what is the easiest way to distinguish/predict an organism has protonephric, mesonephric or metanephric kidneys and also what is the difference between all three?
The various stages of kidney development can be distinguished by:
The pronephros develops in the cervical region of the embryo.
The mesonephric duct extends towards the most caudal end of the embryo.
The metanephric duct grows posteriorly and towards the head of the embryo.
The difference between them is:
- Pronephros is the earliest nephric stage in humans and constitutes the mature kidney in most primitive vertebrates and it disappears completely by the 4th week of human embryonic life.
- Mesonephros is the principal excretory organ during early embryonic life and gradually degenerates and f become a part with male reproductive organ.
- Metanephros is the permanent and functional kidney in higher vertebrates.