Mod.A Embryology Lec1

Question 1

Spermatogenesis (aim, site, duration)

Answer 1

Aim. Formation of sperms with haploid
number of chromosomes 23X or 23Y.

Site. In the seminiferous tubules of the testis.

Duration. From puberty till death.

Question 2

Steps of spermatogenesis;

Answer 2

1-proliferation
2-growth
3-maturation
4-transformation

Question 3

1- proliferation:

Answer 3

It Means increase in the number of the cells.

Spermatogonia (which have diploid
number of chromosomes 46XY), divided by
MITOSIS into 2 daughter spermatogonia
which have also diploid number of
chromosomes.

Question 4

2- Growth:

Answer 4

each daughter spermatogonia enlarges in size forming primary spermatocyte

Question 5

3-Maturation

Answer 5

1st maturation division:
each primary spermatocyte divides by meiosis into 2 secondary spermatocytes (haploid 23X or 23Y)

2nd maturation divi4-sion:
each secondary spermatocyte divides by mitosis(meiosis II) into 2 spermatids (haploid)

Question 6

4-Transformation, spermiogenesis:

Answer 6

􀂃 Nucleus = head.
􀂃 Golgi = acrosamal cap.
􀂃 Centeriols = axial filament.
􀂃 Mitochonderia = helical sheath.

Question 7

The sperms undergo maturation in the?

Answer 7

epididymis for about 60-64 days,

then stored in the ampulla of vas defferens.

If not ejaculated, they die and become absorbed.

Question 8

Sperm (length, formed of)

Answer 8

Total length=60 μ

Formed of:
1- Head which contains
􀂃 Nucleus with haploid number of
chromosomes which carry the
genetic characters.
􀂃 Acrosomal cap. Secretes enzymes
which facilitate penetration of the
ovum.

2- Neck.

3- Body or middle piece. Contain
mitochondrial sheath which produce
energy for motility.

4- Tail .

Question 9

Characters of the sperms

Answer 9

Viability: Sperm remain viable for 1-2 days in the female
genital tract.

􀂃 Mobility: At least 70% are mobile.

􀂃 Abnormal forms: Should not be more than 10%.

􀂃 Abnormal forms as giant, dwarf or joined sperm.

Question 10

Semen (source) (volume) (count)

Answer 10

1- Sperms from the testes
2- Secretions of the seminal vesicles, prostate, bulbourethral
glands and urethral glands.

volume 3-5ml

sperm count: 100 million

Question 11

Necrospermia

Answer 11

dead sperms.

Question 12

Oligospermia

Answer 12

low sperm count.

Question 13

Azospermia

Answer 13

absence of sperms.

Question 14

Semen analysis (importance)

Answer 14

diagnosis of evaluating patient with

male infertility.

Question 15

male infertility:

Answer 15

a man with less than 15M sperm/ml and 40% total
motility is diagnosed with male
infertility.

Question 16

types of male infertility:

Answer 16

Male infertility can be either
diagnosed as

insufficient numbers of
sperm in the ejaculate
(oligozoospermia)

absence of
sperm (azoospermia)

poor sperm motility (asthenozoospermia)

decreased normal morphology
(teratozoospermia).

Question 17

Oogenesis (aim, site, duration)

Answer 17

Aim. Formation of ovum ( single large and haploid)

Site. In the ovary . Each ovary produce one ovum every 2 months.

Duration. From intrauterine life till menopause

Question 18

Steps of oogenesis:

Answer 18

Two prenatal stages occur in intrauterine life

proliferation

growth

maturation

Question 19

proliferation.(oogenesis)

Answer 19

Oogonia with diploid number of chromosomes 46XX divided by mitosis giving 2 daughter oogonia.

Question 20

growth.(oogenesis)

Answer 20

The daughter oogonia enlarge forming primary oocytes .
Each primary oocyte become surrounded by follicular
cells forming a primordial follicle, further changes are
arrested till puberty.

Question 21

when does maturation occur in oogenesis

Answer 21

after maturation

Question 22

maturation.(oogenesis)

Answer 22

occurs once per month

5-15 primordial follicles begins to grow, one only
continues maturation and the rest degenerate
forming atretic follicles.

1- First maturation division
The primary (1ry) oocyte divided by meiosis giving
secondary oocyte and first polar body.

2- Second maturation division
It occurs after ovulation and only if fertilization occur.
The 2ry oocyte divided by mitosis into mature ovum
and second polar body which extruded to the
perivitelline space and degenerate.