primordial follicle

https://doi.org/10.1351/goldbook.11132

Early stage of the oocyte in which it is surrounded by a single layer of follicular cells.

See also: follicle
Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 796 [Terms] [Paper]