Female Germ Cell Development in Chickens and Humans: The Chicken Oocyte Enriched Genes Convergent and Divergent with the Human Oocyte

Abstract

The development of germ cells and other physiological events in the differentiated ovary of humans are highly conserved with several mammalian species, except for the differences in timing. However, comparative knowledge on this topic is very scarce with respect to humans and lower vertebrates, such as chickens. In chickens, female germ cells enter into meiosis around embryonic day (E) 15.5 and are arrested in meiotic prophase I as primary oocytes. The oocytes arrested in meiosis I are accumulated in germ-cell cysts; shortly after hatching, they are enclosed by flattened granulosa cells in order to form primordial follicles. In humans, the process of meiotic recombination in female germ cells begins in the 10–11th week of gestation, and primordial follicles are formed at around week 20. In this review, we comprehensively elucidate both the conservation and the species-specific differences between chickens and humans with respect to germ cell, oocyte, and follicle development. Importantly, we provide functional insights into a set of chicken oocyte enriched genes (from E16 to 1 week post-hatch) that show convergent and divergent expression patterns with respect to the human oocyte (from week 11 to 26).

Pronounced early differentiation underlies zebra finch gonadal germ cell development

“…cGCs showed progressive declines in gene expression of several stem cell markers (e.g., NANOG, PRDM14 , LIN28A) , though sizeable expression only persisted in the male HH36 gonadal dataset (Figure 7A). In contrast, several genes showed differential expression patterns between female HH35 and HH36 germ cells (Figure 7A; Supplemental table 24), corresponding with the RA-mediated onset of oogenesis in chicken around this developmental stage (Rengaraj and Han, 2022; Smith et al, 2008). The loss of NANOG and other pluripotent markers coincided with FOXL2L expression in female HH36 germ cells, matching the known onset of FOXL2L upregulation in the left gonad of female chicken embryos at E9 (Ichikawa et al, 2019).…”

Integration of transcriptome sequencing and whole genome resequencing reveal candidate genes in egg production of upright and pendulous-comb chickens

“…RNA also plays some roles in chicken follicular development ( Peng et al, 2019 ). In addition, maternal RNAs and proteins in the oocyte are important for the early development of precursor cells of the oocyte in chicken ( Rengaraj et al, 2020 ; Rengaraj and Han, 2022 ). Based on these processes, it is obvious that the DEGs involved between the ovary tissues of PC and UC chickens might be associated with egg production performance.…”

Identification of potential angiogenic biomarkers in human follicular fluid for predicting oocyte maturity

“…Eotaxin binds to human endothelial cells to induce endothelial proliferation and migration ( 31 , 32 ). Elevated eotaxin expression in FF might play an important role in angiogenesis and oocyte maturation during the stage of ovarian angiogenesis between the LH surge and meiosis completion ( 33 , 34 ). This phenomenon would explain the higher eotaxin level observed in the preovulatory follicle during IVF.…”