Characteristics of human reproduction.
Human reproduction is…
ovum and the…
spermatozoid are joined it formes
the zygote, which forms an…
The union of these cells is called…
The ovum is formed in the…
And the spermatozoid in the… testicles.
Both of them are called…
Changes during growth
Primary sexual characteristics: Present at birth.
Secondary sexual characteristics: appears in the maturity.
This changes occurs during a very specifc age which is known as puberty and are
the result of the action of sexual hormons.
Changes during puberty
• In the female:
• Pubic hair and hair under the arms.
• Distribution of body fats.
• Development os mammary glands.
• In the male:
• The development of public hair.
• The beard and hair over a large part of the body.
• An increase in the bones and muscles, change of voice, etc.
Diagram of human reproduction.
Female gonads: Ovaries
Lie in the abdominal cavity
Each ovary contains
many follicles, which consist of a partially
developed egg, called an oocyte, surrounded by
Once a month, an oocyte develops into an ovum
(egg) by the process of oogenesis
Ovulation is the release of an egg cell from the
The remaining follicular tissue grows within the
ovary, forming the corpus luteum.
The corpus luteum secretes hormones e.g. that
help to maintain pregnancy.
If the egg is not fertilized, the corpus luteum
After ovulation, the egg cell travels from the
ovary to the uterus via an oviduct, or fallopian
Cilia in the oviduct convey the egg to the
uterus, also called the womb.
The uterus lining, the endometrium, has many
The uterus narrows at the cervix, then opens
into the vagina.
The vagina: is a thin-walled chamber that is
the repository for sperm during copulation
and serves as the birth canal
The vagina opens to the outside at the vulva,
which consists of the
The mammary glands are not part of the reproductive
system but are important to mammalian reproduction.
Within the glands, small sacs of epithelial tissue secrete
Male Reproductive Anatomy
The male’s external reproductive organs are:
the scrotum and penis
Male Reproductive Anatomy
Internal organs are:
the gonads (testes), which produce sperm and
and accessory glands
Male gonads: Testes
Testes, consist of:
highly coiled seminiferous tubules (in which sperm form)
surrounded by connective tissue
Leydig cells produce hormones and are scattered between
Production of normal sperm cannot occur
at the body temperatures .
The testes are held outside the abdominal
cavity in the scrotum, where the
temperature is 2ºC lower than in the
From the seminiferous tubules of a testis,
sperm pass into the coiled tubules of the
During ejaculation, sperm are propelled
through the muscular vas deferens and the
ejaculatory duct, and then exit the penis
through the urethra.
Semen is composed of:
secretions from three sets of accessory glands
The two seminal vesicles contribute about 60%
of the total volume of semen.
The prostate gland secretes its products directly
into the urethra through several small ducts.
The bulbourethral glands secrete a clear
mucus before ejaculation that neutralizes
acidic urine remaining in the urethra.
The human penis is composed of three
cylinders of spongy erectile tissue.
During sexual arousal, the erectile tissue
fills with blood from the arteries, causing
The head of the penis is called the glans
and is covered with a prepuce.
The rest is called the shaft.
Passage of a sperm through the corona radiata.
Dispersal of the follicular cells of the corona
radiata surrounding the oocyte and zona
enzyme hyaluronidase released from the
acrosome of the sperm, tubal mucosal enzymes
and movements of the tail of the sperm are
important in its penetration of the corona
Penetration of the zona pellucida. Passage of a sperm
through the zona pellucida.
The enzymes esterases, acrosin, and neuraminidase
appear to cause lysis of the zona pellucida, thereby
forming a path for the sperm to follow to the oocyte.
Once the sperm penetrates the zona pellucida, a zona
reaction-a change in the properties of the zona pellucida-
occurs making it impermeable to other sperms. The zona
reaction is believed to result from the action of lysosomal
enzymes released by cortical granules near the plasma
membrane of the oocyte.
Fusion of plasma membranes of the oocyte
The plasma or cell membranes of the
oocyte and sperm fuse and break down at
the area of fusion.
The head and tail of the sperm enter the
cytoplasm of the oocyte, but the sperm's
plasma membrane remains behind
Completion of the second meiotic
division of oocyte and formation of
female pronucleus. Penetration of the
oocyte by a sperm activates the oocyte
into completing the second meiotic
division and forming a mature oocyte
and a second polar body
Following decondensation of the
maternal chromosomes, the nucleus of
the mature oocyte becomes the female
Formation of the male pronucleus. Within
the cytoplasm of the oocyte, the nucleus
of the sperm enlarges to form the male
pronucleus and the tail of the sperm
Morphologically, the male and female
pronuclei are indistinguishable. During
growth of the pronuclei, they replicate
their DNA-1 n (haploid), 2 c (two
chromatids). The oocyte containing two
haploid pronuclei is called an ootid.
As the pronuclei fuse into a single
diploid aggregation of
chromosomes, the ootid becomes a
zygote. The chromosomes in the
zygote become arranged on a
cleavage spindle in preparation for
cleavage of the zygote
As the pronuclei fuse into a single
diploid aggregation of chromosomes,
the ootid becomes a zygote. The
chromosomes in the zygote become
arranged on a cleavage spindle in
preparation for cleavage of the zygote
1. Restoration of the diploid number of chromosomes.
2. Determination of the sex of the new individual.
3. Initiation of cleavage.
4. Trasportation of gentic features of parentes.
Results of Fertilization
Human embryo development is viviparous because it
is carried in the mother's womb.
The zygote leaves the fallopian tube and goes to the
uterus. It gets stuck to the wall and starts growing
It is now called embryo.
The embryo remains in the mother's womb for about
It is the time the embryo remains in the mothers womb
for nine months.
We divide this period into three trimesters.
● The embryo is surrounded and protected by a sack full
of liquid, the amnion.
● The embrio produces and organ called placenta. This
placenta extracts nutrients and oxygen from the
● These oxygen and nutrients reach the embryo through
a conduct: the umbilical cord.
● The embryo is called now a foetus.
● The skelleton, musculature and organs develope.
● At the end of the seventh month, all the foetus' organs
are already sufficiently developed for it to survive
outside the mother.
● From this moment until the ninth month it gains weigh
and fits the head into the neck of the uterus. It is ready
to be born.
When the baby is ready, the muscles of the uterus
The amnion breaks and the baby comes out of the
The remains of the cord leave a scar on the abdomen
of the baby: the navel.
Human Reproduction. Human reproduction; anatomy, cells,
hormones, pregnancy. Paqelena. 20.04.2009
Human reproduction. Female and Male Reproductive anatomy.
Human reproductionPresentación sobre la reproducción
humana para alumnos de 6º de primaria. Damarbe.
Fertilization. Including all stages and events of fertilization and
formation of embryo. Reda Cheema. 23.11.2012
Fertilization. Rashid Ahmed. 30.01.2012