Category Archives: Follicle

Many oocytes of antral follicles appeared to express reduced levels of KIT protein compared with those of smaller growing follicles (Fig. 4b). Intensely stained granules also were detected at the oolemma and in the cytoplasm of oocytes from primordial through antral follicles (Fig. 4, b-d). KIT protein was weakly detected in the theca cells of some preantral and antral follicles (not shown). All other somatic cells within the ovary were free of KIT immunoreactivity. Specific staining was not detected when antiserum was substituted with preimmune serum (Fig. 4a). (more…)

KIT Protein Expression in Juvenile Rabbit Ovaries At 2 wks of age, KIT protein was detected at very low levels in the outer cortex of the ovary, whereas higher concentrations of the protein were localized toward the inner region of the ovary (not shown). Very weak KIT immunostaining was observed within naked oocytes located closest to the ovarian epithelium. Closer to the medulla the intensity of KIT immunoreactivity was variable, with KIT protein expression detected in some naked oocytes. (more…)

While some of the germ cell clusters in the outer cortex were entirely devoid of staining, others contained a mixture of Kit-positive and Kit-negative oocytes (Fig. 3b). Kit mRNA was not detected in any somatic cells within 2-wk-old rabbit ovarian tissue (Fig. 3, a and b). (more…)

The cuboidal granulosa cells of most activated and growing follicles expressed high levels of KITL protein (Fig. 2, c and d). No difference in granulosa cell staining intensity was detected within or between preantral follicles. In contrast, the granulosa cells of large antral follicles appeared to express varying levels of KITL (not shown). In most large antral follicles, granulosa cell KITL expression was very low, whereas in very few follicles at this stage low to moderate KITL protein expression was evident in both mural and cumulus granulosa cells (not shown). (more…)

KITL Protein Expression in Juvenile Rabbit Ovaries Similar to the results obtained by in situ hybridization, in the 2-wk-old rabbit ovary intense KITL immunostaining was observed in the outer cortex, with considerably less staining evident toward the medulla (not shown). KITL protein was strongly localized to the somatic cells associated with nests of naked oocytes, whereas the oocytes within the nests exhibited very diffuse staining. The somatic cells of the stroma located between the clusters of germ cells did not stain for KITL protein. KITL immunoreactivity was weakly detected in the granulosa cells and oocytes of the newly formed follicles located toward the medulla of the 2-wk-old ovary. (more…)

The pattern of staining in ovarian tissue from 4- to 12-wk-old rabbits remained the same among age groups, with comparatively low levels of expression in primordial follicles, high expression levels in growing preantral follicles, and variable expression levels in antral follicles (Fig. 1, c-e). Kitl mRNA occasionally was observed in the flattened granulosa cells surrounding some primordial follicles (Fig. 1, c and d). In early primary follicles the cuboidal granulosa cells nearly always expressed Kitl (Fig. 1d), whereas the flattened granulosa cells within the same follicle often remained free of staining (Fig. 1d). Growing follicles from the primary stage onward expressed high levels of Kitl in almost every granulosa cell (Fig. 1e). (more…)

Moreover, a series of three lysine residues (amino acids 213, 214, and 215) adjacent to the transmembrane domain of KITL are present in the rabbit, mouse, rat, and bovine amino acid sequence. These charged residues may serve to anchor the mature protein in the membrane (see Supplemental Fig. 1). (more…)

Characterization of Rabbit Kitl cDNA The nucleotide sequence for the coding region of rabbit Kitl was 91%, 90%, 89%, and 89% identical at the nucleotide level to human, mouse, rat, and bovine Kitl, respectively. The deduced amino acid sequence of the cDNA was 86%, 86%, 84%, and 84% identical to human, mouse, rat, and bovine KITL, respectively (see Supplemental Fig. 1). These data indicate substantial interspecies conservation at gene and protein levels. (more…)

A considerably higher proportion of follicles in rabbit ovarian cortical explants degenerated in culture compared with follicles in mouse ovaries, possibly due to the extensive dissection undertaken to generate rabbit ovarian cortical explants which was not required for the preparation of mouse ovaries for culture. It is also possible that the culture system employed did not adequately support the development of later-stage rabbit follicles. However, given that at the initiation of culture the majority of follicles were in the primordial and early primary stage, whereas at the end of the culture period healthy multilayered growing follicles were often observed, we suggest that the growth and development of early rabbit follicles in vitro was supported by this culture system. A definite role for KITL in later follicle development would need to be addressed by the use of an isolated follicle rather than the explant culture system described above. (more…)

Primary follicles were those surrounded by a complete layer of cuboidal granulosa cells. Growing primary follicles had multiple layers of granulosa cells along one side and a single layer on another. Preantral follicles had two or more complete layers of granulosa cells in the absence of an antrum. Small antral follicles had patchy fluid-filled zones between the granulosa layers, whereas in large antral follicles the fluid patches had merged into a single large cavity. Antral follicles were not observed in cultured ovaries and explants. (more…)