Recent advances and new concepts on follicle and endocrine dynamics during the equine periovulatory period
Animal Reproduction
Recent advances and new concepts on follicle and endocrine dynamics during the equine periovulatory period
Autor Correspondente: E L Gastal | [email protected]
Palavras-chave: follicles, gonadotropins, mares, ovarian steroids, ovulation
Resumos Cadastrados
Resumo Inglês:
During the recent years, mares have been
shown as relevant follicle-related research comparative
model for women because of similarities in the number
and nature of ovarian follicular waves, a constant
relative diameter of the largest follicle between the two
species at definable events throughout the ovulatory
wave, and similar ultrasonographic characteristics and
changes of the preovulatory follicle. In the mare, as in
other monovular species (cattle, women), usually only
one dominant follicle develops as a result of the
deviation mechanism. However, occasionally two or
more dominant follicles may also occur. Few studies in
mares have addressed the relationships between
periovulatory circulating hormone concentrations and
single versus multiple dominant/preovulatory follicles.
Temporal and mechanistic studies performed recently
(years 2005 to 2008) have contributed to elucidation of
intriguing relationships among the dominant follicle and
circulating hormones and will be the focus of this
review. The main topics discussed herein are: (i)
development of one versus two dominant follicles with
a single ovulation; (ii) development of one versus
multiple ovulatory follicles; (iii) conversion of two
dominant follicles to double ovulations; (iv) role of
hormones in development of double ovulations; (v)
interrelationships of periovulatory reproductive hormones;
(vi) repeatability of preovulatory follicle diameter and
hormones; and (vii) factors that affect preovulatory
follicle diameter and hormones, such as breeds and types
of mares, season, body condition, and aging.
