title: Classification of small type B/C follicles as primordial follicles in mature rats.
abstract: In the present study, follicles were classified according to the morphology of their granulosa cells. Type B follicles contained only flattened granulosa cells; type B/C follicles had a mixture of flattened and cuboidal granulosa cells in a single layer, and type C follicles had a single layer of cuboidal granulosa cells. The primary objectives of the study were to determine whether 5-bromo-2-deoxyuridine incorporation into type B/C follicles was a marker for initiation of growth and how long type B/C follicles could remain at the same stage before transformation to type C follicles. Female Holtzman rats received bromo-deoxyuridine for 7 days. After the infusion (day minipumps were removed = day 0), rats were ovariectomized on days 0 (n = 9), 30 (n = 8), 90 (n = 8) and 150 (n = 9). The numbers of type B, B/C and C follicles within one ovary were determined using modified fractionator counting. Analysis over all times demonstrated that there were more (P < 0.0001) type B/C (941 +/- 61 per ovary) than type C (140 +/- 18 per ovary) or type B (159 +/- 19 per ovary) follicles. The numbers of type B and type C follicles did not differ from each other at any time. Only one of 34 rats evaluated had bromo-deoxyuridine-labelled type B follicles. On day 150, 57% of the bromo-deoxyuridine-labelled type B/C follicles remained from day 0. It is concluded that (1) DNA synthesis in granulosa cells of type B/C follicles is not a reliable indicator of impending growth; and (2) type B and type B/C follicles are both components of the pool of primordial follicles.
authors.affiliation: Cooperative Research, Lincoln University, Jefferson City, MO 65102-0029, USA.
authors.forename: S
authors.initials: S
authors.lastname: Meredith
authors.forename: G
authors.initials: G
authors.lastname: Dudenhoeffer
authors.forename: K
authors.initials: K
authors.lastname: Jackson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001973:Bromodeoxyuridine; D002454:Cell Differentiation; D004247:DNA / Q000096:biosynthesis; D005260:Female; D006080:Ovarian Follicle / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012741:Sexual Maturation / Q000502:physiology*
chemical_list: D004247:DNA; D001973:Bromodeoxyuridine