Histoenzymologic evaluation of metabolic patterns in bovine follicular oocytes
Kenney, R.M.
American Journal of Veterinary Research 34(7): 893-896
1973
ISSN/ISBN: 0002-9645 PMID: 4737192 Document Number: 69765
The reproductive tracts of 14 virgin heifers were removed from the stunned animal at various points in the oestrous cycle, and ova were assayed for enzyme activity. Data are tabulated and 5 photomicrographs are presented. Acid phosphatase activity was greatest in ova of atretic follicles, and moderate in those of growing and graafian follicles. Alkaline phosphatase activity was moderate in the region of the oolemma of larger graafian follicles, and in the zona pellucida of grade 1 atretic follicles, where possibly it was involved in phosphate transport. Glucose-6-phosphate dehydrogenase concentration increased as ova matured, and activity was high in one atretic follicle. The enzyme is a component of the pentose shunt, which may be represented in the ovum. Phosphorylase activity was either absent, or strong, in ova of growing and graafian follicles, and was detected in atretic follicles. The enzyme may be involved in the pentose shunt or Embden-Meyerhof pathway. Occasional detection of isocitrate dehydrogenase might indicate a functioning Krebs cycle, though succinic dehydrogenase was not found in ova at any stage of maturation. Variations in enzyme concentration appeared to relate to follicle maturation, and not to the stage of the oestrous cycle. Continuing enzyme activity in ova of atretic follicles indicated that atresia is initiated in the follicular wall rather than in the ovum.