This document provides an overview of the human reproductive system. It describes the main structures and functions of both the male and female reproductive systems. In the male system, it outlines the penis, testicles, and epididymis. In the female system, it details the vagina, cervix, uterus, oviducts, and ovaries. It also discusses secondary sex characteristics in males and females. Other sections explain gametogenesis, spermatogenesis and oogenesis, the menstrual cycle, fertilization, implantation and development, and gestation.

1. The Human Reproductive
System
Grade 12
T. SIBEKO

2. • Table of Contents
• The structure of the male reproductive systems
• The structure of the female reproductive systems
• Male secondary sex characteristics
• Female secondary sex characteristics
• Gametogenesis
• Menstrual Cycle
• Gestation
• Implantation and Development

3. Male Reproductive System
• The human male reproductive
system consists of a number of sex
organs that are a part of the human
reproductive process. In the case of
men, these sex organs are located
outside a man's body, around the
pelvic region.

4. Male Reproductive System
1. Penis
2. Testicles( Scrotum)
3. Epididymis

6. Male Reproductive System
Penis
• The penis has a long
shaft and enlarged tip
called the glans penis.
• The penis is the male
copulatory organ.
• When the male
becomes sexually
aroused, the penis
becomes erect and
ready for sexual
intercourse.
• .

7. Male Reproductive System
• Erection is achieved because blood sinuses
within the erectile tissue of the penis become
filled with blood. The arteries of the penis are
dilated while the veins are passively compressed
so that blood flows into the erectile cartilage
under pressure.
• The male penis is made of two different
tissues,and soft spongey tissue.
• Cartlidge is not in the penis

8. Testicles

9. Testicles
• The testes hang outside the abdominal cavity of
the male within the scrotum. They begin their
development in the abdominal cavity but
descend into the scrotal sacs during the last 2
months of fetal development. This is required
for the production of sperm because internal
body temperatures are too high to produce
viable sperm.

10. Epididymis
• The epididymis is a
whitish mass of tightly
coiled tubes cupped
against the testicles.
• It acts as a storage
place for sperm before
they enter the vasa
deferentia, tubes that
carry sperm form the
testes to the urethra.

11. Female reproductive system

12. Female reproductive system

13. Female reproductive system
Contents
• 1 Vagina
• 2 Cervix
• 3 Uterus
• 4 Oviducts
• 5 Ovaries

14. Female reproductive system
• Vagina (Latin,="sheath"or
"scabbard")
• Fibromuscular tubular tract
leading from the uterus to
the exterior of the body in
female
• “Vagina" is often used to
refer to the Vulva or female
genitals generally; strictly
speaking, the vagina is a
specific internal structure
and the vulva is the exterior
genitalia only.

15. Female reproductive system
• The vagina is the place where semen from the
male is deposited into the female's body at the
climax of sexual intercourse, commonly known
as ejaculation. Around the vagina, pubic hair
protects the vagina from infection and is a sign
of puberty

16. Female reproductive system
• Cervix
• The cervix is the lower,
narrow portion of the
uterus where it joins with
the top end of the
vagina.
• It is cylindrical or conical
in shape and protrudes
through the upper
anterior vaginal wall.
• Approximately half its
length is visible; the
remainder lies above the
vagina beyond view.

17. Female reproductive system
• Uterus
• The uterus or womb is
the major female
reproductive organ of
humans. One end, the
cervix, opens into the
vagina; the other is
connected on both sides
to the fallopian tubes.

18. UTERUS
• The uterus is a pearshaped muscular organ.
• Its major function is to
accept a fertilized ovum
which becomes implanted
into the
endometrium, and derives
nourishment from blood
vessels which develop
exclusively for this
purpose.
• The fertilized ovum
becomes an
embryo, develops into a
fetus and gestates until
childbirth.

19. OVIDUCTS
• Oviducts: Fallopian tube
• The Fallopian tubes or
oviducts are two very
fine tubes leading from
the ovaries of female
mammals into the uterus.

