when a primary follicle enlarges, and there are several layers of granulosa cells, it is called a

get when a primary follicle enlarges, and there are several layers of granulosa cells, it is called a from EN Bilgi.

Female reproductive system: The Histology Guide

Ovarian follicles

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This image shows primordial follicles. Can you identify them, together with the tunica albuginea - the thick collagenous capsule, together with the germinal epithelium that covers it, and the connective tissue in the cortex of the ovary, known as the stroma.

Primordial follicle

Primordial germ cells migrate into the developing gonad early in embryogenesis, and differentiate into oogonia. These oogonia proliferate by mitosis. Some of these enlarge and develop into larger cells called primary oocytes and enter the first meiotic division on the pathway to making gametes by meiosis. This happens between 3 and 8 months of gestation in the human embryo.

These 'primary' oocytes become arrested in prophase of the first meiotic division until the female becomes sexually mature.

At sexual maturity, a small number of primary oocytes (20-50) mature each month and complete the fist meiotic division to become secondary oocytes, under the influence of follicle stimulating hormone. The oocytes synthesise a coat and cortical granules - this glycoprotein coat is called the 'zona pellucida'. They also accumulate ribosomes, yolk, glycogen, lipid and the mRNA that will be used later on after fertilisation to direct early development of the embryo.

After a second mitotic division, ova are formed.

In primordial follicles, the oocyte is arrested in the last stage of prophase (known as dictyotene). At this stage, it is surrounded by a single layer of flattened ovarian follicular epithelial cells. (These cells are also known as granulosa cells).

They are small, and usually found close to the outer edge of the cortex.

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The image shown here, has a primordial follicle. Can you identify it, and the primary oocyte, follicular cells, theca interna and zona pelucida?

Primary follicle

When the primordial follicle is stimulated, it becomes a primary follicle. The oocyte enlarges, and the follicular cells divide. A follicle that has two layers of follicular cells is called a primary follicle. These cells continue to hypertrophy and proliferate to form many layers surrounding the oocyte. Eventually these cells become known as 'granulosa' cells. The granulosa cells will secrete progesterone after ovulation.

A thick glycoprotein layer develops between the oocyte and the zona granulosa, called the zona pellucida.

Finally, the stroma around the follicle develops to form a capsule like 'theca'. (Theca is greek for 'box'). Only one of the maturing follicles completes the maturation process each month. The rest degenerate into atretic follicles. Follicular maturation takes about 3 months.

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This is an image of a secondary follicle. Can you identify the oocyte, theca interna and externa, follicular cells, and follicular fluid?

Secondary Follicle

The primary follicle develops into a secondary follicle.The secondary follicles look very similar to primary follicles, except that they are larger, there are more follicular cells, and there are small accumulations of fluid in the intracellular spaces called follicular fluid (nutritive fluid for the oocyte). These gradually coalesce to form an antrum.

The surrounding granulosa cells is called the cumulus oophorus (greek for 'egg bearing heap').

The surrounding theca differentiates into two layers: the Theca interna (rounded cells that secrete androgens and follicular fluid) and a more fibrous Theca externa - spindle shaped cells. The androgens are converted into oestrogen by the granulosa cells.

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Can you identify the antrum, membrana granulosa, cumulus oophorus, theca externa and theca interna in this image of a Graafian follicle?

Graffian follicle.

The secondary follicle develops into a Graffian follicle.

The first meiotic division is now completed, and the oocyte is now a secondary oocyte, and starts its second meiotic division. After the first meiotic division, most of the cytoplasm goes into one of the two daughter cells. The other becomes the polar body (hard to see).

The folicular fluid fills a single space, called the antrum, which is surrounded by the follicular cells - called the membrana granulosa. The granulosa cells that surround the oocyte, and project into the antrum are called as the cumulus oophorus. There is a basement membrane between the granulosa cells and the theca interna. The fibrous theca externa merges with the surrounding stroma.

Source : www.histology.leeds.ac.uk

Ovarian Follicle

Ovarian Follicle

Graafian follicles can be defined structurally as a heterogeneous family of relatively large follicles (400 μm to >2 cm at ovulation) that display an antrum containing follicular fluid, or liquor folliculi.

