Follicle

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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 ?
An LH surge at cycle day 14 stimulates ovulation by causing the dominant follicle to burst and release its egg.
Furthermore, the dominant follicle selection occurred at 48 after follicular ablation and there was a significant difference in diameter of F1, F2 and F3 (p<0.
These results support the idea that the dominant follicle can inhibit the growth of smaller follicles as suggested by studies with heifers (Matton et al.
The women on the continuous regimen had no dominant follicles and no ovulations.
The proposed quantity varies among authors and ranges from less than three to less than five dominant follicles on the day of hCG administration noted on ultrasound and/or less than three to less than five retrieved oocytes (6-11).
In contrast, mean LH levels and LH pulse frequency increased in the treated subjects after 2 weeks, while maximal follicular diameter, the number of dominant follicles, ovarian volume, and estradiol levels increased over 3 months.