Spermatogenesis dan oogenesis
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Gametogenesis is the process of forming gametes or mature spores. In animals, gametogenesis involves the formation of sperm cells (spermatogenesis) in the testes or egg cells (oogenesis) in the ovaries through cell growth and differentiation after meiosis. Spermatogenesis involves primordial cells undergoing mitosis and meiosis to form spermatids that develop into sperm cells. Oogenesis involves oogonia undergoing mitosis and meiosis to form oocytes, though initial steps occur prior to birth resulting in fewer mature egg cells compared to the number of original primordial cells.
Spermatogenesis dan oogenesis
- 2. Gametogenesis ï‚—Gamet-gamet sebagai produk akhir meiosis sesungguhnya belum sepenuhnya berkembang. ï‚—Dibutuhkan suatu periode pematangan setelah meiosis sampai menjadi gamet yang siap berfungsi dalam fertilisasi. ï‚—Pada tumbuhan, satu atau lebih pembelahan mitosis diperlukan untuk menghasilkan spora-spora yang reproduktif (Mikrospora dan megaspora). ï‚—Sedangkan pada hewan, melalui pertumbuhan dan/atau diferensiasi produk-produk meiosis langsung berkembang menjadi gamet. ï‚—Proses penghasilan gamet-gamet atau spora-spora matang/dewasadisebut gametogenesis.
- 3. ï‚—Gametogenesis pada hewan jantan disebut spermatogenesis, yaitu terbentuknya sel sperma atau spermazoan (n) dari spermatogonium di dalam gonad jantan (testis).
- 4. SPERMATOGENESIS ï‚—Prosespembentukanspermadalamtestis ï‚—Sel-selprimordialdiploiddidalamtestismembelahberkali-kalisecaramitosismembentukspermatogonium ï‚—Spermatogoniummengalami/diferensiasipertumbuhanmembentukselspermatositprimer(2n) ï‚—Meiosisof each spermatocyte produces 4 haploidspermatids. This process takes over three weeks to complete.
- 5. ï‚—Gambar 1.11. Gametogenesis pada hewan (Sumber: Klug, dkk., 2007 hal. 22)
- 7. Sperm ï‚—Sperm cells are little more than flagellated nuclei. Each consists of : ï‚—a head, which has ï‚—an acrosomeat its tip and ï‚—contains a haploid set of chromosomes in a compact, inactive, state. ï‚—a midpiececontaining mitochondriaand a single centriole ï‚—a tail
- 10. OOGENESIS ï‚—Gametogenesispadahewanbetinadisebutoogenesis, yaituterbentuknyaselteluratauovum(n)darioogoniumdidalamgonadbetina(ovarium). ï‚—(Prosespembentukanseltelurdidalamovarium) ï‚—Sel-selpadaovariummembelahberkali-kalisecaramitosismembentukoogonium ï‚—Oogoniummengalamipertumbuhanmembentukseloositprimer(2n)
- 11. Sex Organs of the Human Female
- 13. Oogenesis In contrast to males, the initial steps in egg production occur prior to birth. Diploid stem cells called oogoniadivide by mitosis to produce more oogoniaand primary oocytes. By the time the fetus is 20 weeks old, the process reaches its peak and all the oocytesthat she will ever possess (~4 million of them) have been formed. By the time she is born, 1–2 million of these remain. Each has begun the first steps of the first meiotic division (meiosis I) and then stopped. No further development occurs until years later when the girl becomes sexually mature. Then the primary oocytesrecommence their development, usually one at a time and once a month.
- 15. STRUCTURE AND FUNCTION OF THE EGG ï‚—During oogenesis, the cytoplasm is unevenly divided during each meiotic division.This results in one egg and three polar bodies. ï‚—Here is why.Egg cells must contain enough supplies to synthesize all the products needed by the developing embryo until the embryo implants into the uterine wall.Implantation does not occur until 7-10 days after fertilization.Thus, the unequal division of the cytoplasm ensures the egg has enough supplies for this time period.
- 19. A damaged cell may undergo apoptosis if it is unable to repair genetic errors. Apoptosis is a common process throughout life that helps the body get rid of cells it doesn’t need Control of cell growth and division
- 20. Control of cell growth and division When a cell undergoes apoptosis, white blood cells called macrophages consume cell debris.
- 21. Kanker ï‚—Kankerpembunuhterbesar, yaitukankerparu- paru, membunuhhampir90% penderitanya, atauhampir30% dariseluruhkematianakibatkanker. Namunsesungguhnyajustrukankerparu-parulahyang paling mudahdicegah. Survey dalambeberapadekademenunjukkanbahwasatu-satunyapenyebabmayoritaskankerparu-paruadalahasaprokok.
- 23. Gambar Penyakit Kanker (1) Tampak Depan(Ca. mamma) Tampak Samping Ca. ma di Axillary Tail Spencer Contoh Kanker Payudara
- 24. ï‚—Karsinogen ï‚—Zat-zat karsinogen (pemicu kanker) yang terkandung pada rokok adalah: ï‚—vinyl chloride ï‚—benzo (a) pyrenes ï‚—nitroso-nor-nicotine ï‚—Satu-satunya zat yang lebih berbahaya daripada asap rokok dalam memicu kanker paru-paru adalah zat-zat radioaktif. Itu pun jika dimakan atau dihisap dalam kadar yang cukup.
- 25. Efek Kanker Paru-Paru Gambar di bawah menunjukkan paru-paru yang dirusak oleh kanker. Gambar di kanan (diperbesar) menunjukkan alveoli yang terkena kanker.
- 26. http://www.accessexcellence.org/AE/AEPC/NIH/gene13.html Cancer usually arises in a single cell All cancer is genetic
- 27. ï‚—Genetic mutation and cancer development ï‚—Cancer results when cells accumulate genetic errors and multiply without control ï‚—Cancer results from a disruption of the normal regulation of the cell cycle. ï‚—When the cycle proceeds without control, cells can divide without order and accumulate genetic defects that can lead to a cancerous tumor
- 28. Cancer results when cells accumulate genetic errors and multiply without control.
- 29. ï‚—Oncogenesnormally encourage cell growth; when mutated or overexpressed, they can flood cells with signals to keep on dividing. ï‚—Tumor-suppressor genesnormally restrain cell growth; when missing or inactivated by a mutation, they allow cells to grow and divide uncontrollably