Corona radiata ( embryology ) - Wikipedia Corona radiata ( embryology ) This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources. ( June 2013 ) Corona radiata Human ovum examined fresh in the liquor folliculi. The zona pellucida is seen as a thick clear girdle surrounded by the cells of the corona radiata. The egg itself shows a central granular deutoplasmic area and a peripheral clear layer, and encloses the germinal vesicle, in which is seen the germinal spot. Anatomical terminology ( edit on Wikidata ) For the structure in neuroanatomy, see Corona radiata. The corona radiata is the innermost layer of the cells of the cumulus oophorus and is directly adjacent to the zona pellucida, the outer protective glycoprotein layer of the ovum. Its main purpose in many animals is to supply vital proteins to the cell. It is formed by follicle cells adhering to the oocyte before it leaves the ovarian follicle, and originates from the squamous granulosa cells present at the primordial stage of follicular development. The corona radiata is formed when the granulosa cells enlarge and become cuboidal, which occurs during the transition from the primordial to primary stage. These cuboidal granulosa cells, also known as the granulosa radiata, form more layers throughout the maturation process, and remain attached to the zona pellucida after the ovulation of the Graafian follicle. For fertilization to occur, sperm cells rely on hyaluronidase ( an enzyme found in the acrosome of spermatozoa ) to disperse the corona radiata from the zona pellucida of the secondary ( ovulated ) oocyte, thus permitting entry into the perivitelline space and allowing contact between the sperm cell and the nucleus of the oocyte. References Jump up ^ Gilbert, Scott F. Developmental Biology ( Ninth ed. ). Sinauer Associates, Inc. p. 126. ISBN 0878933840. External links Image at Berkeley Histology image : 18404loa -- Histology Learning System at Boston University Animation : Maturation of the Follicle and Oocyte Female reproductive system Internal Adnexa Ovaries Follicles corpus hemorrhagicum luteum albicans Theca of follicle externa interna Follicular antrum Follicular fluid Corona radiata Zona pellucida Membrana granulosa Perivitelline space Other Germinal epithelium Tunica albuginea cortex Cumulus oophorus Stroma Medulla Fallopian tubes Isthmus Ampulla Infundibulum Fimbria Ostium Ligaments Ovarian ligament Suspensory ligament Wolffian vestiges Gartner 's duct Epoophoron Vesicular appendages of epoophoron Paroophoron Uterus Regions Body Uterine cavity Fundus Cervix External orifice Cervical canal Internal orifice Supravaginal portion Vaginal portion Uterine horns Layers Endometrium epithelium Myometrium Perimetrium Parametrium Ligaments Round ligament Broad ligament Cardinal ligament Uterosacral ligament Pubocervical ligament General Uterine glands Vagina Fossa of vestibule of vagina Vaginal fornix Hymen External Vulva Labia Mons pubis Labia majora Anterior commissure Posterior commissure Pudendal cleft Labia minora Frenulum of labia minora Frenulum of clitoris Vulval vestibule Interlabial sulci Bulb of vestibule Vaginal orifice vestibular glands / ducts Bartholin 's glands / Bartholin 's ducts Skene 's glands / Skene 's ducts Clitoris Crus of clitoris Corpus cavernosum Clitoral glans Hood Urethra Urethral crest Other G - spot Urethral sponge Perineal sponge This developmental biology article is a stub. You can help Wikipedia by expanding it. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Corona_radiata_(embryology)&oldid=774975568 '' Categories : Mammal female reproductive system Developmental biology stubs Hidden categories : Articles needing additional references from June 2013 All articles needing additional references Articles which use infobox templates with no data rows Medicine infobox template using GraySubject or GrayPage All articles with unsourced statements Articles with unsourced statements from August 2009 All stub articles Talk About Wikipedia Español Français Italiano Nederlands Polski Português Suomi Svenska Edit links This page was last edited on 11 April 2017, at 20 : 57. About Wikipedia

Question: which follicle stage is characterized by the development of a corona radiata
Answer: the transition from the primordial to primary stage