[Medical Q&A] Does the incomplete "tadpole" still have any functions?

Planner: Chinese Medical Association

Reviewer: Zhuang Jintao, deputy chief physician, First Affiliated Hospital of Sun Yat-sen University

When it comes to "tadpoles", many people will think of "sperm" because the two are very similar in shape. If we look at it from a more microscopic level, the normal morphology of sperm can be roughly divided into the head and the tail, and the tail is divided into the middle neck and the main segment.

The head of the sperm should be smooth and generally oval, with a very clear acrosome covering most of the head (the acrosome accounts for 40% to 70% of the head and is the key part responsible for combining with the egg). Head defects can be manifested as large heads, small heads, conical heads, round heads, amorphous heads, double heads, acrosomes that are too large or too small, etc. This part of the abnormality will affect the ability of the sperm to penetrate the egg. The neck and middle section of the sperm should be slender and regular, similar to the length of the head. The main axis of the middle section of the neck is in a straight line with the head. If there is a defect in this part, it can be manifested as a curved neck, a middle section that is too thick or too thin, etc., which will affect the motility of the sperm. The main section of the sperm is thinner than the middle section, and the thickness is more uniform. The length is about 10 times that of the head. The defects of the main section are mainly manifested as short tails, multiple tails, broken tails, irregular tail width, curled tails, etc. This part of the abnormality will also affect the motility of the sperm. A sperm may have multiple types of abnormalities, such as both head defects and tail defects. The function of such sperm will be more seriously damaged, thus seriously affecting the success rate of fertilization and the quality of the embryo. Of course, with the help of modern assisted reproductive technology, "tadpoles" with certain types of defects still have a chance to combine with eggs, or in other words, such couples still have the opportunity to have their own children.