Developmental Stages of Primary Oocytes in Turkeys

Abstract

Little is known about the growth and differentiation of the primary oocyte in the sexually mature chicken or turkey hen. In this study, primary oocytes from turkey hens in egg production were examined by light and electron microscopy. Based on oocyte and germinal vesicle (GV) diameters and organelle morphology and distribution, the sequential development of the primary oocyte was divided into five stages. No Balbiani body was observed in Stage I oocytes (< 80 microns in diameter). Pleomorphic mitochondria were localized around the GV and multivesicular bodies were scattered in the ooplasm. By Stage II (81 to 150 microns), the Balbiani body was observed adjacent to the GV. Pleomorphic mitochondria, macrobodies, and smooth endoplasmic reticulum (SER) were associated with the Balbiani body. Lipid droplets were predominantly localized to the periphery of the oocyte. The Balbiani body was partially dispersed by Stage III (151 to 350 microns) and associated organelles appeared in clusters in the ooplasm. Golgi and SER were observed immediately subjacent to the oolemma. Stage IV oocytes (351 to 500 microns) were characterized by the absence of the Balbiani body, a more centrally located GV, and the redistribution of the mitochondria to the periphery of the oocyte. Throughout the ooplasm was vesicular SER. By Stage V (501 to 800 microns), zonation of the organelles was completed with the mitochondrial ring immediately subjacent to the oolemma and a concentric layer of lipid droplets subjacent to the mitochondrial ring. The GV was in the periphery of the oocyte. Organelle and inclusion redistribution and organelle pleomorphism were presumed to be reflective of increasing metabolic and transport requirements of the growing oocyte in the mature turkey hen.

Oogenesis in cultures derived from adult human ovaries

“…Dispersion of Balbiani bodies releases mitochondria required for the progressive growth of the oocyte. In a study of turkey hens, no Balbiani bodies were detected in stage I oocytes, but they appeared in stage II oocytes, and diminished in the oocytes of growing follicles, coinciding with the dispersion of mitochondria throughout the ooplasm [29]. Similar observations were reported in human oocytes [30].…”

Retraction: Detection, Characterization, and Spontaneous Differentiation In Vitro of Very Small Embryonic-Like Putative Stem Cells in Adult Mammalian Ovary

“…The oocyte-like structures appeared to grow in close vicinity of mesenchymal fibroblasts (Fig. 8) and this close association has been earlier implied to demonstrate the nutritional support, aromatase expression which catalyzes the turnover of C [19] steroids into estrogens, and also as a source of energy by mitochondrial trafficking provided to the growing germ cells by the surrounding somatic cells [21,25,[53][54][55][56]. It is tempting to speculate that these fibroblast cells derived by EMT may act as the supporting somatic granulosa cells for the maturing oocyte-like structures derived from putative OSE stem cells.…”

Ovarian Stem Cell Niche and Follicular Renewal in Mammals

“…The Balbiani body contains aggregated mitochondria and can be observed in primordial follicles in both fetal and adult ovaries (Carlson et al, 1996;Motta et al, 2000;Cox and Spradling, 2003). In a study of turkey hens, no Balbiani body was detected in Stage I oocytes, appeared in Stage II oocytes, and diminished in the oocytes of growing follicles, coinciding with the dispersion of mitochondria throughout the ooplasm (Carlson et al, 1996).…”