Question

In the diagram of the section of the Graffian follicle,different parts are indicated by the alphabets;choose the answer in which these alphabets have been correctly matched with the parts they indicate.

A-Theca externa B-Theca interna C-Ovum D-Membrane granulosa E-Antrum F-Cumulus Oophorus
A-Membrane granulosa B-Theca interna C-Ovum D-Cumulus Oophorus E-Antrum F-Theca externa
A- Membrana granulosaB-Theca externa C-Ovum D-Cumulus Oophorus E-Antrum F- Theca interna
A-Theca externa B-Theca interna C-Ovum D-Cumulus Oophorus E-Antrum F-Membrane granulosa

Answer 1

Hint: After the first meiotic division but before ovulation, the Graafian Follicle is the follicular level. Consequently, it contains a 2N haploid oocyte. It is defined by a broad follicular antrum that forms the majority of the follicle.

Complete answer:
During the embryonic development stage, when inside each foetal ovary a few million gamete mother cells (oogonia) are produced, oogonia is initiated; no more oogonia are formed and added after birth. These cells begin to divide into prophase-I and enter the meiotic division and are temporarily arrested at that stage, called primary oocytes.

The presence of a follicular antrum inside the granulosa layer is the unique characteristic attribute that separates secondary from primary follicles. The antrum contains fluid which is rich in proteoglycans and hyaluronan. Note that the cell layers of the granulosa zone, the thicker pellucida zone, and the larger oocyte zone have increased. A layer of cells outside the follicle is obvious at this point. The theca interna consists of these cells and contributes to the production of estrogens.

A layer of granulosa cells is then surrounded by each primary oocyte and then called the primary follicle. Over the time from birth to puberty, a significant number of these follicles degenerate. Hence only 60,000-80,000 primary follicles are left in each ovary at puberty. More layers of granulosa cells (label F) and a fresh theca are covering the primary follicles and are called secondary follicles.

The secondary follicle soon becomes a tertiary follicle, distinguished by a cavity filled with fluid called an antrum (label E).
The theca layer is divided into an internal theca interna (label B) and an external theca externa (label A).

At this stage, the primary oocyte grows in size and completes its first meiotic division within the tertiary follicle. It is an unequal division that results in a broad haploid secondary oocyte or ovum (label C) and a tiny first polar body being created. The cumulus oophorus (label D) is a cluster of cells (called cumulus cells) that surround the oocyte in both the ovarian follicle and after ovulation, also known as the discus proligerus.

Hence, the correct answer is option (D)

Note: A broad follicular antrum, which makes up much of the follicle, characterises the follicle. The secondary oocyte is placed eccentrically , having undergone the first meiotic division. The zona pellucida and a layer of many cells known as the corona radiata surround it. The ovum consists of three structures when released from the Graafian follicle and into the oviduct: oocyte, zona pellucida and corona radiata.