Seven novelKITmutations in horses with white coat colour phenotypes

Ovaries can be used in place of gametes as a resource for cryopreservation. Thus far, we have shown that in the Syrian hamster, pups can be successfully produced through the transplantation of fresh and cryopreserved ovaries. In this study, we attempted to simplify the ovarian cryopreservation procedures to facilitate the easy application of these techniques. In particular, the procedure would be easier and quicker if the ovaries did not have to be cut into small pieces before ovarian cryopreservation. Therefore, we examined the effects of ovarian fragment size on subsequent offspring production. Ovaries were cryopreserved by vitrification according to methods described for mouse ovaries (Migishima et al. 2003 Biol. Reprod. 68, 881–887). In brief, ovaries were collected from 3-week-old J2N-n strain (white coat) females. Because we had previously confirmed that quarter-sized ovaries could be used for cryopreservation, intact (∼3.5 × 2 mm) and half-sliced ovaries (∼2 × 1.5 mm) were cryopreserved by vitrification using DAP213 solution (2 M dimethyl sulfoxide, 1 M acetamide, and 3 M propylene glycol; Nakagata 1989 J. Reprod. Fertil. 87, 479–483). Thawed ovaries were transferred into the ovarian bursae (single intact ovary or two half-sliced ovarian pieces per ovarian bursa) of 3-week-old recipient females with agouti-coat (Slc:Syrian) under isoflurane anaesthesia. Not all of the recipients’ ovaries were removed immediately before transfer; both the donor’s and a small portion of the recipient’s ovaries were present in each ovarian bursa. Successful ovarian transplantation was verified by examining the coat colour (non-agouti colour) of offspring produced in test matings between mature recipients and J2N-n males. Of the 3 and 6 recipients that received intact and sliced ovaries, respectively, 2 and 5 recipients delivered pups. Based on the coat colour of the pups, 1 of the 5 recipients delivered a pup produced from transplanted half-sliced ovaries. Our results indicate that half-sliced-size ovaries (smaller than a 2-mm cube) can be successfully used for cryopreservation in the Syrian hamster. Specifically, it is not required to slice the ovary into smaller pieces. This work was supported by a grant from the Ministry of Health, Labour and Welfare, Japan and Grant-in-Aid for Scientific Research (C).

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Observations on the histological features, development and pathogenesis of the inner ear degeneration of the deaf white cat

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1965.0030 ◽

1965 ◽

Vol 162 (987) ◽

pp. 147-170 ◽

Cited By ~ 69

Keyword(s):

Inner Ear ◽

System Analysis ◽

Stria Vascularis ◽

Dominant Gene ◽

Coat Colour ◽

White Coat ◽

Histological Features ◽

Progressive Degeneration ◽

Points Of Interest ◽

Genetically Determined

The histological features, development and pathogenesis of the inner ear degeneration in the deaf white cat has been studied in 57 kittens bred from 4 female and 2 male parent animals. The degeneration makes its appearance between the 4th and 6th day of post-natal life, and up to this time no histological abnormalities can be recognized in the inner ear. The degeneration is confined to the cochlea and saccule. In the cochlea a progressive degeneration of Corti’s organ is seen and appears to be associated with volume oscillations of the endolymph. A trophy of the stria vascularis also occurs. The saccule collapses but its fluid connexions with the endolymphatic duct remain patent. No significant changes are seen in other parts of the inner ear, including the saccus endolymphaticus and the vestibular system. Analysis of the genetic data shows that the white coat colour and inner ear degeneration are due to the effect of a single dominant gene, the penetrance for the white coat colour being complete and that for the inner ear degeneration, 80 %. Points of interest are that in a small number of white animals inner ear degeneration is unilateral in some and absent altogether in others. It is thought that the inner ear degeneration is essentially a derangement of the water electrolyte regulating mechanism of the inner ear. In this the gene is thought to play a part by reducing the enzyme content of the developing organ in its critical maturation phase and is supplemented in this action by certain unfavourable environmental factors. Similar mechanisms are thought to be involved in the pathogenesis of the inner ear degeneration which is commonly present in cases of human congenital deafness, not only when this is genetically determined but also in a certain important group of individuals in whom genetic factors appear to be absent.

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