Androtsey va mikrosporogenez

Androtsey va mikrosporogenez Androtsey haqida tushuncha haqida bilimga ega bo'ladilar. Mikrosporogenez va erkak gametofit haqida bilimga ega bo'ladilar. Reja: Guldagi changchilar to'plami androtsey deyiladi. Changchilar gulda bittadan bir necha yuztagachan bo'lishi mumkin. Changchilar - changchi ipidan va changdondan tashkil topgan. Chang- don ikki qismdan iborat bo'lib, bir-birlaridan bog'lagich orqali ajratilgan. Bog'lagich changchi ipining davomi bo'lib hisoblanadi. Har bir bo'lagi (teka) ikkita chang uyasidan tashkil topib, ichida mikrosporalar yetiladi. Chang ipi juda uzun va juda kalta bo'lishi mumkin. ANDROTSEY HAQIDA TUSHUNCHA Bargning shakil va strukturasidan ixsoslashgan gulning changchi va mevachi barglari keskin farq qiladi. Morfologik interpretaciya changchi va mevachi barglarning evolyutcion rivojlanishi xaqida hozir ham har hil fikrlar mavjud (Parkin, 1951). Bu organlar bargning gomologi degan umumiy qabul qilingan teoriya ham mavjud. Shunday fikrlar ham mavjudki changchini rivoshlanishini telom nazariyasi asosida tushuntirish mumkin yani primetiv dehotomik shoxlangan о'qtan changchi va urug'chi kelib chiqgan degan fikr.Bu nazariyaga asosan changchilar uchida sporangiy bо'lgan о'qning qisqarishi va tizimning birikishi hisobiga hosil bо'lgan (Wilson, 1937, 1942).Changchi va mevachi barglarning kelib chiqishi xaqida Beyli va uning hamkasiblari Ranales qobiliyasining kо'pgina oilalarida morfologik solishtirma anotomik izlanishlarining natijalarini nashr qildirgan. Shu izlanishdan malum bо'ldiki Ranalesning daraxt-simon turlari xozirda ksilemaning rivojlanishi nafaqat primetiv holatda saqlangan balki changchi va mevachi barglarning tiplari ham primitive holatda saqlangan (Beyli va Smith, 1942). The stamens and carpels of highly specialized flowers differ greatly in structure and general shape from foliage leaves. Different opinions still exist as to the morphological interpretation and evolutionary development of the stamens and carpels (Parkin 1951).The most commonly accepted theory is that these organs are homologous to leaves.The opinion also exists that the development of the stamen can be explained on the basis of the telome theory,that is from primitive dichotomously branched axes.According to this theory the stamen has developed as the result of the reduction and fusion of a system of axes that bore sporangia at their tips( Wilson,1937,1942) New light was thrown on the phylogeny of stamens and carpels by Bailey and his co-workers from their morphological and comparative anatomical research in many families of the Renales. From these imvestigations it has become apparent that in the woody species of the ranels that exist today not only primitive stages of xylem development have been preserved (Bailey and Smith,1942). A.Fahn.PlantAnatomy.NewYork.University.USA2011.19bob,430bet Androtsey va mikrosporogenez Mikrosporalar mikrosporaning ona hujayrasini meyoz bo'linishi natijasida paydo bo'ladi. Bu jarayon ikki tipda amalga oshadi: a) suksessiv tip - yadro avval ikkiga bo'linadi va hujayralar ...