Follicle

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Related to primordial follicle: Graafian follicle, ovulation, zona pellucida, primary oocyte

follicle

[′fäl·ə·kəl]
(biology)
A deep, narrow sheath or a small cavity.
(botany)
A type of dehiscent fruit composed of one carpel opening along a single suture.

Follicle

 

a dry, one-celled, many-seeded, and monocarpel-lary fruit that opens along a ventral suture. The seeds are located along the suture on the edges of the carpel. Follicles are typical of the magnolias; of such members of Ranunculaceae as cowslip, garden columbine, aconite and larkspur; and of some genera of Rosaceae, such as Physocarpus.

The simplest follicles resemble a leaf folded in half lengthwise; the upper part corresponds to a stigma and the stem to a stalk. A large number of follicles may be positioned in a spiral on the axis of a blossom (as in the magnolia) to form a multiple fruit. Other types of fruits developed from follicles: nuts are follicles with a single seed, and beans are follicles with a different form of opening.


Follicle

 

a round, oval, or pear-shaped anatomical structure present in various organs in man and other vertebrates, having varied functions. In mammals egg cells develop within the ovarian follicle, which consists of a group of cells; one of these is the egg cell and the rest are epithelial cells surrounding the egg, first in one layer and then in several. As the follicle matures, spaces between the cells become filled with a clear liquid, and the single-layered primordial follicle is transformed into a mature multi-layered follicle, the Graafian follicle.

The follicle of the thyroid gland secretes thyroglobulin, a precursor of the thyroid hormones. Into the hair follicles, which enclose the hair roots and bulbs, empty excretory ducts of the sebaceous glands. Many lymphatic follicles are located in the mucous membranes of the digestive tract, the respiratory tract, and the urinary tract; for instance, follicles known as peyer’s patches are situated in the mucous membrane layer of the intestine.

References in periodicals archive ?
Its lack leads to accelerated loss of postnatal primordial follicles in mice(33).
The mean number of primordial follicles was close to that of primary follicles, in contrast to what is generally observed in mammals.
The primordial follicles were defined as an oocyte encapsulated by squamose pregranulosa cells, primary follicles as those with one layer of cuboidal granulosa cells and preantral follicles as those with two and more layers of cuboidal granulosa cells.
Results show that the number of primordial follicles following exposure to cyclophosphamide was significantly reduced (36.
The number of primordial follicles was determined using an optical disector design applied to 25 |m thick sections.
Despite multiple approaches to estimating OR with accuracy, direct assessment of primordial follicle pool that truly constitutes the reserve is considered as the best technique.
Primordial follicle ultrastructure: In primordial follicles, oocytes were surrounded by 4-8 flattened granulosa cells and it had shown a homogenous cytoplasm with a large number of vesicle and centrally located nucleus.
Bone morphogenic protein 4 (BMP4) as a follicle survival factor can promote primordial follicle development (Nilsson and Skinner, 2003).