Progress in understanding ovarian follicular dynamics in cattle.
نویسندگان
چکیده
The study of follicular dynamics began in the mid-20th century, but progress has been particularly rapid in the last two decades through the use of tools that have enabled serial, non-invasive examination. A brief overview of early oogenesis and folliculogenesis is provided as a backdrop to the evolution of our understanding of follicular dynamics during the bovine estrous cycle. Studies to date support the concept that the pair of ovaries acts as a single unit and influences follicular development primarily via systemic endocrine routes involving ovarian and uterine products, the gonadotropins, and their receptors. Dominant and subordinate follicles pass through growing, static and regressing phases that have distinct morphologic and biochemical characteristics; these changes are the basis of efforts focused on diagnosing and manipulating follicular status. An update of research progress highlights recent findings on the repeatability (predictability) within individuals of follicle recruitment and wave pattern (two- versus three-wave cycles), the relationship between oocyte competence and follicular status, and the dynamics of small follicles. Recent studies documented that wave emergence and follicular dominance are apparent earlier than previously reported, and on the basis of periodic endogenous FSH surges and the presence of FSH receptors, the hypothesis that follicles become progressively entrained to waves from the earliest stages of development is introduced. Lastly, recent studies comparing old cows and their young daughters provide a new understanding of the effects of aging on gonadotropins and ovarian steroids, follicular dynamics, ovarian response to synchronization, superstimulation, and oocyte competence.
منابع مشابه
Hormonal Profile of Ovarian Follicular Fluid and Blood Plasma during Different Stages of Estrous Cycle in Holstein Cattle
The aim of this study was to evaluate the concentrations of reproductive hormones in blood plasma and in follicular fluids of different sized follicles during various stages of the estrous cycle in Holstein cattle. Jugular blood samples from 42 adult Holstein cattle were collected immediately after the slaughter. Antral fluids from small (4-5 mm), medium (6-9 mm) and large (10-20 mm) follicles ...
متن کاملEffect of Metabolic Stress on Ovarian Activity and Reproductive Performance of Dairy Cattle: A Review
Reproductive efficiency in dairy cattle has been decreased over the last 5 decades despite significant gains in genetic selection, improved reproductive technologies and nutritional care. In high-yielding dairy cattle, the negative energy balance (NEB) during the first week post-partum adversely affects ovarian activity, mainly follicle growth and steroidogenesis. Circulating levels of non-este...
متن کاملOvarian follicular dynamics during estrous cycle and its aberrations during certain reproductive disorders in buffalo
Ovarian follicular development in the species follows a wave dynamics involving mostly 2wave or 3-wave cycles. Although there are still large gaps in our understanding of the etiopathogenic mechanisms underlying reproductive disorders in buffalo, available literature suggests alterations in ovarian dynamics at one or more stages of follicular development. This article gives a brief account of t...
متن کاملEffect of Administration of an Opioid Antagonist (Naloxane) to Treat Ovarian Cysts in Dairy Cows
The role of stress in the pathogenesis of ovarian cysts is believed to be mediated by the discharge of endogenous cortisol, which inhibits LH release. Endogenous opioid peptides are involved in many responses to stress. Therefore, the aim of this study was to determine the effect of epidural administration of Naloxone (NX) on cystic regression and follicle development leading to normal oestrus ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Theriogenology
دوره 69 1 شماره
صفحات -
تاریخ انتشار 2008