreting cell (alveoli)  in the mammary glands in order to expel milk.

(c)       It is responsible for egg laying (or oviposition)poultry bird 
6.     Prolactin

  Prolactin is produced in the pituitary gland.  Its functions are the following

(a)      It stimulates the development of milk secreting cells in the mammary glands

(b)     It is responsible for the production of milk.

(c)       It is responsible for brooding behavior whereby the hen sits on the eggs during incubation and covers the young chicks with her body to provide heat and protection for them during the early weeks of their life.

7.    Thyroxin

Thyroxin is a hormone which is also produced in the pituitary glands. It undertakes the following functions

(a)      It is responsible for pigmentation

(b)     It is responsible for the structure of feathers

(c)      It is responsible for moulding in birds

 8.  Androgen or `testosterone

Testosterone is the male hormone and it is produced by the testes.  Its functions are the following:

(a)       It is responsible for the development of male secondary sexual characteristics.   Male secondary sexual characteristics in man include the emergence of hair in the armpits and pubic region, growth of beard and mustache and the breaking and deepening of the voice.

(b)      It stimulates sex drive (or libido)

(c)       It reduces puberty, which is the onset of sexual maturity.  In the female animal, sexual maturity is reached when the ovaries become functional.

To a great extent , reproductive hormones work cyclically.  Essentially, the FSH stimulates the Grafian follicles and as these grow and mature, they produce oestrogen.  Oestrogen stimulates the signs of heat in the animal and restrains the activities of FSH.  As the Grafian follicles continue to mature, L is released by the pituitary gland and this causes ovulation, which is the release of the ovum through the rapture of the follicles. 

     After ovulation, the corpus luteum (also called yellow body) develops in the ruptured` Grafian follicle and it produces progesterone and this begins to prepare the uterus for anticipated pregnancy.   If for any reason pregnancy does not occur, the corpus luteum ceases its activities  and the cycle begin again with the stimulation of the growth of another  Grafian follicle.

     However,   if mating occurs  at the appropriate time and fertiliozation results, a young one (foetus) begins to develop.  In this case, progesterone will maintain the pregnancy through term until the time of parturition.  Oxytoxin aids parturition in mammals and egg laying in poultry as well as the expelling of milk from the mammary gland. Actual milk production is stimulated by prolactin, which is also responsible for brooding behavior in poultry.  Thyroxin takes charge of pigmentation, feather structure and moulding in birds. Formation of the egg shell is influenced by parathyroid hormones.  

     Generally, in mammals, the reproductive systems as well as processes involved are similar.

 Summary

  Reproduction is one of the characteristics of living things.

1.         Mammals give birth to living young which are the replica of  their parents, have hair on their bodies and feed their young offspring with milk

2.        Birds reproduce by laying eggs which later hatch into young ones outside the bodies of their parents

3.        Mating or copulation is the coming together of sexually mature male and female animals of the same species in a sexual relationship.

4.         Fertilization is the union of the egg cell from the female animal with sperm cell from the male animal to form zygote.

5.         Heat period  is the period of time within which the female mammalian livestock is most ready to accept the male for mating

6.        Ovulation is the shedding of the egg cell called ovum from the ovary into the fallopian funnel.

7.         Gestation period is the period of pregnancy in female mammals.

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