Abstract

FILIPIAK, Y; VIQUEIRA, M  and  BIELLI, A. Development and follicular dynamics from fetal life until puberty in cattle. Veterinaria (Montev.) [online]. 2016, vol.52, n.202, pp.2-2. ISSN 0376-4362.

Summary We review the follicular development and follicular dynamics from a histological and developmental perspective, from fetal to prepubertal life in cattle (Bos taurus). This is a complex and coordinated process accompanied by physiological and morphological changes involved in oocyte differentiation and development. The ovarian follicles are the fundamental unit of the ovary and command both reproductive processes and the phases of the estrous cycle, with two main functions, production of hormones and of oocytes. The formation of primordial follicles is a process called follicular assembly, whereby "nests" of oocytes complete their mitotic proliferation and enter meiosis, while many of such follicles become apoptotic, promoting the disruption of oocyte nests. The formation process of primordial follicles begins during fetal development in cattle, approximately at 80 days of gestation. There is considerable individual variation in the number of follicles, and there is a pool of reserve follicles built before birth. Cow’s ovaries hold about 2,700,000 primordial follicles, but 90% degenerate, with approximately 135,000 germ cells surviving at birth and declining promptly until puberty and even later in life. Primordial follicles develop into primary, secondary, antral and preovulatory follicles (in adults). This developmental process involves cytological, histological and morphological changes. In calves, follicular waves similar to those in adult animals occur from 2 weeks of age on. Important endocrine and ovarian changes are observed at puberty and are influenced by multiple factors. Follicular development is closely linked to the future reproductive performance of females. Thus, knowing this process is essential in order to manage adequately cattle breeding as well as to deepen research regarding this subject

Keywords : follicular development; follicles; oocytes; follicular dynamics; bovine cattle.

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