20. OVIDUCTS
• On maturity of an ovum, the follicle and the
ovary's wall rupture, allowing the ovum to
escape and enter the Fallopian tube.
• There it travels toward the uterus, pushed along
by movements of cilia on the inner lining of the
tubes. This trip takes hours or days.
• If the ovum is fertilized while in the Fallopian
tube, then it normally implants in the
endometrium when it reaches the uterus, which
signals the beginning of pregnancy

21. Ovaries
• The ovaries are the
place inside the
female body where
ova or eggs are
produced.
• The process by which
the ovum is released
is called ovulation.
The speed of
ovulation is periodic
and impacts directly
to the length of a
menstrual cycle.

22. • After ovulation, the
ovum is captured by
the oviduct, after
traveling down the
oviduct to the uterus,
occasionally being
fertilized on its way by
an incoming sperm,
leading to pregnancy
and the eventual birth
of a new human being.

24. Male Secondary Sex Characters
Male
– Growth of body hair, including underarm,
abdominal, chest, and pubic hair.
– Loss of scalp hair androgenic alopecia can
also occur
– Greater mass of thigh muscles in front of
the femur, rather than behind it as is
typical in mature females
– Growth of facial hair
– waist

25. Male Secondary Sex Characters
– Enlargement of larynx and deepening of
voice
– Increased stature; adult males taller than adult
females, on average
– Heavier skull and bone structure
– Increased muscle mass and strength
– Broadening of shoulders and chest; shoulders
wider than hips

26. Male Secondary Sex Characters
– Increased secretions of oil and sweat glands,
often causing acne and body odor [3]
– Coarsening or rigidity of skin texture, due to
less subcutaneous fat
– A prominent Adam's apple
• Fat deposits mainly around the abdomen
and

27. Male Secondary Sex Characters
– Higher waist to hip ratio than
prepubescent or adult females or
prepubescent males, on average
– On average, larger hands and feet than
prepubescent or adult females or
prepubescent males[citation needed]
• Lower digit ratio, on average

29. Female Secondary Sex Characters
– Enlargement of breasts
– Growth of body hair, most prominently
underarm and pubic hair
– Greater development of thigh muscles
in back (behind the femur) than in front
of it
– Vaginal and uterine growth

30. Female Secondary Sex Characters
– Decreased stature; adult females shorter stature than
adult males, on average
– Widening of hips[5]; lower waist to hip ratio than
adult males, on average
– Upper arms approximately 1" longer, on average, for
a given height[6]
– Changed distribution in weight and fat; more
subcutaneous fat and fat deposits mainly around the
buttocks, thighs and hips
• Higher digit ratio, on average

32. Gametogenesis is a process
in which diploid or haploid
cells undergo cell division and
differentiation to form mature
haploid gametes.

33. Gametogenesis
• Occurs by meiotic division of diploid gametocytes
into various gametes, or by mitotic division of haploid
gametogenous cells.
• The existence of a multicellular, haploid phase in the
life cycle between meiosis and gametogenesis is also
referred to as alternation of generations.

34. Gametogenesis is simply…
• The process of gametes
formation
• It occurs in the gonads (ovary or
testis)

36. Spermatogenesis

37. Spermatogenesis
is the process of formation of the male germ
cells (sperm formation).
It occurs in the seminiferous tubules of the
testis.
It is thread-like in shape.

39. Spermatogenesis occurs from puberty to
old age, producing immense numbers of
spermatozoa at an average rate of 1.5 million
spermatozoa per minute.
The sperm will mature in the epidiymis,
nourished by sertoli cells for up to 10 weeks.
Humans aged 13-90 can make 1 billion
sperm a day.

40. The sertoli cells are supporting cells that have several
functions.
They form the blood-testes barrier: nutrients, and circulating
substances do not directly reach the germ cells
The sertoli cells determine which substances reach the
germ cells
 The spermatogonia are outside the blood-testis barrier.
They also produce antigen-binding proteins, which are
necessary for spermiogenesis (morphological development
of spermatids to spermatozoa).

