# Ovary Histology > Ovary histology for MBBS Anatomy: germinal epithelium, follicle stages from primordial to Graafian, corpus luteum, atresia and clinical correlates. - Canonical URL: https://prepelephant.com/topics/mbbs/anatomy/ovary-histology - Exam / course: MBBS · Subject: Anatomy - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Ovary Histology", PrepElephant, https://prepelephant.com/topics/mbbs/anatomy/ovary-histology ## Direct answer A single section through an ovary reads like a timeline: follicles at every stage crowd the cortex around a fibrocellular medulla, and the stage you see tells you the phase of the cycle. The surface is covered by a simple cuboidal layer called — misleadingly — the germinal epithelium, a modified peritoneum that is the origin of most ovarian carcinomas yet contributes no oocytes. Beneath it, primordial follicles (a primary oocyte arrested in prophase of meiosis I, ringed by a single flat cell layer) wait from foetal life; recruitment builds them through primary and secondary stages to the Graafian follicle with its antrum, cumulus oophorus and corona radiata. After ovulation, granulosa and theca cells luteinise into the progesterone-secreting corpus luteum, which regresses to the pale corpus albicans unless pregnancy rescues it. ## What you must remember - **Surface epithelium:** simple cuboidal "germinal" epithelium, a peritoneal derivative — source of most ovarian malignancies (serous, mucinous, endometrioid tumours). - **Primordial follicle:** primary oocyte arrested at diplotene of meiotic prophase I in a single flat follicular layer; the lifetime stock falls from about 6-7 million at 20 weeks' gestation to 1-2 million at birth and 300,000-400,000 at puberty, of which only around 400 ever ovulate. - **Primary follicle:** follicular cells turn cuboidal then multilayered granulosa, and the zona pellucida appears between oocyte and granulosa. - **Secondary (antral) follicle:** Call-Exner bodies in the granulosa, antrum forming, theca interna (vascular, oestrogen-secreting) and theca externa (fibrous) differentiated. - **Graafian follicle:** dominant antrum, oocyte on the cumulus oophorus with corona radiata; meiosis I completes just before ovulation, arresting at metaphase II. - **Corpus luteum:** granulosa lutein (progesterone) and theca lutein (oestrogen) cells; regresses to corpus albicans in about 14 days without human chorionic gonadotrophin. - **Atresia:** the fate of over 99 per cent of follicles — granulosa apoptosis with theca hypertrophy adding to the ovarian stroma of later life. - **Clinical anchors:** polycystic ovary shows a thickened tunica with multiple atretic and cystic follicles; dermoids arise from germ cells. ## Dating an ovary from one field of view Pick the largest follicle and classify it. A single flat layer around a pale oocyte is primordial and could belong to any ovary from birth to menopause; multilayered granulosa with a visible zona pellucida means recruitment has begun. When an antrum appears, follicle-stimulating-hormone dependence is established, and when the antrum dominates with the oocyte on its cumulus hilllock, you are looking at a preovulatory Graafian follicle, up to about 2 centimetres across at mid-cycle. If the field is a convoluted ribbon of large, eosinophilic, lipid-laden cells forming a yellow mass with a central clot, you have a corpus luteum, dating the ovary to the luteal phase or early pregnancy; rescue by human chorionic gonadotrophin converts it into the corpus luteum of pregnancy until the placenta takes over. A white, hyaline scroll of collagen is a corpus albicans, and many such scars plus scanty primordial follicles is the signature of the perimenopausal ovary. ## Where students slip Three confusions recur. First, the term germinal epithelium implies it generates oocytes; it does not — oogonia are germ-cell lineage set down in foetal life, while the surface is peritoneal mesothelium and the commonest tumour origin in this organ. Second, theca versus granulosa in steroid production: the avascular granulosa lacks the early enzymatic steps, so theca cells synthesise androgen substrate that granulosa aromatises to oestradiol — the two-cell theory, asked across anatomy, physiology and gynaecology. Third, meiotic timing: the oocyte hangs in prophase I until the luteinising-hormone surge, finishes meiosis I at ovulation releasing the first polar body, and completes meiosis II only if a sperm penetrates. ## Frequently asked questions ### Why is the term germinal epithelium a misnomer? It is modified peritoneal mesothelium that generates no germ cells; oocytes derive from yolk-sac germ cells, while the surface layer is the source of most ovarian carcinomas. ### Which follicle stage is FSH-dependent and develops an antrum? The secondary (antral) follicle onwards — antrum formation marks the recruitment cohort from which one dominant follicle emerges each cycle. ### Which cells form the corpus luteum and what do they secrete? Luteinised granulosa cells chiefly secrete progesterone and luteinised theca cells oestrogen, sustaining the secretory endometrium. ### When does the primary oocyte complete meiosis I? Just before ovulation under the luteinising-hormone surge, releasing the first polar body and arresting at metaphase II until fertilisation. ### What distinguishes polycystic ovary histology? A thickened tunica albuginea with multiple subcapsular atretic and cystic follicles — the anatomy behind anovulation and hyperandrogenism.