baca biology smpai muntah. itu sebab aku bce last minit. ngehngeh. inilah yg dinamakan just in time (JIT). budak2 after SPM yg nak teruskan pengajian jangan lah jadi macam aku. mau tak berdarah otak. ye le, otak kita ni bukan mcm otak budak-budak pandai ( sedih ) lalalala~~ aku hafal, mls nk ttulis balik dlm paper, so aku tulis le kat sini as revision di samping mendedahkan ilmu pengetahun kpd org ramai. (sebenarnye nak jimat paper) huahahaha
spermatogenesis (in seminepherous tubule)
primordial germ cell undergoes differentiation to produce spermatogonium. spermatogonium undergoes mitosis to form two daughter cell. one remains as spermatogonium. the other one will undergoes differentiation and onset meiosis 1 to form primary spermatocyte. primary spermatocyte complete meiosis 1 to produce secondary spermatocyte. this secondory spermatocyte undergoes meiosis 2 to produce early spermatids. the spermatids undergoes differentiation to form sperm cell (spermatozoa)
role hormone in spermatogenesis
at puberty, hypothalamus secrete ganadotrophin releasing hormone (GnRH) to stimulate anterior pitiutary gland (AP Gland). AP Gland secrete Follicle Stimulating Hormone (FSH) and Leutinizing Hormone (LH). AP Gland secrete LH to stimulate Leydig Cell to produce testosterone. testosterone stimulate the development of sperm to produce spermatogenesis
AP Gland secrete FSH to stimulate Sertoli Cell. this Sertoli Cell will give nourishment/nutrient to spermatogenesis and secrete inhibin.
when testosterone is higher, it will act on Hypothalamus and AP Gland by negative feedback. it will inhibit the secretion of GnRH. so, AP Gland cannot produce FSH and LH.
when sperm count is higher, inhibin will act on AP Gland by negative feedback. AP Gland reduce the secretion of FSH and LH.
*function of testosterone : along with FSH to stimulate spermatogenesis
develop and maintain the secondary characteristics
stimulate sexual urge
oogenesis (in ovary)
before birth : primordial germ cell undergoes mitosis to form diploid oogonium. oogonium growth in size to produce pimary oocyte. primary ooctyte undergoes meiosis 1 but suspended at phropase 1. so, ovary inactive.
during childhood : primary oocyte complete meiosis 1 producing first polar body and big secondary oocyte. the secondary oocyte undergoes meiosis 2 but arrested at metaphase 2.
secondary oocyte complete meiosis 2 only after penetrate with sperm (during ovulation). thus, it will produce haploid second polar body and haploid ovum.
hormone control in oogenesis
hypothalamus secrete GnRH to stimulate AP Gland. AP Gland secrete FSH and LH.
FSH cause development of follicle
FSH cause cell developing and produce oestrogen. oestrogen will stimulate the thickening of endometrium wall.
oestrogen increase sharply so it will act on AP Gland to produce FSH and more LH.
AP Gland secrete LH and cause ovulation and empty follicle to transform to corpus luteum. the corpus luteum will produce progestrone. progestrone will further thickening and vascularisation endometrium in preparation of implantation.
after ovulation, the level of oestrogen and progestrone will increase and then decrease. when the level progestrone is higher after ovulation, it will act on hypothalamus and AP Gland to inhibit the secretion of LH. so, the level LH is decrease, corpus luteum disintegrate, level progestrone and oestrogen decrease, endometrium wall disappears and menstrual cycle start.
|mummy daddy kakky abby, help me|
p/s : ini baru sikit derr. aku rasa nak tulis lagi tp nnti panjang le pula entri blog aku.aduhai biol, juling sudah mata aku tengok kau. ni kalau tak keluar pekse nnti, mmg aku ketuk ketuk perut lembaga tu tauuu. mampukah aku mengingati semua? wish me luck on tuesday nieee yee :@