HUMAN REPRODUCTION | INTRODUCTION | NEET | BIOLOGY

Human Reproduction

Human beings are sexually dimorphic organisms , i.e. , male and female are separately distinguishable . Reproductive system , whether in male or female is a collection of internal and external organs that work together to produce a new generation of living organisms similar to their parents .

The external features which provide distinctiveness to the two sexes but have no role in sexual reproduction , are collectively called secondary sex characters .

The specialised cells for reproduction or reproductive units are called gametes . Gametes are of two types : male gametes are spermatozoa and female gametes are ova . Gametes are formed in separate , paired organs of mesodermal origin , called gonads

Sperm producing gonads are called testes and ova producing gonads are called ovaries. Testes and ovaries are known as primary sex organs.

Major Reproductive Events

Gametogenesis - Formation of gametes . It includes spermatogenesis ( formation of sperms ) and oogenesis ( formation of ova or eggs ) .

Insemination - Transfer of sperm into the genital tract of female .

Fertilisation - Fusion of male and female gametes to form zygote

Cleavage - Rapid mitotic divisions of single celled zygote to develop multicellular blastocyst or blastula

Implantation - Attachment of blastocyst to the uterine wall .

Placentation - Formation of placenta between fetus and uterine wall of the mother to exchange essential materials.

Gastrulation - Development of blastocyst into gastrula with three primary germ layers.

Organogenesis - Formation of specific tissues, organs and organ - systems from three primary germ layers .

Parturition - Expelling of baby from mother's womb ( uterus ) i.e,childbirth .

MANISH MEVADA

M.Sc, M.Phil, B.Ed