Presentation on theme: "Classification Of Eggs Based Upon Amount Of Yolk"— Presentation transcript:
1 Classification Of Eggs Based Upon Amount Of Yolk Egg Type Representative Organismsa) Alecithal - Almost without yolk. Placental mammalsb) Microlecithal - Small amount of yolk. Echinoderms, amphioxus, marsupialsc) Mesolecithal - Moderate amount of yolk. Lung-fishes, frogs, and toads.d) Macrolecithal - Very large amounts of yolk. Sharks, bony fishes, reptiles, birds, insects.
2 Classification Of Eggs Based Upon Distribution Of Yolk a.) Isolecithal or Homolecithal - Yolk is evenly distributed. Occurs in the alecithal and microlecithal eggs of echinoderms, amphioxus, marsupials, and other mammals.b) Telotecithal - Yolk is concentrated on one end of the egg, the vegetal hemi-sphere, with the cytoplasm plus the nucleus concentrated the at other end, the animal hemisphere. Occurs in the mesolecithal and macrolecithal eggs of frogs, toads, birds, reptiles etc.c.) Centrolecithal - Yolk is in the center of the egg, with cytoplasm around it. Example: Insect eggs