gametogenesis,embryology

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.