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M H Thorne

Publications and source records attributed to M H Thorne.

13 recordsLinked to original sources
PubMed1999

Hydronephrosis and ureteral duplication in a young alpaca.

A seven-month-old male alpaca (Lama pacos) with signs of abdominal straining was examined. A fluid-filled structure was palpable in the mid-abdominal region, and ultrasonography revealed a hydronephrosis of the right kidney, with an associated mega-ureter. The affected kidney was removed and the clinical signs resolved. Histological examination of the kidney revealed the unusual congenital abnormality of ureteral duplication. It is suggested that the hydronephrosis developed as a result of this underlying condition.

Animals↗
PubMed1995

Development of the gonads in the triploid (ZZW and ZZZ) fowl, Gallus domesticus, and comparison with normal diploid males (ZZ) and females (ZW).

Gonadal development in fowls aged from 1 day to more than 4.5 years was studied in 63 ZZW and 16 ZZZ triploid crossbreds and compared with normal diploid males (ZZ) and females (ZW). In the ZZW fowl, the right gonad developed into a testis (although this occurred earlier in the ZZ genotype), and a structurally-abnormal excurrent duct system containing some malformed spermatids and spermatozoa was associated with the gonad of young adults. The left gonad was an ovotestes at hatching and no excurrent ducts were associated with it. The ovarian component was much less developed than that in the ZW genotype-it started to degenerate by 1 week of age, and most of the oocytes had disappeared by about 3 weeks of age. The seminiferous tubules developed in the medullary region, but only abnormal spermatozoa were produced. Leukocytes infiltrated both gonads at about 9 months of age and the seminiferous epithelium had degenerated in most fowls over 1 year old. In ZZZ fowl, gonadal and excurrent duct development was normal, but occurred earlier than in the ZZ genotype. However, meiosis and spermiogenesis were abnormal and malformed spermatozoa were produced. The heads of spermatozoa from the ducts deferens were about 1.4-times longer in the ZZZ genotype than in the ZZ genotype, indicating that the former may be producing some diploid spermatozoa.

Animals↗
PubMed1995

Electron microscopy of the seminiferous epithelium in the triploid (ZZZ and ZZW) fowl, Gallus domesticus.

The ultrastructure of cells of the seminiferous epithelium is described in both triploid ZZZ and ZZW fowls, especially cytological aberrations influencing the development of morphologically abnormal spermatids and spermatozoa. Mitotic divisions in triploid fowls are similar to those in diploid fowls, but meiosis in both the ZZZ and ZZW triploid fowl is abnormal and many defective gametes are produced. The majority of spermatids have structural abnormalities and this is attributed to the aneuploidy expected from meiotic chromosome pairing in a triploid. Some spermatids were observed to possess an irregularly shaped head, 2 centriolar complexes, 2 acrosomes and 2 tails and this type differentiated into large-headed spermatoza. Such spermatids and spermatozoa are suggested to be near diploid due to their large nuclear size and 2 sets of organelles. Other spermatids, observed with only 1 centriolar complex, 1 acrosome and 1 tail, are suggested to be near haploid. Differentiation of these spermatids is similar to the process observed in diploid fowls except that there is a high percentage of abnormally shaped heads. The fact that morphologically normal spermatozoa were rare is consistent with the expectation that very few spermatozoa would be exactly haploid. In both ZZZ and ZZW triploid fowls, triple pairing of chromosomes is observed in synaptonemal complexes (SC) during meiosis and recombination nodules are distributed at random in the central regions of the triple pairing SC. In ZZW triploid fowls gamete formation is more severely affected than in ZZZ triploid fowls and it is suggested that many of the degenerative changes occurring in ZZW fowls could be attributed to those spermatids that possess a W sex chromosome, since normal male fowls are the homogametic sex (ZZ) and normal spermatids and spermatozoa contain only a Z sex chromosome.

Animals↗
PubMed1991

Chromosome analysis of early embryonic mortality in layer and broiler chickens.

