Mainland, Donald

2019-02-15T14:34:54Z

2019-02-15T14:34:54Z

1927

A Historical Summary of the previous records of the pluriovular follicle is given,and it is pointed out that analysis reveals the lack of standardisation of these,and the consequent uncertainty of the actual frequency of the condition.

Various systematic examinations of 496 adult ferret ovaries have been made. The numerical results are set forth. Two separate groups of the ovaries were chosen at random,and sections were examined. In both groups,about one third of the ovaries showed the pluriovular condition.

The proportion of pluriovular follicles to the total number of follicles examined in a fairly large series was,very roughly, 0.1 per cent. When the smallest follicles were excluded,and the sections were examined serially,the percentage was about 1.5.

100 pluriovular follicles have been specially investigated,and the results are introduced into the discussion.

The growth and destiny of the pluriovular follicle are discussed. Conversion of true pluriovular follicles to uniovular is held to be rare. Degeneration of the ova and variations in the extent of growth of the various ova in a follicle are illustrated.

The species-distribution of the follicle is indicated,as far as possible. The opossum and the dog are noted as frequently exhibiting it. In Dasyurus,in the Texas armadillo, in man? and in at least certain varieties of pig, the condition appears rare.

(1) Plurinucleated ova. The ferret negatives the suggestion that there is a relationship to the pluriovular follicle. (2) Abundance of small follicles. No evidence is obtained from the ferret. (3) Tubular ingrowths of the germinal epithelium - notable in the dog;rare in the ferret.

The relationship of connective tissue to follicular cells is treated. (i) The possibility of secondary failure of the separating connective tissue at various stages of follicular development id discussed, and dismissed as improbable in the ferret ovary (2) The factors involved in the primary failure of the connective tissue to separate primordial follicles,are suggested. The pluriovular follicle in the ferret is attributed to this lack of balance between follicular and connective tissues.

The degree of the abnormality is considered. Biovular follicles were found to be the most common. The greatest deviation from the normal in this series was a small follicle with probably 14 ova.

The relationship of ova to epithelium in the pluriovular follicle is seen in many instances to lend support to the view of Foulis and Van Beneden,that the zona pellucida is formed by the ovum itself.

Pluriovular follicles are found more abundantly in the non-mature ferret in the mature. 39 young ferret ovartes have been examined for this purpose. The factors producing the condition are the same,qualitatively,as in the adult.

The growth and destiny of the pluriovular follicle are discussed. Conversion of true pluriovular follicles to uniovular is held to be rare. Degeneration of the ova and variations in the extent of growth of the various ova in a follicle are illustrated.

The relationship of the condition to fertility, in particular to "fecundity" (Pearl) is treated. Direct influer ce,by rupture of ari abnorma. 1 follicle,is cmnsidered rare. Two instances of rupture are recorded,in the ferret. Indirect relationship is dissussed in the light of possible types of evidence: (1.) Abundance of small follicles - doùbtful evidence of fecundity. (2.) Ovulation -rate (and litter- size). Pluriovular follicles may abundantly occur along with great fecundity(opossum);but they may occur\rrith -eat out great fecundity (dog)ami-laft43. Fecundity may be great and the follicular abnormality not common (Dasyurus and pig). In the ferret,fecundity is moderately high,and the follicular abnormality is not very frequent. The evidence fromsiñdividual instances is inadequate. The ferrpt ovaries which most abundant pluriovular follicles do not show a high ovulation -rate.

http://hdl.handle.net/1842/35120

The University of Edinburgh

Annexe Thesis Digitisation Project 2019 Block 22

The pluriovular follicle, with special reference to its occurrence in the ferret

The pluriovular follicle, with special reference to its occurrence in the ferret: written for the Gunning Victoria Jubilee Prize in Anatomy

Thesis or Dissertation

Doctoral

Prize Essay