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Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
This phenomenon is an automatic-response mechanism that activates even before a human becomes consciously aware that a startling, unexpected or unknown sound has been "heard". [2] That this vestigial response occurs even before becoming consciously aware of a startling noise would explain why the function of ear-perking had evolved in animals.
Humans may have physical remnants of a VNO, but it is vestigial and non-functional. [ 2 ] The VNO contains the cell bodies of sensory neurons which have receptors that detect specific non-volatile (liquid) organic compounds which are conveyed to them from the environment.
In females, the mesonephros degenerates entirely, though vestigial structures such as Gartner's ducts, the epoophoron, and paroophoron are common. In males, a few of the more caudal tubules will survive and give rise to the efferent ductules of the testis , [ 1 ] the epididymis , vas deferens , seminal vesicle , as well as vestigial structures ...
Vestigial-like family member 3 is a protein that in humans is encoded by the VGLL3 gene. [ 5 ] This protein is one of four mammalian homologs (VGLL1-4) of the vestigial gene found in the fruit fly Drosophila . [ 6 ]
Atavism can also be seen in humans who possess large teeth, like those of other primates. [9] In addition, a case of "snake heart", the presence of "coronary circulation and myocardial architecture [that closely] resemble those of the reptilian heart", has also been reported in medical literature. [ 10 ]
The term spur is sometimes used to describe the pelvic spur, vestigial limbs found in primitive snakes, such as boas and pythons and in the striped legless lizard. [3] [4] The spurs primarily serve as holdfasts during mating. As these form at the terminal end of the limb, they may properly be claws rather than true spurs.