From: Endocrinology: Adult and Pediatric (Seventh Edition), 2016

Related terms:

Granulosa CellGonadotropin-Releasing HormoneProgesteroneEicosanoid ReceptorLuteinizing HormoneFollicle-Stimulating HormoneGonadotropinDiethylstilbestrolCorpus LuteumProteome

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Physiology and Pathology of the Female Reproductive Axis

Shlomo Melmed MB ChB, MACP, in Williams Textbook of Endocrinology, 2020

Ovarian Follicle-Stimulating Hormone and Luteinizing Hormone Receptors

The FSH receptor is expressed exclusively by granulosa cells. The LH or hCG receptor (LHCGR) is expressed primarily by the theca-interstitial cells of all follicles and by granulosa cells of large preovulatory follicles.

Granulosa cells in primary or secondary follicles that are in the early developmental stages before antrum formation primarily bind FSH but not LH. In these preantral follicles, the binding of LH or hCG is confined to theca-interstitial cells.85 Granulosa cells in more mature tertiary follicles with an antrum appear capable of binding both LH and FSH. The FSH receptors are found in granulosa cells from follicles of all sizes, but LH receptors are found only in granulosa cells of large preovulatory follicles.86,87 These observations are consistent with the concept that the acquisition of LH receptors on granulosa cells is under the influence of FSH.88

The receptors for the glycoprotein hormones have related structures (seeFig. 17.17, later). The receptors belong to the large family of G protein–coupled receptors, whose members all have a transmembrane domain that consists of seven membrane–traversing α-helices connected by three extracellular and three intracellular loops. The glycoprotein hormone receptors form a separate subgroup within this large family by virtue of their large extracellular hormone-binding domain at the amino-terminus. FSH binds to the FSH receptor, and LH and hCG bind to the same LH receptor. The LH and FSH receptor genes are located on chromosome 2 in the p21 region.47 The carboxy-terminal half of the receptor is encoded by a single last exon and contains the seven transmembrane segments and the G protein–coupling domain. The unusually large extracellular domain of the glycoprotein hormone receptors, on the other hand, is encoded by the first 9 or 10 exons.

Role of Follicle-Stimulating Hormone in Ovarian Function

FSH is the main promoter of follicular maturation. Given that FSH receptors have been exclusively localized to granulosa cells, it is presumed that FSH action in the ovary involves the granulosa cells. The ability of FSH to orchestrate follicular growth and differentiation depends on its ability to exert multiple actions concurrently.

Phenotypes of women with mutations that disrupt the function of the FSH β-subunit gene are in good agreement and demonstrate that FSH is necessary for normal follicular development, ovulation, and fertility. Pubertal development is hampered in the absence of sufficient numbers of later stage follicles with the granulosa cells needed for adequate estrogen production. Treatment of affected patients with exogenous FSH has resulted in follicular maturation, ovulation, and normal pregnancy.47 The presenting phenotype of FSH β-subunit deficiency is practically identical to that caused by inactivating mutations of the FSH receptor, except that the latter fail to respond to exogenous FSH.47

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Vitellogenesis in Fishes☆

B.J. Reading, ... J. Schilling, in Reference Module in Life Sciences, 2017

Introduction

Ovarian follicle growth can be divided into previtellogenic (primary growth) and vitellogenic (secondary growth) stages, during which the major lipid and protein nutrients required for embryonic and larval development are stored within the oocyte (Fig. 1). During previtellogenesis, oocytes begin accumulating neutral lipids, which are stored as lipid droplets in the ooplasm. During vitellogenic growth, oocytes also accumulate phospholipid-rich yolk protein (YP) precursors termed vitellogenins (Vtgs). Vtgs are synthesized by the liver and transported through the bloodstream to the ovary, where they are taken up by oocytes and processed into their derivative YPs. When vitellogenesis ends, the ovary is filled with fully yolked oocytes that subsequently undergo maturation and ovulation. The contribution to oocyte growth of Vtg-derived yolk can be substantial, comprising up to 80–90% of the dry mass of an ovulated egg in some species. The histological structure of vitellogenic ovarian follicles from white perch (Morone americana) is shown in Fig. 2.

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Fig. 1. Model depicting oogenesis in a temperate perciform fish, the white perch (Morone americana). The oocyte along with its surrounding somatic tissues (the granulosa cells and theca layer) is called a follicle. The previtellogenic, primary growth oocyte accumulates neutral lipids that are stored in the ooplasm as lipid droplets. During vitellogenic growth, lipid deposition continues and the oocyte accumulates yolk proteins, which are stored in yolk granules. After vitellogenic growth is completed, the follicle undergoes maturation, which includes resumption of meiosis and cytoplasmic maturation by the oocyte, culminating in ovulation of an egg that is competent to undergo fertilization.

