REPRODUCTION IN HUMAN BEING

        IN THIS CHAPTER WE READ ABOUT THE MOST INTRESTED SPECIES,NAMELY HUMAN.  HUMAN BEING ARE USE A SEXUAL MODE OF REPRODUCTION .AND WE KNOW THAT AS WE BECOME OLDER OUR BODIES CHANGE.OUR HEIGHT OR OUR WEIGHT AND WE ACQUIRE TEETH WE EVEN LOSS OLD SO CALLED MILK TEETH AND ACQUIRE NEW ONES.ALL OF THESE ARE VARIATION THAT CAN BE GROUPED UNDER THE NORMAL PROCESS OF GROWTH,IN WHICH THE BODY BECOMES LARGER. BUT IN EARLY TEENAGE YEARS ,A WHOLE NEW SET OF CHANGES TAKES PLACE THAT CAN NOT BE DISCRIBED SIMPLY AS BODY  ENLARGEMENT INSTEAD THE BODY APPEARENCE CHANGES .NEW FUTURES APPEAR PROPORTION CHANGE AND DO NEW SENSATION.

      ON OTHER VIEW THERE ARE ALSO CHANGES OCCURING THAT ARE DIFFERENT BETWEEN GIRLS AND BOYS .IN GIRLS ,BREAST SIZE START TO INCREASE,WITH DARKENING OF THE SKIN OF THE NIPPLES AT THE TIPS OF BREASTS. ALSO GIRLS START TO MENSTRUATE AT AROUND THIS TIME.BOYS START TO HAVE NEW THICK HAIR GROWTH ON THE FACEAND THEIR VOICE START TO CRACK. AND THE PENIS OCCASIONALY START TO BECOME ENLARGED AND ERECT EITHER AT NIGHT OR IN DAYDREAMALL OF THESE CHANGES OCCUR SLOWLY OVER A PERIOD OF MONTH AND YEARS.

            HOWEVER ,WHILE THE BODY OF INDIVIDUALORG ARE TO ITS ADULT SIZE.THE RESOURCE OF THE BODY ARE MAINLY DIRECTED FOR GETTING THIS GROWTH.WHILE THAT IS OCCURING THE MATURATION OF THE REPRODUCTIVE TISSUE STARTS TO MATURE,THIS PERIOD DURING ADOLESCENCE IS KNOWN AS PUBERTY.

  THE MALE REPRODUCTIVE SYSTEM-

                         IS CONSIST OF PORTION WHICH PRODUCE THE GERM CELL AND OTHER PORTION THAT TRANSFERRED .THE GERM CELL TO THE SITE OF FERTILISATION .THE FORMATION OF GERM CELLS OR SPERMS OCCUR IN THE TESTES .THESE ARE PRESENT OUTSIDE THE ABDOMINAL CAVITY IN SCORTUM BECAUSE SPERM PRODUCTION REQUIRE A LOWER TEMP THAN THE NORMAL BODY TEMP. IN ADDITION TO REGULATING THE PRODUCTION OF SPERMS ,TESTOSTERONE BRINGS ABOUT CHANGES IN APPEARENCE OF OBSERVED IN BOYS AT THE TIME OF PUBERTY. THE SPERM PRODUCED ARE DELIVERED THROUGH THE VAS DEFRENSE WHICH JOINS A TUBE COMING FROM THE URINARY BLADDER .THE URETHRA THUS FORMS A COMMAN PASSAGE FOR BOTH THE URINE AND SPERMS .THE SPERMS ARE TINY BODIES CONTAINING MAINLY GENETIC MATERIAL AND A LONG TAIL THAT SPORTS IT TO MOVE TOWARDS THE FEMALE GERM CELL.

 THE FEMALE REPRODUCTIVE SYSTEM -

                              THE EGGS OR FEMALE GERMS CELL ARE MADE IN THE OVARIES .THEY ARE ALSO RESPONSIBLE FOR THE GENERATION OF SOME HORMONES .WHEN A GIRL BABY IS BORN,THE OVARIES ALREADY HAVE THOUSAND OF IMMATURE EGG IN THEM .ON REACHING PUBERTY SOME OF THESE BEGIN TO MATURE. ONE EGG IS FORMED EVERY MONTH BY ONE OF THE OVARIES. THE EGG IS CARRIED FROM THE OVARIES TO THE WOMB ACROSS A THIN OVIDUCT OR FALLOPIAN TUBE .THE TWO OVIDUCTS UNITE INTO ELASTIC BACK LIKE STRUCTURE CALLED UTERUS.THE UTERUS OPEN INTO THE VAGINA BY THE CERVIX .THE SPERMS ENTER THROUGH THE VAGINAL PASSAGE DURING SEXUAL INTERCOURSE .THEY MOVE UPWARDS THE OVIDUCTS .WHERE THEY MAY ENCOUNTER THE EGG THE FERTILISED EGG KNOWN AS ZYGOTE. GETS IMPLANTED IN THE LINING OF THE UTERUS AND START DIVIDING.

                                              HENCE THE THE UTERUS PREPARE ITSELF EVERY MONTH TO RECEIVE AND NURTURE THE GROWING CHILD .THE LINING THICKENS AND IS RICHLY SUPPLIED WITH BLOOD VESSELS TO NOURISH THE GROWING EMBRYO.