During development, the human fetus produces a tail which disappears a few weeks later. But this can persist until birth in extremely rare cases. As is the case for this baby born in Brazil at the beginning of 2021.
It is a vestige that comes to us from our distant ancestors. During human development, a tail appears between the fourth and sixth weeks of gestationgestation. It disappears at the end of the eighth week, eliminated by macrophages. But in extremely rare cases, this vestigial structure persists until birth! Earlier this year, a baby was born in Brazil with a 12-centimeter real tail in the lumbosacral region. The doctors of Albert Sabin Children’s Hospital in Fortaleza, in the east of the country, share this clinical case in a publication by Journal of Pediatric Surgery Case Reports.
Rare case of a true tail in a baby
When we talk about tails in humans, we should not expect to see a tail that resembles that of other animals but without hair. The newborn in question here, a boy born at 35 weeks amenorrhea, had a rope fibrousfibrous about twelve centimeters which ended in a ball four centimeters in diameter above his left buttock. No other anomalies were identified. Doctors surgically excised the tail. The successful intervention was an opportunity to analyze it more closely.
The appendix is composed of skin, fatty tissue, nervesnerves as well as blood vessels, but without bones or cartilagecartilage. This is the definition of a true tail, which is different from a much more common pseudo-tail. Without bones, it is soft, but capable of motor reflexes and spontaneous contractions.
The pseudo-tails appear similar at first glance but their tissue organization differs, they contain only adipose and cartilaginous tissues. They are also located in the lumbosacral region and linked to the coccyxcoccyx. Pseudo-tails are often associated with other lesions (lipoma, teratomateratoma) or anomalies of the spinespine.
The pathophysiology of human tails is not completely understood as they are rare, but a dysjunction of the neural tube could perhaps prevent the development and then the normal disappearance of the tail during the development of theembryoembryo.
