Estrusion Processes

The effects of atrazine on the reproductive aging processes observed in female SD rats are not relevant to humans. In women, reproductive senescence is characterized principally as an ovarian failure with a decrease in endogenous estrogen exposure at menopause, not the increase that is characteristic of the female SD rat in a state of persistent estrus. 

Bovine estrus synchronization is an important field for the veterinary pharmaceutical industry. A description of the natural bovine cycle and methods to cycle control are presented. In addition, commercially available silicone devices for bovine estrus synchronization are listed. The mathematical modeling of progestagens release from such devices is a crucial tool in the development of novel and/ or optimized delivery systems. For this purpose, several in vitro models, approaches to explain the ADME processes and overall models are described. This type of mathematical modeling could help in the future to customize drug delivery systems to specific animals and/ or situations. 

As presented in Table 15.2, the estrous cycle in cows lasts between 17 and 24 days. This cycle is a dynamic process. The growth and development of follicles and the corpus luteum are regulated by changes in the secretion and patterns of different hormones [16]. The cycle can be divided into four periods estrus, metestrus, diestrus, and proestrus (Figure 15.1) [14, 28]. The estrus and proestrus form the follicular phase which is characterized by the presence of growing follicles. The metestrus and diestrus form the luteal phase in which the presence of a corpus luteum is the most relevant phenomenon. 

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