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A. F. McFEE and J. J. KENNELLY

Summary.

A simple and convenient open-surgery procedure for testicular biopsy was tested on rabbits at 1, 3, 5 and 11 months of age. The technique yielded a representative sample of testicular material while damaging less than 1% of the remaining testicular tissue. At least two biopsies can be taken from the sufficiently separated areas of a testis at either 2- or 14-day intervals without the second sample being affected by the first.

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A. F. McFEE and M. W. BANNER

Summary.

All possible crosses were made between European wild pigs with either 36 or 37 chromosomes and domestic swine with 38. The 36×36 cross produced only pigs with 36; the 36×37 and 37×38 crosses yielded the parent numbers in about equal numbers of pigs. All pigs resulting from the 36×38 cross had 37, while crossing 37×37 gave progeny with 36, 37 or 38 in about a 1:2:1 ratio. It is surmised that the three unpaired members in the 37-chromosome animal act as a trivalent during meiosis with two telocentric chromosomes behaving as a unit. No firm evidence indicated reduced fertility in any of the animals nor were any physical changes evident which could be associated with different chromosome forms.

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A. F. McFEE, J. R. EBLEN and P. R. WELCH

In order to study the effect of irradiation on testicular function it is important to know the frequency with which ejaculates must be taken to establish accurately the post-irradiation pattern of sperm output. The interval from irradiation to the onset of sterility in mice is said to be unaffected by varying the frequency of mating (Bateman, 1958). 32Phosphorus-labelled spermatozoa appear in the ejaculate of bulls at approximately the same time whether they are collected two to three times a day or once a week (Koefoed-Johnsen, 1960). On the other hand, Cox & Willham (1961) found that irradiated boars reached their minimum sperm output some 12 days later when collected once a week than when collected three times a week, although the pattern of recovery in sperm production was not altered.

The

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W. C. D. HARE, R. A. McFEELY and D. F. KELLY

Abnormal mammalian gonadal and, consequently, genital differentiation usually occurs with heteroploidy and other abnormalities of the sex chromosomes, but can also occur when the sex chromosome constitution appears to be normal.

One expression of the latter situation is in cases of male pseudohermaphroditism with two X, but apparently no Y, sex chromosomes. There have been several reports of this in man (see de la Chapelle, 1972), pig (see Breeuwsma, 1970), goat (see Hamerton, Dickson, Pollard, Grieves & Short, 1969) and horse (Bornstein, 1967; Generke & Coubrough, 1970), but only one in the dog (Edols & Allan, 1968). This paper describes three more cases in closely related dogs with similar anatomical abnormalities.

The propositi were three English cocker spaniels, two (A and B) were littermates, and the third (C) was a sib (Text-fig. 1). They were