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Answer the following question. Explain the histological structure of ovary in human. - Biology

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Answer in Brief

Answer the following question.

Explain the histological structure of ovary in human.

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Solution 1

Histological structure of ovary:

Each ovary is a compact structure differentiated into a central part called medulla and the outer part called the cortex. The cortex is covered externally by a layer of germinal epithelium. The stroma of loose connective tissue of the medulla has blood vessels, lymph vessels, and nerve fibers.
The outer cortex is more compact and granular.
It shows large number of tiny masses of cells called ovarian follicles. These are collectively formed from the immature ova originating from cells of the dorsal endoderm of the yolk sac. The cells migrate to the gonadal ridge during embryonic development and divide mitotically.
Now these cells are called oogonia.

As the oogonia continue to grow in size they are surrounded by a layer of granulosa cells. This assembly forms the rudiments of the ovarian follicles. The process of oogenesis starts much before the birth of the female baby and by the end of twelve weeks the ovary is fully formed. The ovary has more than two million primordial follicles in it. The cells of the germinal epithelium give rise to groups of oogonia projecting into the cortex in the form of cords called egg tubes of Pfluger. Each cord at its end has a round mass of oogonial cells called egg nests, from which the primordial ovarian follicles develop. Each primordial follicle has, at its center a large primary oocyte (2n) surrounded by a single layer of flat follicular cells. The primary oocyte starts with its meiotic division but gets arrested it at meiosis I.
Of the two million primordial follicles embedded in the fetal ovary only about one million remains at birth and only about 40,000 remain at the time of puberty.

T.S. of Ovary-

The histological structure of the ovary shows the different stages of development of the oocyte in the ovary. These changes are cyclic and occur during each menstrual cycle. This development involves maturation of the primordial follicles into primary, secondary and Graafian follicles.

Each primary follicle has multi-layered cuboidal follicular cells. The stroma cells add theca over the follicle, which then changes into a secondary follicle.

There is the growth of the oocyte and the granulosa cells increase in number. They start producing the hormone estrogen.
The secondary follicle grows into the Graafian follicle by the addition of more follicular cells.
As this process of maturation of follicles takes place, they begin to move towards the surface of the ovary. The Graafian follicle presses against the thin wall of the ovary giving it a blistered appearance.
The egg is released from the Graafian follicle during ovulation and the remaining part of the follicle changes into a temporary endocrine gland called corpus luteum.
If fertilization does not take place the corpus luteum degenerates into a white scar called corpus albicans.

Solution 2

The histological structure of the ovary shows the different stages of development of the oocyte in the ovary. These changes are cyclic and occur during each menstrual cycle. This development involves the maturation of the primordial follicles into primary, secondary, and Graafian follicles.

  1. Each primary follicle has multi-layered cuboidal follicular cells.
  2. The stroma cells add theca over the follicle, which then changes into a secondary follicle.
    There is the growth of the oocyte and the granulosa cells increase in number. They start producing the hormone estrogen.
  3. The secondary follicle grows into the Graafian follicle by the addition of more follicular cells.
    As this process of maturation of follicles takes place, they begin to move towards the surface of the ovary. The Graafian follicle presses against the thin wall of the ovary giving it a blistered appearance.
    The egg is released from the Graafian follicle during ovulation and the remaining part of the follicle changes into a temporary endocrine gland called the corpus luteum.
    If fertilization does not take place the corpus luteum degenerates into a white scar called corpus albicans.
Concept: Sexual Reproduction in Animals
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APPEARS IN

Balbharati Biology 12th Standard HSC for Maharashtra State Board
Chapter 2 Reproduction in Lower and Higher Animals
Exercises | Q 5.05 | Page 48
SCERT Maharashtra Question Bank 12th Standard HSC Biology Maharashtra State Board 2022
Chapter 2 Reproduction in Lower and Higher Animals
Short Answer 2 | Q 3
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