Prenatal Development (Embryo and Fetus) PDF

Prenatal Development (Embryo and Fetus) E. Suryadi, Anatomy, Embryology and Anthropology Department 1  Steps of prenatal development 1. fertilizationzigote 2. segmentationmorula 3.Blastulationblastula 4....

Prenatal Development (Embryo and Fetus) E. Suryadi, Anatomy, Embryology and Anthropology Department 1  Steps of prenatal development 1. fertilizationzigote 2. segmentationmorula 3.Blastulationblastula 4. Gastrulation/gastrula Implantation 5. Embryogenetic /embryo Placentation 6. Organs system maturation /fetus 2  Beberapa proses pada embryogenesis 1. mitosis 2. differensiasi: induksi -interaksi 3. morphogenesis 4. organogenesis 3 Fertilization Pada waktu ovulasi sel ovum akan dikelilingi oleh corona radiata dan zona pelucida. Ovum yang sudah matur ditunjukkan dengan adanya 1 polar body. Spermatozoa bisa dari berbagai arah tetapi jika sudah ada yang masuk akan terjadi reaksi zona sehingga mencegah spermatozoa lain masuk. Masuknya spermatozoa ovum meiosis akan dilanjutkan dan menghasilkan pronuclei betina dan polosit kedua. Spermatozoa akan menjadi pronuclei jantan Kedua Pronuclei akan saling mendekat dan kromosom homolog berpasang- pasangan dan ini disebut syngamy. Dan dinamakan Zygote Lalu proses pembelahan mitosis pertama dimulai 4  Result of Fertilization 1. Restoration of diploid chromosome number 2. Species variation 3. Sex determination 4. Initiation of cleavage 5  Stages of development Early development is blastulation (the first week) Formation of the bilaminar embryo and implantation (the second week) Formation of the trilaminar embryo and morphogenetic (the third week) The embryonic period and organogenetic (the fourth to the eight week) The fetal period (the ninth week to birth) 6  The First Week Fertilization  Consist of the fusion of sperm and a ovum  This process occur as follows 1. The sperm passes through the corona radiata 2. The sperm penetrates the zona pellucida 3. The sperm head attaches to the surface of the ovum 7 4. The ovum reacts to sperm contact two ways a. Changes occur in the zona pelluzida and ovum’s cell membrane which prevent polysperm b. The oocyt continue second meiotic division process and expels the second polar body and the female pronucleus formation 5. Sperm loses its tail and its head enlarge to form the male pronuclei 6. The male and female pronuclei approach each other in the center of the ovum as a syngamy and then became Zygote 8  Early division of zygote into multiple cells Cleavage without increase in size, partitions contents Morula solid ball of cells Morula sel2nya masih totipotent sel bagian dalam sebagian apoptosis (membentuk rongga (Cyst) sebagian masih hidup disalah satu kutub (embryoblast) sel yang diluar menjadi Zygote lebih pipih (trophoblast) Blastocyst sehingga dinamakan blastula with blastocoele c Prosesnya: blastulasi 9  Implantation Steps (2th weeks) Three steps of implantation: 1. aposition is started when the Zona pelluzida degrading (hatching), 2. Adhesion, the pinopodes is important role in this process 3. Invasion , the erosive Syncytiotrophoblast invades the endometrial connective tissue and the blastocyst slowly embeds itself in endometrium. Second Week Minggu ke2: konseptus akan mengalami implantasi, terbentuknya cavum Amnion, chorion, mesoderma ekstraembryonicum, dan embryoblast menjadi 2 lapis (epiblast dan hypoblast) atau discus embryonicus. 11 The second week: implantation and chorion formation  Implantation: begins at the end at the first week and ends during the second week Implantation process as follow 1. Zona pellucida disappears (4-5) 2. Blastocyst attaches to endometrial epithelium (6) 3. Trophoblast erodes epithelium and endometrial stroma (7) 4. Trophoblast will be differed into cytotrophoblastic and syncytiotrophoblastic layer (7 to 8) 12 5. Lacunae appear in syncytiotrophoblast (8 to 9) 6. Blastocyst sinks beneath surface of endometrial epithelium (9-10) 7. Lacunar networks form (10 – 11) 8. Trophoblast invades endometrium sinusoid, and establish a uteroplacental circulation (11 to 12) 9. Endometrial epithelium completely re-forms over the implanted blastocyst (12 to 13) 10. Marked decidual reaction occurs in the endometrium (13-14) 13  The third week  Major changes occur as the bilaminar embryonic disc is converted into a trilaminar embryo composed of three primary germ layer  In the third week usually the first sign that a woman may be pregnant  Laboratory pregnant test depend on the presence of human chorionic gonadotropin (HCG), a hormone produced by trophoblast and excreted in the mother’s urine 15  The third week cont…… Primitive streak formation Notochord Formation Neural Tube Formation Somite Formation Coelom Formation Blood and Blood Vessel Formation Villi Formation 16 Perkembangan minggu ke-3 (jaringan embryo trilaminar) 17 Awal minggu Ke 3 CONCEPTUS Akhir minggu Ke 3 18 The Fourth To Seventh Weeks  The beginning of all major external and internal structures during this period  This critical period at development, if teratogen exposure this period will cause major congenital malformation  The three primary germ layers will be differentiated into various tissues and organs  The end at this period the main organ system have been established 19 1 2 3 1. Bentuk (utuh) dari luar 2. Potongan Bidang longitudinal 3. Potongan bidang transversal 20 weeks 21 weeks 22 weeks 23 24 Bentuk akhir tahap embryonal Panjang CR 25  UMUR 3 SAMPAI 8 MINGGU Selama periode embryo perubahan morphologi sangat besar 26 Jaringan embryonal 27 Differentiated process 28 Pada fase fetus perubahan terjadi terutama maturasi dari system organ dan proporsi bagian/organ tubuh  Reasonable estimates of the age of embryo/fetus can be determine from: 1. The day of onset of the last normal menstrual period 2. The estimated time of fertilization 3. Measurements of length (crown-rump (CRL) 4. External characteristics 30  AGE FOOT LENGTH FETAL WEIGHT (WEEKS) CR LENGTH (MM)* (MM)* (G)†9 50 7 8 10 61 9 14 12 87 14 45 Fetus development: 14 120 20 110 Maturation of the 16 140 27 200 tissues, organs and 18 160 33 3 20 increase of size so that 20 190 39 46 0 its optimize function 22 210 45 630 24 230 50 820 26 250 55 1000 28 270 59 1300 30 280 63 1700 32 300 68 2100 36 340 79 2900 38 360 93 3400 31 MAIN EXTERNAL CHARACTERISTICS (at weeks) Eyelids closing or closed (9) Early fingernail development. (10) Sex distinguishable externally. (12) Head erect (14) External ears stand out from head (16) Vernix caseosa covers skin (18) Head and body hair (lanugo) visible (20) Skin wrinkled, translucent, and pink to red (22). Fingernails present. Lean body (24) Eyelids partially open (26) Eyes wide open. Good head of hair often present (28) Toenails present (30). Fingernails reach fingertips (32) Body usually plump (36). Prominent chest; breasts protrude. Testes in scrotum (38) 32  Skema perkembangan konseptus dalam uterus Minggu ke-5 Minggu ke 10 Minggu ke-20 Minggu ke-40 Periode Kritis Perkembangan Embryo 34 Literature Moore K.L.,Persaud T.V.N. The Developing Human edisi ke-7. Saunder. USA 2003. 16-42 Carlson B.M.Patten’s Foundations of Embryology edisi ke-6.McGraw-Hill.New York.1996.121-143 35