Kinetics of Follicle Growth in the Prepubertal Gilt

Abstract

Follicular growth rates were determined by histological examination of ovaries of five prepubertal gilts following treatment with the stathmokinetic agent colchicine. One ovary from each of five gilts was removed surgically and then colchicine (n = 3) or saline (n = 2) was infused i.v. Precisely 2 h after treatment with colchicine, the remaining ovary was removed. Ovaries were processed for histological analyses and sectioned at 10 microns; every twentieth section was stained with hematoxylin and periodic acid-Schiffe's. Sections were viewed with a projection microscope and individual follicles were measured. Eight classes of follicles were established such that the number of granulosa cells per cross section doubled in each class. Diameters of follicles for each class were as follows: 1) less than 106 microns, 2) 106-148 microns, 3) 148-206 microns, 4) 206-287 microns, 5) 287-400 microns, 6) 400-657 microns, 7) 657-1480 microns, and 8) 1480-3130 microns. A layer of thecal cells was first seen in class 2 follicles, and 76% of class 3 follicles had a thecal layer. Oocyte diameter increased through the first four classes and reached a maximum diameter of approximately 110 microns. Almost all follicles greater than 400 microns had an antrum. Preantral follicles had a lower mitotic index and a higher mitotic time and class time than antral follicles. Growth rate increased with increasing size of follicles. Preantral follicles grew at a rate of 5.2 microns/day whereas antral follicles grew at 313 microns/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular supply as a discriminating factor for pig preantral follicle selection

“…To achieve this aim, somatic index (PI), proportion of PEs (PE/PT), VA and VEGFA expression (VEGFA mRNA and protein) were simultaneously recorded on single healthy preantral follicles classified into six different stages of development as proposed by Morbeck et al (1992). This precise morphological classification was adopted to better interpret the data obtained, distinct from other studies where preantral follicles were considered as early or late structures when the granulosa compartment was organized in less or more than four granulosa layers respectively (Wulff et al 2002, Danforth et al 2003, Roberts et al 2007).…”

“…On two or more HE sections, mean follicular diameter was calculated using the KS300 computed image analysis system (Zeiss), set to measure two diameters of the follicle/oocyte section at right angles and only symmetrical follicles (right angle cross sections within 10% of each other) were considered (Morbeck et al 1992). Since in the early stages of preantral follicles the outer boundary of the theca layers could not be defined precisely, the follicular diameter was always measured from the basement membrane immediately outside the granulosa cells (Lundy et al 1999, Griffin et al 2006.…”

“…The morphometric parameters (follicle diameters and number of granulosa cell layers) were calculated by two investigators in a blinded fashion, and the correlation coefficient for follicle counts between the two investigators (Zimmermann et al 2003) was 0.915. On the basis of mean follicular diameter and the number of granulosa layers, preantral follicles were classified into six different categories adopting, with minor modifications, the classification developed by (Morbeck et al 1992) -class 1: !65 mm and 1-2 layers of granulosa cells, -class 2: from 65 to 110 mm with 2-4 layers of granulosa cells, -class 3: from 111 to 180 mm with 5-7 layers of granulosa cells, -class 4: from 181 to 240 mm with 8-10 layers of granulosa cells, -class 5: from 241 to 300 mm with 11-13 layers of granulosa cells and -class 6: follicular diameter O300 mm with O13 layers of granulosa cells.…”

“…To address this aim, several parameters such as granulosa, theca and endothelial cell proliferation, vascular area (VA), and VEGFA intrafollicular distribution have been studied. These analyses were simultaneously performed on single preantral follicles that were previously classified on the basis of the morphological stage of development (Morbeck et al 1992). The variables were then statistically evaluated to examine the relationship existing between the aboveexamined parameters and the different categories of preantral follicles.…”

Effects of gonadotrophin treatments on meiotic and developmental competence of oocytes in porcine primordial follicles following xenografting to nude mice

“…Kinetic analyses of follicular growth in the prepubertal gilts estimate that growth of follicles from antrum formation to a diameter of 3 mm or more requires approximately 14 days (Morbeck et al 1992). In this study, therefore, we stimulated follicular growth in the xenografts with porcine FSH for 1 or 2 weeks and the resultant follicular growth and oocytes viability were compared with those after eCG treatment described in our previous studies (Kaneko et al 2003, Kikuchi et al 2006.…”