Source : www.sciencedirect.com

Bio 156 SM Quiz Lesson 12 Flashcards

Start studying Bio 156 SM Quiz Lesson 12. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

Bio 156 SM Quiz Lesson 12

Which of the following ovarian hormones is involved in a positive feedback loop with the hypothalamus and the anterior pituitary?

A) progesterone

B) luteinizing hormone

C) gonadotropin releasing hormone

D) estrogen E) gonadotropin

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D) estrogen

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Which of the following hormones is released by the anterior pituitary as a part of that positive feedback loop between it and the ovary?

A) progesterone

B) luteinizing hormone

C) gonadotropin releasing hormone

D) estrogen E) gonadotropin

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B) luteinizing hormone

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Terms in this set (20)

Which of the following ovarian hormones is involved in a positive feedback loop with the hypothalamus and the anterior pituitary?

A) progesterone

B) luteinizing hormone

C) gonadotropin releasing hormone

D) estrogen E) gonadotropin D) estrogen

Which of the following hormones is released by the anterior pituitary as a part of that positive feedback loop between it and the ovary?

A) progesterone

B) luteinizing hormone

C) gonadotropin releasing hormone

D) estrogen E) gonadotropin

B) luteinizing hormone

Which of the following hormones is released by the corpus luteum after ovulation and causes a negative feedback loop with the hypothalamus and the anterior pituitary?

A) progesterone

B) luteinizing hormone

C) gonadotropin releasing hormone

D) estrogen E) gonadotropin A) progesterone

A positive feedback loop causes a self-amplifying cycle where a physiological change leads to even greater change in the same direction.

A) True B) False A) True

A negative feedback loop is a process in which the body senses a change, and activates mechanisms to reverse that change.

A) True B) False A) True

When a primary follicle enlarges, and there are several layers of granulosa cells, it is called a...

A) primordial follicle.

B) primary follicle.

C) secondary follicle.

D) mature follicle. E) corpus luteum.

C) secondary follicle.

Which of the following has an antrum?

A) primordial follicle

B) primary follicle

C) secondary follicle

D) mature follicle E) corpus luteum D) mature follicle

Which of the following is involved in ovulation?

A) primordial follicle

B) primary follicle

C) secondary follicle

D) mature follicle E) corpus luteum D) mature follicle

At full maturity, an oocyte is located in the corona radiata.

A) True B) False B) False

During ovulation, the oocyte is surrounded by some of the cells of the corona radiata called the cumulus mass.

A) True B) False B) False

Spermatogenesis occurs in the

A) epididymis.

B) seminiferous tubules.

C) prostate gland. D) vas deferens. E) seminal vesicle.

B) seminiferous tubules.

Which of the following is a correct sequence of cells in spermatogenesis?

A) spermatogonium -> primary spermatocyte -> secondary spermatocyte

B) spermatogonium -> secondary spermatocyte -> primary spermatocyte

C) primary spermatocyte -> secondary spermatocyte -> spermatogonium

D) primary spermatocyte -> spermatogonium -> secondary spermatocyte

E) none of the above

A) spermatogonium -> primary spermatocyte -> secondary spermatocyte

During spermatogenesis, which of the following cells is the first to become haploid?

A) primary spermatocyte

B) secondary spermatocyte

C) sperm cells D) spermatid E) spermatogonium

B) secondary spermatocyte

Meiosis II of spermatogenesis results in the formation of secondary spermatocytes.

A) True B) False B) False

During spermatogenesis, spermatids differentiate into spermatozoa.

A) True B) False A) True

What was one of the requests made by the fertility physician's patient?

A) To place her harvested eggs in a surrogate donor.

B) To find viable sperm donors for her eggs.

C) To harvest her eggs and freeze them until she was ready to use them.

D) To clone a frozen embryo of hers.

C) To harvest her eggs and freeze them until she was ready to use them.

What was one of the perceived impasses of fulfilling her requests?

A) There have been no successful embryo's conceived by donor sperm.

B) Her age made it a bad option for harvesting her eggs and using them.

C) Her body rejected all fertility drugs used.

D) There have been no frozen embryo's implanted successfully.

B) Her age made it a bad option for harvesting her eggs and using them.

What was dehydroepiandrosterone being sold for as an over the counter medication?

A) It is a commonly used fertility drug.

B) It stimulates sperm production in males.

C) It is a natural alternative to estrogen replacement therapy.

D) It has been marketed as an anti-aging drug.

D) It has been marketed as an anti-aging drug.

What happened to the individual who coupled the fertility drugs with DHEA?

A) She remained unsuccessful in conceiving a child.

Source : quizlet.com