embryology, formation of embryo, morula, blastocyst, trophoblast, development of inner cell mass, germs layer, fetal development, week - 1 to week - 40 development of the fetus.

1. DOLISHA WARBI

2. Karl Ernst Von Baer is the father of Modern Embryology.
Embryology is a branch of biology that deals with gamete formation
fusions of gametes and embryo formation.

3. qThe ovum immediately following evolutions is pick up by the tubal
fimbria especially at the time of ovulations.
qThe ovary is transported to the ampulla part.
qIt keeps one hour for the sperm to reach the site.
qMore than one sperm penetrate the zona pellucida, out of many sperm,
1 touched the vitelline membrane.
qThe male and the female pronuclei unite at the center with restorations
of diploid number of chromosome, which is constants for the species.
qThe Zygote, thus form contain both the paternal and maternal genetics
materials.
qThe sex of the child is determined by the pattern of the sex
chromosome supplied by the spermatozoa.

4. .

5. The two cell stage is reached approximately 30 hours after fertilization.
Each contain equals cytoplasmic volumes and chromosome number.
The blastomeres continue to divide by Binary Division through 4, 8, 16
cells stage until a cluster of cell is formed, and its called morula.
The central of Morula is known as Inner cell mass, which formed the
embryo proper and the peripheral cells are called outer cell mass, which
will form the protective and nutritive membranes of the embryo.

6. While the Morula remains free in the uterine cavity on the 4th and the 5th
day, it covered by a film of mucus.
The fluid passes through the Canaliculi of the zona Pellucida, which
separate the cell of the morula and is termed as blastocyst.
The zona pellucida disappear.
The cell of the outer cell mass formed the wall of the blastocysts and are
known as trophoblasts, which is concerned with the embedded and
attachments of zygote.
The inner cell mass is concerned with the development of embryo.

7. The cell of the blastocyst differentiated into an outer trophoblast and inner
cell mass.
Just before implantation, the trophoblast is further differentiated into an
inner cellular layer called the cytotrophoblast.
The outer layer of multinucleated, syncytium called plasmodia trophoblast.
Placenta and fetal membrane are developed from the trophoblast.
Trophoblast serve 3 important function invasions, nutrition and production
of hormones for the maintenance of pregnancy.

8. Two cavities one on each side of the germ disk these are;
The fluid space which appears between the ectodermal layer and the
cytotrophoblast is called amniotic cavity. Its floor is formed by the ectoderm
and the rest of its wall by primitive mesenchyme.
The cavity, which appears on the ventral aspect of the bilaminar disk is known
as yolk sac.
THE THREE GERMS LAYERS ARE:
1) ECTODERM – In general form exterior tissue, including - Central and
peripheral nervous system, epidermis of the skin, which is appendages,
pituitary gland, salivary gland, mucus lining of the nasal cavity, paranasal
sinus, roof of the mouth.
2) MESODERM – In general form, Structural tissues, including – muscle, bones,
cartilages, kidney, spleen, circulatory system and reproductive system.
3) ENDODERM – In general form, internal organs, including - digestive system,
liver, pancreases, epithelial lining of respiratory tract and most of the
mucous membrane of urinary bladder and urethra and endocrine gland.

9. .

10. § A. Pre-embryonic period: First 2 weeks after conception.
§ B. Embryonic period: Beginning at day 15 through approximately the eighth
week after conception.
§ C. Fetal period: Beginning at the ninth week after conception and ending
with birth.
WEEK 1
§ Blastocyst is free-floating.
§ Embryo is 1.5 to 2 mm in length.
§ Lung buds appear.
§ Blood circulation begins.
§ Heart is tubular and begins to beat.
§ Neural plate becomes brain and spinal cord.

11. WEEK 5
§ Embryo is 0.4 to 0.5 cm in length.
§ Embryo is 0.4 g.
§ Double heart chambers are visible.
§ Heart is beating.
§ Limb buds form.
WEEK 8
§ Embryo is 3 cm in length.
§ Embryo is 2 g.
§ Eyelids begin to fuse.
§ Circulatory system through umbilical
cord is well established.
§ Every organ system is present.

12. WEEK 12
§ Fetus is 6 to 9 cm in length.
§ Fetus is 19 g.
§ Face is well formed.
§ Limbs are long and slender.
§ Kidneys begin to form urine.
§ Spontaneous movements occur.
§ Heartbeat is detected by Doppler transducer between 10 and 12 weeks.
§ Sex is visually recognizable.

13. WEEK 16
§ Fetus is 11.5 to 13.5 cm in length.
§ Fetus is 100 g.
§ Active movements are present.
§ Fetal skin is transparent.
§ Lanugo hair begins to develop.
§ Skeletal ossification occurs.
WEEK 20
§ Fetus is 16 to 18.5 cm in length.
§ Fetus is 300 g.
§ Lanugo covers the entire body.
§ Fetus has nails.

14. WEEK 20 CONT..
§ Muscles are developed.
§ Enamel and dentin are depositing.
§ Heartbeat is detected by regular (nonelectronic) fetoscope.
WEEK 24
§ Fetus is 23 cm in length.
§ Fetus is 600 g.
§ Hair on head is well formed.
§ Skin is reddish and wrinkled.
§ Reflex hand grasp functions.
§ Vernix caseosa covers entire body.
§ Fetus has ability to hear.

15. WEEK 28
§ Fetus is 27 cm in length.
§ Fetus is 1100 g.
§ Limbs are well flexed.
§ Brain is developing rapidly.
§ Eyelids open and close.
§ Lungs are developed sufficiently to provide gas exchange(lecithin forming).
§ If born, neonate can breathe at this time.
WEEK 32
§ Fetus is 31 cm in length.
§ Fetus is 1800 to 2100 g.
§ Bones are fully developed.
§ Subcutaneous fat has collected.
§ Lecithin-to-sphingomyelin (L/S) ratio is 1.2:1.

16. WEEK 36
§ Fetus is 35 cm in length.
§ Fetus is 2200 to 2900 g.
§ Skin is pink and body is rounded.
§ Skin is less wrinkled.
§ Lanugo is disappearing.
§ L/S ratio is greater than 2:1.

17. WEEK 40
§ Fetus is 40 cm in length.
§ Fetus is more than 3200 g.
§ Skin is pinkish and smooth.
§ Lanugo is present on upper arms and shoulders.
§ Vernix caseosa decreases.
§ Fingernails extend beyond fingertips.
§ Sole (plantar) creases run down to the heel.
§ Testes are in the scrotum.
§ Labia majora are well developed.