Abstract: 449

STEREOLOGICAL CHARACTERIZATION OF BOVINE CUMULUS-OOCYTE COMPLEXES (COCs) ASPIRATED FROM SMALL ANTRAL FOLLICLES DURING THE DIESTROUS PHASE.

AM Calado¹ , E Rocha² , A Colaço¹ , M Sousa^{3 *}
Section of Pathology and Vet Clinics, UTAD, Vila Real, Portugal ¹
Lab of Histology and Embryology, Institute of Biomedical Sciences, Univ of Porto, Porto, Portugal ²
Lab of Cell Biology, Institute of Biomedical Sciences, Univ of Porto, Porto, Portugal ³

A stereological characterization of cumulus-oocyte complexes (COCs) from Bos taurus follicles would help to establish a correlation between morphology and developmental competence. Twenty four COCs with a compact and complete cumulus mass, with three or more follicular cell layers, and with a homogeneous ooplasm were selected under a stereomicroscope. After fixation, COCs were embedded in glycol methacrylate, totally cut into 20 µm sections, and stained with methylene blue and azur II (2:1). The optical disector, the nucleator and a variety of this technique (virtual-point nucleator), were used to estimate the mean volumes of the complexes (33 x 10⁶ µm³; CV=0.68), oocytes (1.5 x 10⁶ µm³; CV=0.76), and oocyte nuclei (69 x 10³ µm³; CV=2.83), as well as the mean volumes of follicular cells and their nuclei. Mean volumes of follicular cells enabled us to identify three different cell populations (C1, C2, C3) but only two (C1, C3) were significantly distinct cell: type C1 (mean volume of 551 µm³, CV=0.38), with a highly dense nucleus (mean volume of 108 µm³, CV=0.50), and type C3 (mean volume of 1987 µm³, CV=1.36), with a light nucleus (mean volume of 605 µm³, CV=0.64). Cell type C2 was only significantly different from C3 (mean volume of 807 µm³, CV=0.34), with an intermediate dense nucleus (mean volume of 200 µm³, CV=0.38). Almost 82% of the COCs presented C1, C2 and C3, whereas 6% had only C2 and C3, and 12% had exclusively C3. The cumulus mass was composed in average by 15.7% of C1, 32.4% of C2 and 51.9% of C3. This category of COCs was morphologically heterogeneous, regarding to oocyte and follicular cells. Types C1 and C3 may correspond to the same cell at different physiological status, and cell type C2 probably is a C1 subtype.

    This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.