PERKEMBANGAN BAYI

2.1 Embryology, human fetal development and parturition process

EmbryologyDefinisi: Kajian tentang asal-usul dan perkembangan organisma

Stage 1:Persenyawaan

1. Enzim yang terkandung dalam akrosom melarutkan lapisan jeli pada sel telur

2. Membran sperma bergabung dengan membran sel telur, membenarkan nukleus sperma masuk

3. Sperma lain dihalang memasuki sel telur

4. Nukleus sel telur bercantum dengan nukleus sperma

PERSENYAWAAN• SPERMA + OVUM(OOCYTE) = ZIGOT

• Proses persenyawaan mengambil masa 24 jam

• J/hayat sperma = 48 jam– Sperma mengambil masa 10 jam untuk ke tempat

persenyawaan di tiub falopian

– Conception (biology) or fertilisation, the fusion of gametes to produce a new organism of the same species (Wikipedia)

Mr.SPERM + Mrs. EGG

PERSENYAWAAN….

• 300 juta sperma memasuki vagina... Hanya 1%, 3 juta sahaja, berjaya memasuki uterus

• Selepas itu fasa penembusan zon pellucida, lapisan membran yang mengelilingi ovum/oocyte.

• Mengambil masa lebih kurang 20 minit.

Persenyawaan….

• Dalam masa 11 jam selepas persenyawaan, penghasilan zigot adalah penamat bagi proses persenyawaan.

• Perkembangan seterusnya terbahagi kepada 3 peringkat:

• Pembelahan/Cleavage: pembahagian zigot kepada beberapa sel anak

• Gastrulasi: penyusunan sel-sel kepada beberapa lapisan

• Organogeni: pembentukan organ dan sistem organ.

Persenyawaan kepada Penempelan:

Pembelahan/Cleavage

Beberapa siri pembahagian sel secara mitosis di mana sitoplasma sel telur dibahagi kepada sel-sel yang lebih kecil dipanggil blastomer/blastosist.

Pembelahan

• Morula – (1.5-3 hari selepas persenyawaan) bebola yang padat dengan sel-sel

• Blastula – (4 hari selepas persenyawaan) bebola sel yang mempunyai ruangan kosong , dipenuhi dengan cecair yang dipanggil blastosol

Blastocyst stage• Blastosist akan terapung-apung di dalam uterus

selama lebih kurang 3 hari.• Penempelan berlaku pada hari ke 6-7 selepas

persenyawaan– Trophoblast erodes uterine wall– Takes 1 week to complete

Penempelan

• Paras HCG/ "Human Chorionic Gonadotropin" meningkat

• 0.1 - 0.2 mm• 5 - 6 hari selepas persenyawaan• The trophoblast cells secretes an enzyme

which erodes the epithelial uterine lining and creates an implantation site for the blastocyst.

Hari 7-10

• Bebola sel terbahagi kepada 2 karung/rongga berisi cecair:

– rongga amnion

– Pundi bekalan lembaga

Penempelan Luar Biasa

Hari 10-14: Gastrulation

• “It is not birth, marriage or death,but gastrulation, which is truly the most important time in your life.”        Lewis Wolpert (1986)

-Ectoderm: skin, nervous system-Endoderm: lining of gut and internal organs -Mesoderm: muscles, bones, heart

Three Primary Germ Layers

• Ectoderm – outermost layer, becomes the skin, CNS, sense organs

• Mesoderm – middle layer, becomes skeleton, muscles, blood vessels, heart, gonads

• Endoderm – inner layer, becomes digestive tract, lungs, glands

Hari 15-21

Neural groove (future spinal cord and brain) begins to formSomites (bands of tissue that will become muscles and bones) begin to form

Organogenesis

• Organogenesis (development of the organs and organ systems) begins with the nervous system

• most organogenesis has begun as early as week five in humans (embrio)

Hari 21….seterus

• Forebrain, midbrain and hindbrain.

• Forebrain senses, memory formation, thinking, reasoning, problem solving.

• Midbrain relay station, coordinating messages to their final destination

• Hindbrain regulates the heart, breathing and muscle movements

Early 4th week

Pharangeal arches (menjadi muka, leher, mulut, hidung) mula terbentuk

• Lymphatic & thyroid start to develop

• Limb buds

• First thin layer of skin

• Liver & heart, etc.

28 days

• approximately 41 postovulatory days

• A Four Chambered Heart and a Sense of Smell

• Primitive germ cells arrive at the genital area and will respond to genetic instructions to develop into either female or male genitals.

41 days

• 48-52 days post ovulation

• Spontaneous Involuntary Movement

• Brain is connected to tiny muscles and nerves and enables the embryo to make spontaneous movements

• Testes or ovaries are distinguishable

51 days

Stage 23

• approximately 56 - 57 postovular days

• Essential External and Internal Structures Complete

• Layer of rather flattened cells, the precursor of the surface layer of the skin, replaces the thin ectoderm of the embryo. Tail has disappeared.

56days

9weeks

Week 12 - 13

• Fetus begins to move

• Heartbeat can be found with doppler

• Fetal sex now clearly distinguished

• Body begins to grow hair

Minggu 16

• Growth continues, but no new structures form after this point

• Meconium begins to accumulate in the bowels. Meconium is the product of cell loss, digestive secretion and swallowed amniotic fluid.

• Placenta equal in size to fetus

17 week

Week 20

• Fetus sucks thumb• Extremely rapid brain growth (which lasts

until five years after birth) begins.

• Testes of male fetuses begin descending from the pelvis into the scrotum.

• Arms and legs move with more force, as muscles strengthen.

Love that thumb!

Week 26

• Lungs may be mature enough to breath air!• Fetal body is two to three percent body fat.

• Eyes are partially open and eyelashes present.

• Sucking and swallowing improves.

Week 32

• Fetus rests on uterus - no longer floating.

• Eyes open during alert times and close during sleep. Eye color is usually blue, regardless of the permanent color as pigmentation is not fully developed

Week 34

• Head may now position (head-down) into pelvis before labor.

• Gastrointestinal system is very immature and will stay that way until three or fourth years after birth.

• Fetus stores about 15% of weight in fat to keep temperature of body warm

Week 34

• Head may now position (head-down) into pelvis before labor.

• Gastrointestinal system is very immature and will stay that way until three or fourth years after birth.

• Fetus stores about 15% of weight in fat to keep temperature of body warm

40 weeks

• Fullterm

• Fifteen percent of body is fat, eighty percent of which is underneath the skin, the other twenty percent around the organs.

Partruition....

Fetal development