I.Types of egg on the basis of amount of yolk1. Name of Egg: Alecithal
Amount of Yolk: Negligible of yolk
Example: Human and other mammals (Placental mammals)
2. Name of Egg: Microlecithal
Amount of Yolk: Small amount of yolk.
Example: Echinoderms(Sea urchin), Branchiostoma, Amphioxus, Marsupials
3. Name of Egg: Mesolecithal
Amount of Yolk: Moderate amount of yolk.
Example: Lung-fishes, Amphibians (frogs and toads)
4. Name of Egg: Macrolecithal or Megalecithal or Polylecithal
Amount of Yolk: Large amounts of yolk.
Example:Sharks, Bony fishes, reptiles and birds
II. According to the distribution of Yolk
1. Name of Egg: Iso lecithal or homolecithal
Distribution of Yolk: Yolk is evenly distributed.
Examples: Occurs in alecithal and microlecithal eggs. Sea urchin, amphioxus,marsupials,other mammals2. Name of Egg: Centrolecithal
Distribution of Yolk : Yolk at the centre of egg, with cytoplasm around it.
3. Name of Egg: Telotecithal
Distribution of Yolk :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.
Examples: Occurs in the mesolecithal and macrolecithal eggs of frogs, toads, birds, reptiles etc.