CBSE Class 12 Biology
Revision Notes
CHAPTER-03
HUMAN REPRODUCTION
Humans are sexually reproducing and viviparous. The reproductive events in humans
include formation of gametes (gametogenesis), i.e., sperms in males and ovum in
females, transfer of sperms into the female genital tract (insemination) and fusion of
male and female gametes (fertilisation) leading to formation of zygote. This is followed
by formation and development of blastocyst and its attachment to the uterine wall
(implantation), embryonic development (gestation) and delivery of the baby (parturition).
The Male Reproductive System: It consists of:
a) Primary sex organs i.e. a pair of testes suspended in a scrotum.
b) Secondary sex organs i.e. a pair of ducts each differentiated into rete testis, vasa
efferentia, epididymis and vas deferens ,ejaculatory duct and the associated glands
c) External genitalia
•The testes are situated outside the abdominal cavity in a pouch called scrotum, which
help in maintaining the low temperature of testes necessary for spermatogenesis.
•Each testes has about 250 testicular lobules and each lobule contain highly coiled
seminiferous tubules in which sperms are produced. Each seminiferous tubules is
lined by two types of cells, spermatogonia ( male germ cell) and Sertoli cells.
•Leydig cells or interstitial cells present around the seminiferous tubules synthesize
and secrete androgen hormone.
Fig.: 3.1 Male Reproductive System
, •Ejaculatory duct store and transport the sperm from testes to outside through urethra
which originate from urinary bladder and extend through penis to its externalopening
urethral meatus.
•The penis is male external genitalia. The enlarged end of penis is called the glans penis
is covered by a loose fold of skin called foreskin.
•Male accessary glands include paired seminal vesicles, prostrate and paired
bulbourethral glands. Secretion of these glands forms the seminal plasma which
contains fructose, calcium and enzymes. The secretion of bulbourethral glands also
helps in lubrication of the penis.
The Female Reproductive System: It consists of :
a)The primary sex organ that is a pair of ovaries
b)Secondary sex organs- the duct system consisting of a pair of fallopian tube , a uterus ,
cervix and vagina
c)External genitalia
d)Mammary glands
•Ovaries are primary female sex organ that produce the female gamete and several
steroid hormones. Each ovary is covered by thin epithelium which encloses the
ovarian stroma, which is divided into a peripheral cortex and an inner medulla.
•Fallopian tube extends from periphery of ovary to the uterus. The part closer to ovary
is a funnel shaped structure called infundibulum having finger like projection called
fimbriae.
•Infundibulum leads to ampulla and join with uterus with isthmus. Uterus is pear
shaped structure also called womb.
•Uterus open vagina through a narrow cervix. The cavity of cervix (cervical canal)
along with vagina forms the birth canal.
•The wall of uterus has three layers of tissue:
I. Perimetrium- external membrane.
II. Myometrium – middle thick layer of smooth muscles which exhibit strong contraction
during delivery of baby.
Revision Notes
CHAPTER-03
HUMAN REPRODUCTION
Humans are sexually reproducing and viviparous. The reproductive events in humans
include formation of gametes (gametogenesis), i.e., sperms in males and ovum in
females, transfer of sperms into the female genital tract (insemination) and fusion of
male and female gametes (fertilisation) leading to formation of zygote. This is followed
by formation and development of blastocyst and its attachment to the uterine wall
(implantation), embryonic development (gestation) and delivery of the baby (parturition).
The Male Reproductive System: It consists of:
a) Primary sex organs i.e. a pair of testes suspended in a scrotum.
b) Secondary sex organs i.e. a pair of ducts each differentiated into rete testis, vasa
efferentia, epididymis and vas deferens ,ejaculatory duct and the associated glands
c) External genitalia
•The testes are situated outside the abdominal cavity in a pouch called scrotum, which
help in maintaining the low temperature of testes necessary for spermatogenesis.
•Each testes has about 250 testicular lobules and each lobule contain highly coiled
seminiferous tubules in which sperms are produced. Each seminiferous tubules is
lined by two types of cells, spermatogonia ( male germ cell) and Sertoli cells.
•Leydig cells or interstitial cells present around the seminiferous tubules synthesize
and secrete androgen hormone.
Fig.: 3.1 Male Reproductive System
, •Ejaculatory duct store and transport the sperm from testes to outside through urethra
which originate from urinary bladder and extend through penis to its externalopening
urethral meatus.
•The penis is male external genitalia. The enlarged end of penis is called the glans penis
is covered by a loose fold of skin called foreskin.
•Male accessary glands include paired seminal vesicles, prostrate and paired
bulbourethral glands. Secretion of these glands forms the seminal plasma which
contains fructose, calcium and enzymes. The secretion of bulbourethral glands also
helps in lubrication of the penis.
The Female Reproductive System: It consists of :
a)The primary sex organ that is a pair of ovaries
b)Secondary sex organs- the duct system consisting of a pair of fallopian tube , a uterus ,
cervix and vagina
c)External genitalia
d)Mammary glands
•Ovaries are primary female sex organ that produce the female gamete and several
steroid hormones. Each ovary is covered by thin epithelium which encloses the
ovarian stroma, which is divided into a peripheral cortex and an inner medulla.
•Fallopian tube extends from periphery of ovary to the uterus. The part closer to ovary
is a funnel shaped structure called infundibulum having finger like projection called
fimbriae.
•Infundibulum leads to ampulla and join with uterus with isthmus. Uterus is pear
shaped structure also called womb.
•Uterus open vagina through a narrow cervix. The cavity of cervix (cervical canal)
along with vagina forms the birth canal.
•The wall of uterus has three layers of tissue:
I. Perimetrium- external membrane.
II. Myometrium – middle thick layer of smooth muscles which exhibit strong contraction
during delivery of baby.
