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Biomedical subjects

S E Long

Publications and source records attributed to S E Long.

At least 73 records · Page 4Linked to original sources
PubMed1980

Some pathological conditions of the reproductive tract of the ewe.

The reproductive tracts of 276 ewes from six breeds or crosses were examined. The incidence of pathological conditions was 8.7 per cent. The largest group of abnormalities was extensive abdominal adhesions. The first case of ovarian cystadenoma in sheep is reported.

Animals↗
PubMed1980

An examination of chromosomes in the stallion (Equus caballus) during meiosis.

Meiotic preparations were made from testicular material obtained after surgical castration of eight stallions (Equus caballus) with normal spermatogenesis. The material was examined after conventional Giemsa staining and C-banding. C-banding demonstrated that the Y chromosome at diakinesis associated with the short arm of the X chromosome. In 315 cells at diplotene or diakinesis, 56 (17.7%) had univalents and 51 (16.1%) of these involved the sex chromosomes. The overall mean chiasma number was 54.4 +/- 1.8 SD, and the mean calculated nondisjunction (ND) frequency was 3.4%. These results are discussed in relation to other domestic species.

Animals↗
PubMed1980

Frequency of chromosomal abnormalities in early embryos of the domestic sheep (Ovis aries).

Embryos or unfertilized eggs were collected 2 or 3 days post coitum from mature sheep of various breeds and crosses. The karyotypes of 89 of the 376 collected were established. There were 44 embryos with 2n = 54XX, 30 with 2n = 54XY;1 was a 2n/1n mouse; 4 had 2n + 1 chromosomes giving an incidence of trisomy of 4.7%; and 1 unfertilized egg had n = 28. The incidence of chromosomal abnormalities was 6%, and 1.3% of the eggs or embryos had a cracked zona pellucida.

Animals↗
PubMed1979

The fertility of bulls born twin to freemartins: a review.

Evidence for the existence of XX germ cells in the testes of bulls born twin to females is reviewed. It is concluded that there is probably no shift in the sex ratio of the offspring in favour of females. Reports on the fertility of such bulls are reviewed. It is suggested that, provided the semen is normal, there is no reason why such a bull should not be used for breeding purposes.

Animals↗
PubMed1978

Reproductive performance of ewes mated to rams heterozygous for the Massey I (t1) centric fusion (Robertsonian) translocation.

One hundred Scottish Blackface ewes were mated to New Zealand Romney rams heterozygous for the Massey I (t1) centric fusion (Robertsonian) translocation. The lambing percentage of ewes lambed was 131 and the segregation of normal to balanced heterozygous lambs was 1:1. No chromosomally unbalanced lambs were born. Nine heterozygous females were mated to a heterozygous male and produced two homozygous, three heterozygous and seven normal lambs. The homozygous male had hypoplastic testes. The results indicate that there is no significant reduced fertility with 53XYt1 rams but that fertility of 52XYt1t1 rams should be further investigated.

Animals↗
PubMed1978

Chiasma counts and non-disjunction frequencies in a normal ram and in rams carrying the Massey I (t1) Robertsonian translocation.

Testicular material from a normal ram (54XY), three rams heterozygous (53XYt1) and one ram homozygous (52XYt1t1) for the Massey I (t1) translocation was examined. The autosomal non-disjunction in the normal ram was 2.0% compared to a mean of 6.1% in the heterozygous animals. In the homozygous animal there were adhesions of the tunica vaginalis to the cauda epididymidis and extensive spermatogenic arrest.

Animals↗
PubMed1977

Cytogenetic examination of pre-implantation blastocysts of ewes mated to rams heterozygous for the Massey I (t1) translocation.

One hundred-and-two 13- to 18-day blastocysts were collected from 98 Scottish Blackface ewes mated to one of four New Zealand Romney rams heterozygous for the Massey I (t1) translocation. The karyotype of 75 blastocysts was established, of which 22 were 54,XY, 18 were 54,XX, 20 were 53,XY,t1, and 15 were 53,XX,t1. It is suggested that these results indicated that there was no increase in embryonic loss in ewes mated to rams heterozygous for the Massey I (t1) translocation and that the unbalanced secondary spermatocytes in heterozygous males probably did not mature to spermatozoa.

Animals↗