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Human reproduction

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Humans show sexual dimorphism i.e males and females look different morphologically. They are viviparous i.e give birth to young ones. The males produce sperms and the females produce ova. The fertilization is internal. In humans the reproductive events start at puberty.

The major reproductive events in human beings are as follows:
  • Gametogenesis : It is the process of formation of haploid gametes i.e. sperm in males and egg or ovum in females.
  • Insemination : It is the process of introducing sperms into the reproductive tract of female.
  • Fertilization : It is the fusion of two types of gametes i.e. egg and sperm inside the female reproductive tract. It is also known as syngamy.
  • Clevage : As a result of fertilization a single diploid cell is formed, it is called called zygote. The zygote undergoes repeated mitotic division called cleavage.
  • Implantation : It is the process of fixation of blastula in the uterine wall at an appropriate site.
  • Placentation : In order to supply nutrients and for exchange of toxic substances a temporary structure is formed between the foetus and the mother. This temporary structure is called Placenta. The process of formation of placenta is called placentation.
  • Gastrulation : The process of formation of gastrula is called gastrulation. As a result 3-germ layers are formed. These are ectoderm, endoderm and mesoderm.
  • Organogenesis : The process of formation of organs of foetus from germ layers is known as organogenesis.
  • Parturition : When the foetus is fully formed, its expulsion from mother's womb is called parturition.
These functions are carried out by the primary and accessory reproductive organs. The primary reproductive organs namely the ovary and testis are responsible for producing the ova and sperms respectively. Hormones secreted by the pituitary gland and the gonads help in the development of the secondary sexual characteristics, maturation of the reproductive system and regulation of normal functioning of the reproductive system. The accessory organs help in transport and to sustain the gametes and to nurture the developing offspring.





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