42. Spermatogenesis is the process by which male primary sperm
cells undergo meiosis, and produce a number of cells
termed spermatogonia, from which the
primary spermatocytes are derived.
Each primary spermatocyte divides into two secondary
spermatocytes, and each secondary spermatocyte into
two spermatids or young spermatozoa.
These develop into mature spermatozoa, also known
as sperm cells.
The primary spermatocyte gives rise to two cells, the secondary
spermatocytes, and the two secondary spermatocytes by their
subdivision produce four spermatozoa.

43. Oogenesis

44. Oogenesis is the process of
formation of the female germ cells (egg
formation).
It happens in the Ovary.
It is Spherical in shape.

45. Oogenesis begins in early foetal life.
All oocytes formed in females are produced during foetal life.
Many of them degenerate with time and at birth the ovaries
contain about 2 million oocytes.
All the oocytes go into meiotic arrest when they reach the first
meiotic division during foetal life.
The primary oocytes remain in the prophase of the first meiotic
division until the time of puberty, when they are gradually
released to complete meiosis at regular intervals known as the
ovarian cycle.
On the average only one oocyte matures during each cycle,
which occurs at approximately monthly intervals, so that the total
amount of oocytes to be ovulated is about 500 oocytes in a
lifetime.

47. Oogonium/Oogonia
Diploid in number: 44 autosomes
and 2 sex cells
It is very small and under the
process of development.
Undergoing G1-S.

48. Secondary Oocytes

50. Females undergo a phase called
the Menstrual Cycle

51. Physiology of menstruation
the ovaries...
• 1. Hypothalamus releases
GnRH (LHRH)
• 2. Release of GnRH triggers
APG to release FSH and LH
– FSH- responsible for the maturation
of ovum and follicle formation.
– Causes an increase in estrogen
– LH – triggers ovulation and growth
of uterine lining

52. • 2.1 FSH activates primordial follicles to mature.
• 2.2 Primordial follicles start producing follicular
fluid that is HIGH IN ESTROGEN (estradiol)
and some progesterone
• 2.3 primordial follicles propelled toward the
surface of ovary and is now called Graafian
Follicle.
– 3. Graafian follicle undergoes cell
division (mitosis, meiosis)
• 3.1 GF divides into:
– 3.1.a primary oocyte – with more cytoplasm
– 3.1.b secondary oocyte – with less cytoplasm
• 3.2 GF after meiosis contain haploid cells (23
chromosomes)

53. • 4. Upsurge in LH causes the release of
prostaglandin
• 5. Prostaglandin causes the rupture of GF
releasing ovum and follicular fluid from
the follicle, leaving the follicle with a
hollowed pit.
• 6. Increase in LH causes production of
Lutein (bright yellow fluid, HIGH IN
PROGESTERONE) that will fill the
empty pit
• 7. Follicle becomes “CORPUS
LUTEUM”

54. – 7.1 if fertilization occurs, ovum
implants at the uterus, corpus luteum
stays inside the ovaries until 16-20
weeks; trophoblast begin secreting
HCG
– 7.2 without fertilization, ovum
atrophies after 4-5 days, CL remains
for only 8-10 days.
– 7.2.a CL replaced by white fibrous
tissue, CL becomes “CORPUS
ALBICANS”

55. Physiology of menstruation
the uterus...
1st PHASE: PROLIFERATIVE
(aka
estrogenic/follicular/postmenstrual
)
High levels of estrogen causes
thickening and proliferation of
endometrium
LH is increased, Estrogen is
increased

56. 2nd PHASE: SECRETORY (aka:
progestational/luteal/premenstrual)
 Increased levels of progesterone
causes glands at endometrium to
become cork screw like or twisted in
appearance and dilated with
quantities of glycogen and mucin
 Increased in capillaries making
endometrium appear like a rich
spongy velvet
 Decreased LH, Increased
Progesterone

