human reproduction

Human reproduction is sexual and humans are viviparous

Gametogensis-->insemination -->fertilisation-->implantation-->gestation-->parturition

the process of formation of gametes i.e. sperms in males and ovum in female

Transfer of sperms into the female genital tract

fusion of male and female haploid gametes leading to formation of diploid zygote

zygote formed develops as blastocyst(32-celled) implantation is the process of attachment of blastocyst to the uterine wall

the process or period of embryonic development

delivery of baby

in males,sperm formation begins during puberty and continues throughout life in females oogenesis begins during embryonic stage formation of ovum and its release stops around at the age of 50

located in the pelvis region ,male reproductive system includes a pair of testes male accessory ducts male accessory glands and male external genitalia

testis is oval shaped in adults length - 4 to 5 cm width - 2 to 3 cm the testis is covered by a dense covering (tunica albugenia)

the testes are positioned outside the abdominal cavity within a pouch called scrotum the scrotum maintains the testes at a temperature of 2-2.5°C lower than the normal internal body temperature which is necessary for spermatogenesis

Each testis has about 250 compartments called testicular lobules Each lobules contains one to three highly coiled seminiferous tubules Seminiferous tubules are the structural and functional units of testis Spermatogenesis occur in the walls of seminiferous tubules

Each Seminiferous tubule is lined on its inside by the germinal epithelium consisting of two types of cells male germ cells(spermatogonia) sertoli cells

these are male germ cells which undergo meiotic divisions finally leading to sperm formation

cells which provide nutrition to the germ cells sertoli cells also secrete certain factors which help in Spermiogenesis(conversion of spermatid to spermatozoa)

these are the regions of testicular lobules seen outside the seminiferous tubules ,stroma is richly vascularised with numerous small blood vessels

these are patches of endocrine cells in the stroma which synthesise and secrete testicular hormones called androgens stroma also contains immunological competent cells

the male sex accessory ducts include rete testis, vesa efferentia, Epididymis,vas deferens male accessory ducts store and transport sperms

the seminiferous tubules of testis open into the rete testis, Rete testis is an interconnected network of delicate tiny tubules located within the central connective area of testis. It receives the sperms and fluid from the seminiferous tubules and channels then towards the vasa efferentia

fine tubules that comes out from testis and open into the epididymis which is located outside the testis at its posterior side vasa efferentia transport sperms from rete testis to epididymis

an elongated (4-6m) and highly coiled duct located along the posterior surface of each testis epididymis stores sperms upto ejaculation Sperms acquire physiological maturation and ability for motility within the epididymis

epididymis leads to vas deferens which is a straight duct it ascends into the abdomen loops over the urinary bladder and reaches below the bladder at this point below the urinary bladder a duct from seminal vesicle joins the vas deferens and the common duct is called ejaculatory duct

A common duct formed by the convergence of vas deferens and the duct from seminal vesicle Ejaculatory duct transports sperms and the secretion from seminal vesicle into the urethra by passing through prostate gland

the duct from urinary bladder urethra in males is the urinogenital duct that transports urine and sperms urethra originates from urinary bladder and extends through penis to its external opening called urethral meatus

seminiferous tubules --> Rete testis --> vasa efferentia --> Epididymis --> vas deferens --> Ejaculatory duct --> urethra --> urethral meatus

seminiferous vesicle (a pair) prostate gland (unpaired) bulbourethral gland (cowper's glands)

secretion of male accessory glands constitute the seminal plasma which is rich in fructose, calcium, certain enzyme,secretion of bulbourethral glands also help in the lubrication of penis

seminal vesicle secretes a viscous alkaline fluid which form around 70% of seminal plasma it is a fructose rich secretion Which provide nourishment and energy to spermatozoa prostaglandins present in the secretion of seminal vesicle initiates muscular contractions in female reproductive tract which help in the transport of sperms

secretion released by the prostate gland form around 20-25% of total seminal plasma it contains citric acid, cholesterol,phospholipids,zinc calcium, acid phosphatase, prostate specific antigens etc

it is made up of special spongy tissue and blood vessels that helps in the erection of penis to facilitate insemination. the enlarged end of penis called the glans penis is covered by a loose fold of skin called foreskin(prepuce)