A study on Oocyte and Oogenesis in viviparous fish Platypoecilus maculates

Platypoecilus macuhatus is a Viviparous fish belonging to subclass teleosteons (F. Poeciliidae). Oogenesis in this fish can be divided in tow following stage I: Clear Ooplasm with few organells is covered with a layer of follicular cells. Apearence of the first yolk droples also Occurred in this stage. Stage II: microvilli forms and then a radial layer appears between them. The development of Covering layers is due to the activity of both the oocyte a follicular cells. In addition the the peripheral vacuols appear in this Stage. StageIII: Differentiation and strengthening of covering layers. Continued and the follicular cells take columnar shape. Yolk storage of ooplasm also is increased. StageIV: in this stage ooplasm is with Yolk substance, the nuclear membrane is broken apart and as a result of oocyte growing, its membrane takes a smooth shape, and the mikrovilli length is decreased. Althoughin the process of oocyte development the desmosomes don’t exist after breading they appear in between the follicular cells. The fully grown oocyte is protected with four layers, where each layer play its specific role physiology and protectiveness.