57. 3RD PHASE: ISCHEMIC
Decreased estrogen and
progesterone levels causes the
degeneration of the
endometrium
Capillaries rupture,
endometrium sloughs off

58. 4TH PHASE:
MENSES/MENSTRUAL
FLOW
menses is composed of:
 Blood from the ruptured capillaries
 Fragments of endometrial tissue
 Microscopic, atrophied, unfertilized
ovum

60. Physiology of menstruation
the cervix...
1 half of the cycle
st
 Hormones decreased
 Mucus thick and scanty
 Poor sperm survival
Ovulation
 Estrogen is increased
 Cervical mucus thin and copious
 Excellent sperm survival
2nd half
 Decreased progesterone level
 Mucus is thick
 Poor sperm survival

62. Hormones in the menstrual
cycle

63. Pituitary gland

64. Pituitary gland

65. Pituitary gland
Secretes FSH –
starts the cycle

66. Pituitary gland
Secretes FSH –
starts the cycle
FSH causes the ovary to develop
an egg and release oestrogen

67. Pituitary gland
Secretes FSH –
starts the cycle
Oestrogen inhibits
production of FSH
FSH causes the ovary to develop
an egg and release oestrogen

68. Pituitary gland
Secretes FSH –
starts the cycle
Oestrogen inhibits
production of FSH
Stimulates
release of LH
FSH causes the ovary to develop
an egg and release oestrogen
Lining of the uterus
thickens

69. Pituitary gland
Secretes FSH –
starts the cycle
Secretes LH
Oestrogen inhibits
production of FSH
Stimulates
release of LH
FSH causes the ovary to develop
an egg and release oestrogen
Lining of the uterus
thickens

70. Pituitary gland
Secretes FSH –
starts the cycle
Secretes LH
Oestrogen inhibits
production of FSH
Stimulates
release of LH
LH causes ovulation
and releases
progesterone
FSH causes the ovary to develop
an egg and release oestrogen
Lining of the uterus
thickens

71. Fertilization,
Implantation &
Development and
Gestation

72. Fertilization
the fusion of the sperm cell
nucleus with the egg cell
nucleus to produce a zygote
(fertilized egg)

73. Fertilization:
• External
• Occurs outside of the body of the female
• Increased number of eggs produced to insure
the survival of the species
• Ex) fish and amphibians

74. Fertilization:
•
•
•
•
•
Internal
Occurs inside the body of the female
Fewer number of eggs are produced
Increased parental care insures species survival
Ex) mammals, reptiles, birds

75. Fertilization:
• fertilization in
mammals occurs
in the oviduct
• The ova is viable
for
approximately 24
hours after
ovulation

77. Implantation
• After approximately a
week, the developing
embryo is implanted
into the uterus
• Embryo: conception
to 8 weeks

78. Embryonic Development

79. Embryo:
• a multicellular organism in the early stages of
development
2 four cell stage embryos
Eight cell stage embryo

80. Embryo:
The beginning developmental processes are always
the same in all animals:
1) cleavage
2) growth
3) differentiation

81. Embryo:
• after fertilization
the diploid
ZYGOTE
undergoes cleavage
divisions in the
oviduct

82. Cleavage
the first series of cell divisions by mitosis
after fertilization
Cell division is rapid, new cells do not take
time for the growth phase G1
cell growth does not occur so cells
decrease in size with each cleavage
division

83. Cleavage divisions

84. • Morula forms (solid ball of cells)
• Blastula forms (hollow ball of cells)
• Cells begin to grow before dividing

86. Differentation
• Gastrulation: one side
of the blastula
invaginates (indents)
forming a gastrula
• Three cell layers form

87. Differentation

88. Differentiation
• The changing of unspecialized embryonic cells
into the specialized cells, tissues and organs of a
multicellular animal

89. Germ Layers
• Ectoderm
Outer layer
• Nervous system including brain, spinal cord
and nerves
• Lining of the mouth, nostrils, and anus
• Epidermis of skin, sweat glands, hair, nails

