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 1.Male Reproductive system 2.Female Reproduction 


     Reproduction is the union of the male and female Gamates to form a Zygote. As it is common with other terrestial animals, man has developed a more certain means of bringing the gamates together. 

     The sperm is produced in the numerous seminiferous tubules in the testes. From here it passed through the vasa efferentia and epididymis into the vas deferens. For the sperm to be introduced into the female, it is necessary for the penis to be inserted into the vagina in and act of coitus or corpulation. Under conditions of erotic 
excitement, the arteries in the penis dilate and the veins constrict. The resultant high blood pressure in the penis causes the penis to become erect. As the penis move up and down in the vagina, the tactile stimulation of the sensory cells at its tip triggers off a reflex. This causes the contraction of the vas deferens. Sperm is then swept down into the urethra. Here it is mixed with secretions from both the seminal vesicles and the prostate gland. These secretions keep the sperm in a viable and motile state. The admixture of the sperm and secretion is called semen. The semen is expelled from 
the penis into the vagina by a powerful contra ction of the urethra. This is called ejeculation. The reflex mechanism that brings about erection and ejaculation 
inhibits urination. 
     The sperm reaches the ovum at the upper part of the fallopian tube where fertilization takes place. Despite the fact that millions of sperm cells are produced, only few reach the ovum ; and of these few, only one sperm cell fertilizes an ovum. 

     After fertilization the zygote moves down the fallopian tube by peristalsis. It takes about one week for the zygote to reach the uterus and before then it has divided mitotically to form. Blastocyst. The embedding of the blastocyst in the uterus is called"Implantation". After implantation the blastocyst continues to develop by cell 
division. As development continues the blastocyst is called the : fetus". The fetus is enveloped by protective membrane-the 
chorion and the amnion. 


      The amnion is the inner membrane and it encloses a fluid-filled 
amniotic cavity which act as a buffer for the fetus. Later the placenta is 
formed in association with the walls of the uterus and it is connected to 
the fetus by the umbilical cord. Within the placenta, fetal and material 
blood vessels come into intimate association with each other and across 
their walls exchange of respiratory gases food materials and 
nitrogenous waste take place. 
     To accommodate the growing fetus, the uterus expands enormously 
and this is accompanied by the thickening of its walls and increased 
vascularisation. When the fetus reaches a certain age, birth or parturition 
occur. The time interval from fertilization to parturition is called the 
gestational period and it is nine months in man. 
      Actually for reproduction to occur in man, fertile sperm cells have to be 
introduced into the vagina of an ovulating woman with patent Fallopian 
tubes and an uterus. From the above, it is obvious that not all sperm cells 
can fertilize an ovum. Certain qualities are used to measure the 
potency of the sperm cells :
1. Volume :-The normal volume ranges from one millilitre to six millilitre(1-6 mls)

2. Mortility :-This should be equal to or greater than sixty percent in one 
hour or seventy percent in two hours (60% in one hour or 70% in two hours )

3. Count :-Equal to or greater than twenty million cells per millilitre of sperm produced (> 20 million cells/ml.)

4. Morphology :-Equal to or less than twenty-five percent of abnormal 
forms (< 25% abnormal forms). 

5. Pus Cell: There should be no pus cells In sperm.

Two abnormalities are associated with sperm. These are Azospermia and Azosperma


means there is no sperm cell at all in the semen. Oligospermia dents presence of sperm cell less than normal. 
Oligospermia :-Mild = 11-19 Millions/ml. 
Moderate-6-10 Millions/ml. 
Severe-Less than or equal to 5 Millions/ml.      The man as a rule must abstain from sexual intercourse for four days before Producing semen for analysis.

        READ ALSO: MENSTRUATION AND MENSTRUAL CYCLE

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