Gametogenesis
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Transcript of Gametogenesis
Gametogenesis
Physiology of reproductive system
Ms. Beatriz Duro 3º ESO
Human genetic material
• DNA is a large molecule
which coils up into a
structure called
chromosome when the
cell is about to divide.
– When the cell is not
dividing it is loose in the
nucleus in the form of
chromatin.
• DNA contains the genetic
information which
controls cell processes.
Human genetic material
• All human somatic
cells have 46
chromosomes (23
pairs).
– Diploid cells: cells with
pairs of chromosomes.
• Gamets have 23
chromosomes in total.
– Haploid cells: cells with
only one chromosome
of each type.
This is the
human
karyotype
Human cell division
Somatic cells (2n) divide
to form two identical cells
(2n) of the same kind
through mitosis
A special somatic cell (2n)
divides to form four cells
with half the genetic
material (n) through
meiosis
2 types of cell
division:
Spermatogenesis
Growth and
replication of DNA
Meiosis
Maturation
Spermatogenesis
• Maturation
– Takes place in the
epididymis.
– The cell elongates.
– The cytoplasm is reduced.
– The nucleus is set at the
front of the cell together
with the acrosome.
– The flagellum is formed.
Male gamet: sperm
Female gamet: ovum
Oogenesis
Ovarian cycle
Follicularphase
Caused by the secretion of FSH by the pituitary gland.
Lasts 14 days
Various follicles begin to develop, however only one matures
Ovulation The ovum is released by the ovary.
Cause by the presence of LH
The body temperature increases 0.5ºC
Lutealphase
The area where the ovum was, tranforms into a mass of cells: corpus luteum.
Corpus luteum secretes progesterone for 10-12 days.
When it stops secreting hormone the cycle begins again.
Begining of thecycle.
Sharp decrease in the amount of hormones secretedby the ovaries.
Vascularized uterinewall is shed and expelled from thebody: period.
Lasts 4-5 days
Menstrual phase (Period)
Uterine wall is rebuiltthanks to estrogensproduced by theovaries.
Lasts 11 days.
Proliferativephase
Uterine lining is at itsmaximum thickness, ready to receivefertilised egg.
Due to theprogesteronesecreted by theovaries.
Lasts 12 days iffertilization does notoccur
Secretoryphase (Luteal)
Uterine cycle
Menstrual and Ovarian cycles