90. Germ Layers
•
•
•
•
•
Mesoderm Middle Layer
Bones and muscles
Blood and blood vessels
Reproductive and excretory systems
Inner layer (dermis) of skin

91. Germ Layers
•
•
•
•
•
Endoderm Inner Layer
Lining of digestive tract
Lining of trachea, bronchi, and lungs
Liver, pancreas
Thyroid, parathyroid, thymus, urinary bladder

92. Placenta
• organ that
forms from the
embryo and the
uterus
• contains blood
vessels from the
mother and the
developing baby

93. Placenta
• Oxygen & nutrients diffuse from the
mother’s blood vessels into the baby’s
blood vessels
• Wastes diffuse from the baby’s blood
vessels into the mother’s blood vessels

94. Umbilical Cord
• two arteries and a
vein Connects the
fetus to the placenta

95. Amniotic Sac
• Contains fluid
(amniotic fluid) that
protects fetus by
giving it a stable
environment and
absorbing shock

96. • By the end of the 8th
week of pregnancy the
embryo is called a fetus
and all of the major
structures are present

97. Later Stages of Fetal
Development

98. Human gestation
• the period between
fertilization and
birth
• approximately 3840 weeks

99. Teratogens
• Substances that may harm the developing
fetus and result in the formation of birth
defects

100. Teratogens include:
• Alcohol, certain drugs/medications,
infections, and certain chemicals

102. Fetal Alcohol Syndrome
Can result in mental retardation / learning disability
Facial Features
• Epicanthal folds
• Small, widely spaced eyes
• Flat midface
• Short, upturned nose
• Smooth, wide philtrum
• Thin upper lip
• Underdeveloped jaw

103. Cleft Lip / Palate
• maternal alcohol consumption and maternal smoking
during the early stages of pregnancy have been shown
to increase the risk of developing orofacial clefts
•
http://www.hopeforkids.com/body_cleft_lip%5B1%5D.html#

104. How do twins form???

105. Monozygotic Twins
(Identical Twins)
• One egg is fertilized by one sperm
• Embryo splits into two during the early stages of
development
• Have identical genes and must be of the same sex
• (Incidence: about 3 in every 1000 births)

106. Dizygotic Twins
(Fraternal Twins)
• Two eggs are ovulated and each is fertilized by a sperm
cell
• No more genetically similar than any other sibling in
the family (can be same/different sexes)
• Maternal age, use of assisted reproductive technologies
are factors
• Incidence (6.7/1000 births in Japan to 40/1000 births
in Nigeria)

108. LIST OF REFERENCES:
Bhondwe, A., 2010, Human Reproductive System (Slide-share), viewed 06 March
2014, from http://www.slideshare.net/avinash15/human-reproductivesystem?qid=3d348044-a0b8-4ba6-a91071d505e688a6&v=qf1&b=&from_search=7
Bishop, S., 2014, Hormones in The Menstrual Cycle (Slide-share), viewed 07 March
2014, from http://www.slideshare.net/sbishop2/hormones-in-the-menstrualcycle-30343967?qid=1ddce368-24ed-4883-9a598328e935edbe&v=default&b=&from_search=10
Jardin. D. M., Anatomical Chart of Human Reproductive Systems (picture used),
viewed and utilized on 09 March 2014, taken from
http://www.flickr.com/photos/mdesjardin/4331654523/sizes/z/in/photostr
eam/
Mehta, G., 2013, Gametogenesis (Slide-share), veiwed 07 March 2014, from
http://www.slideshare.net/gunjan_rjt/gametogenesis16584337?qid=d7246b19-e486-4aa1-bf5639fed46875b8&v=qf1&b=&from_search=5
Rakiraks, Z., 2010, The Menstrual Cycle (Slides-hare), viewed 09 March 2014,
from http://www.slideshare.net/rakiraksz/the-menstrual-cycle?qid=8528509e2a29-407b-bbde-8af437617f37&v=qf1&b=&from_search=5