The anatomy and development of the fidget mouse - With plates 2–4 and nine text-figure
The fidget gene causes abnormalities in the gross structure of the vestibular part of the membranous labyrinth. The horizontal semicircular canal and its crista ampullaris are both missing. The superior and posterior canals remain rudimentary in form, but the sense organs associated with them are normal.
The abnormalities of the membranous labyrinth lead to anomalies in the form of the osseous labyrinth and there is no subarcuate fossa.
The parafloccular lobes of the cerebellum are displaced into an abnormal position under the other lateral lobes.
The eyes and lens are reduced in size in fidgets, and the latter may remain in contact with the overlying ectoderm, which is probably a contributory cause of corneal ulcers.
The lachrymal glands are missing and there are marked corneal ulcers in adult mice.
In some fidget animals there is no mandibular canal.
The fidget gene increases the number of fusions between certain bones of the skull and in the tarsals.
In some fidgets there is a dislocation of the hip and in most fidgets the acetabulum is shallower than normal.
The fidget gene increases the incidence of polydactylism.
It is believed that the abnormalities of the membranous labyrinth are responsible for those of the osseous labyrinth and. still more indirectly, for the displacement of the paraflocculus. Similarly, the reduction of the lens is probably responsible for the reduction of the size of the eyes as a whole; and it is believed that the absence of the lachrymal glands (and with it the development of the corneal ulcers) is somehow connected with the rest of the eye anomalies. It is supposed that ear and eye anomalies may have a common cause the nature of which is, however, completely obscure. The physiological links of the statistical effects of the fidget gene with the more constant features of the syndrome remain to be discovered.
Volume 100, 2021
Continuous Article Publishing mode
Click here for Editorial Note on CAP Mode