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Characteristics of Ovarian Follicle Development in Domestic Animals
Author(s) -
Evans ACO
Publication year - 2003
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1046/j.1439-0531.2003.00439.x
Subject(s) - follicle , biology , follicular phase , ovulation , folliculogenesis , ovarian follicle , litter , estrous cycle , luteal phase , andrology , atresia , endocrinology , medicine , anatomy , pregnancy , ecology , lactation , hormone , genetics
Contents In most domestic animals the later stages of follicle development occurs in a wave‐like pattern during oestrous cycles (cattle, sheep, goats, horses and buffalo) or periods of reproductive activity (llamas and camels). A follicle wave is the organized development of a cohort of gonadotrophin‐dependent follicles all of which initially increase in size, but most of which subsequently regress and die by atresia (subordinate follicles). The number of remaining (dominant) follicles is specific to the species and is indicative of litter size. Follicle waves develop during both luteal and follicular phases and it is the dominant follicle(s) of the last follicular wave that ovulates. However, there are cases where dominant follicles from the last two follicle waves can ovulate (sheep and goats). There are exceptions to the organized wave‐like pattern of follicle growth where follicle development is apparently continuous (pigs and chickens). In these animals many follicles develop to intermediate diameters and at specific times follicles that are destined to ovulate are selected from this pool and continue growing to ovulation. Understanding the pattern of follicle development in different species is increasingly important for designing improved methods to manipulate reproduction in domestic animals.