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EMBRYOLOGY
Is the study
of human development.
GAMETOGENESIS• Is the process of formation and development
of gametes.
• Gametes are highly specialized sex cells
in male---------Sperms.
in female---------Oocyte (ovum).
• Gamete contains half the number of chromosomes present in any body cell (Haploid Number of chromosomes).
GAMETOGENESIS
• Normal somatic cell = 46 chromosomes (diploid)
• Gamete = 23 chromosomes (haploid)
• Male gamete (23) + female gamete (23)-------- zygote (46)
• The reduction of chromosome number occur during reduction division called MEIOSIS
CELL DIVISION• MITOTIC DIVISION
1. Occurs in whole body cells (somatic cell)
2. Each somatic cell contain 46 chromosomes (diploid number of chromosomes).
2. Each cell------ 2 cells.3. Daughter cells contain
diploid number of chromosome (46).
4. Is for growth and repair.
Cell divisionMEIOTIC DIVISION
• Occurs in sex cells in testis and ovary----- (Spermatogonia) in male & (Oogonia) in female.
• 2. A permatogonia------ 4 sperms.
• One oogonia-------- one oocyte.
• 3. Daughter cells contain haploid number (23) of chromosome.
• 4. Provide a constancy of chromosomes from generation to generation.
GAMETOGENESIS I. SPERMATOGENESIS
(formation of sperm)1. Begins at puberty till very
old age.2. Occur at all time .3. Spermatogonia (sex cell) is
present in testis in all ages.4. Stages are: • Spermatogonia (46) • 1ry spermatocyte (46)• 2ry spermatocytes (23)• Spermatids (23) • Sperms (23)
GAMETOGENESIS
II. OOGENESIS (formation of the ovum)
1. 1st meiotic division begins at 3rd month prenatal life---- arrested till puberty.
At birth NO OOGONIA exist in the ovary.
2. Division resumed at puberty ---till menopause.
Stop at menopause.
3. Stages are: • Oogonia (46)• Iry oocyte (46) • 2ry oocyte (23)• Mature oocyte (23)
Oogenesis
GAMETOGENESIS
SPERMATOGENESIS1. Begins at puberty till
very old age.2. Occur at all time .3. Spermatogonia is present
in testis in all ages.4. Stages are: • Spermatogonia (46) • 1ry spermatocyte (46)• 2ry spermatocytes (23)• Spermatids (23) • Sperms (23)
OOGENESIS1. Begins at prenatal life----
arrested till puberty.2. Stop at menopause.3. At birth NO OOGONIA
exist in the ovary.4. Stages are: • Oogonia (46)• Iry oocyte (46) • 2ry oocyte (23)• Mature oocyte (23)
Sperm
Gametes
Oocyte (ovum)• Massive cell.• Immotile.• One ovum is formed
each month from puberty till menopause.
• Chromosome= 22 + x chromosome (23)
Sperm• Small, scanty
cytoplasm.• Number in millions, all
days, all time from puberty till very old age.
• Chromosome 2 types:22+x chromosome(23)22+y chromosome(23)
QUIZ
• Normal complement of chromosome in a sperm is ?
a) 22 autosomes + sex chromosome.
b) 23 autosomes + sex chromosome.
c) 22 autosomes.
d) 46 chromosomes.
e) 23 autosomes.