While observing a transverse section of a human ovary under a microscope, a student identifies a developing follicle. The follicle exhibits a prominent fluid-filled cavity, and its theca is distinctly organised into an inner and an outer layer. Within this follicle, the large central cell has just completed an unequal division, resulting in the extrusion of a tiny first polar body. Identify the stage of the follicle

Step-by-step solution

According to NCERT, the tertiary follicle is characterised by a fluid-filled cavity called the antrum, and its theca layer is organised into an inner theca interna and an outer theca externa. It is at this specific stage that the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division. This is an unequal division that results in the formation of a large haploid secondary oocyte and a tiny first polar body. Therefore, the follicle described is a tertiary follicle, and the l