1. Twenty-three lines of chickens, obtained from grandparent stocks of 4 Australian breeding companies, were analysed to determine the incidence of early embryonic mortality attributable to chromosome abnormalities. The lines included 10 layer strains, consisting of 6 White Leghorn, 2 New Hampshire and 2 Australorp lines, and 13 broiler lines. 2. A total of 10,730 eggs was examined after 3 d incubation; of these 9746 (90.8%) were fertile. Abortive embryonic development was observed in 1379 (14.1%) of the fertile eggs. This consisted of 952 (69.0%) dead and dying embryos, including 646 malformed and 427 (31.0%) membranes without embryos. 3. Early embryonic mortality was found to vary from 9.8 to 26.8% (average 16.4%) in broiler lines and from 8.0 to 27.9% (average 11.9%) in layer lines. 4. Among 898 abortive embryos analysed, 112 had abnormal chromosomes consisting of 27 haploids, 38 haploid-euploids, 24 triploids, 16 diploid-polyploids, 4 aneuploids, 2 tetraploids and 1 translocation. 5. In broilers and layers respectively, chromosome abnormalities were responsible for 4.4 to 28.1% (average 11.8%) and 7.4 to 25.0% (average 13.4%) of the early embryonic mortality. 6. The overall frequency of chromosome abnormalities in all fertile eggs varied from 0.7 to 3.7% for the broiler lines and 0.7 to 3.4% for the layer lines.

Animals↗
PubMed1991

Cytological evidence of maternal meiotic errors in a line of chickens with a high incidence of triploidy.

Direct evidence of the nature of maternal meiotic errors in a selected line of chickens with a high incidence of triploidy was obtained by using cytologically marked paternal gametes derived from a closely related avian species. Matings were made by artificial insemination of female chickens of the selection line and a control line with semen from ring-necked male pheasants. A total of five triploid, one pentaploid, and 21 diploid hybrid embryos were karyotyped. Each triploid hybrid embryo contained one set of paternal pheasant chromosomes and two sets of maternal chicken chromosomes, providing irrefutable cytological evidence that the triploids were derived from diploid ova produced by females of the selection line. The pentaploid hybrid contained one set of paternal pheasant chromosomes and four sets of maternal chicken chromosomes, indicating that it had been derived from a tetraploid ovum. Females of the selection line are thought to have a genetically mediated susceptibility to nondisjunction which is responsible for the high incidence of meiotic errors. Evidence is provided that the non-disjunction occurs at both meiosis I and meiosis II.

Animals↗
PubMed1987

Live haploid-diploid and other unusual mosaic chickens (Gallus domesticus).

Sixteen haploid-diploid chickens, four diploid-triploids, and one haploid-diploid-triploid chicken have been found in a layer line of crossbred origin. Live haploid-euploid vertebrates have not been reported previously. Flow cytometric analysis revealed 1-80% haploid red blood cells (RBCs) in the haploid-euploid chickens and 5-30% triploid RBCs in the diploid-triploids. Mosaic cell lines were also found in leukocytes and many tissues. The haploid-diploid chickens were all phenotypically normal and fertile, but the phenotype and fertility of the diploid-triploid chickens depended on their sex-chromosome complements and the ratio of diploid to triploid cells. The haploid cell lines are thought to originate from supernumerary spermatozoa, and the diploid-triploids from binucleated oocytes with meiotic errors. It is likely that genetic factors are partly responsible for the occurrence of these mosaic chickens.

Animals↗
PubMedDate not supplied

Genetic analysis of triploidy in a selected line of chickens.

We investigated the pattern of inheritance of maternal meiotic errors responsible for a high frequency of triploid progeny in a selected line of chickens. For the genetic analysis, F1 and backcross populations were produced from crosses between normal diploid individuals of the triploidy line and a control line. Triploid embryos were produced by 35% and 67% of reciprocal F1 females and by 24% and 67% of reciprocal backcross females. These results exclude autosomal recessive and sex-linked recessive or sex-linked dominant inheritance. A single autosomal dominant gene is also not likely to be responsible. However, the results are consistent with the determination of triploidy by a single autosomal gene with no dominance, and an even better fit is obtained by two loci, an autosomal gene with no dominance and a sex-linked gene. The results cannot exclude a multifactorial mode of inheritance, but the rapid response to selection for triploidy and consistent expression of the meiotic errors in different genotypes suggest that meiotic mutations at one or two loci are the most plausible genetic basis for the trait.

Animals↗
PubMedDate not supplied

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