Ovarian cycles

McClintock M. (1983). Pheromomal regulation of the ovarian cycle enhancement, suppression and synchrony. In Pheromones and Reproduction in Mammals (Vandenberg J.G., ed.). Academic Press, New York, pp. 113-150. 

The human female reproductive (ovarian) cycle is initiated and regulated by gonadotrophic hormones. Day 1 of the cycle is characterized by commencement of menstruation the discharge of fragments of the endometrium (wall of the womb) from the body, signifying fertilization has not occurred in the last cycle. At this stage, plasma levels of FSH and LH are low, but these begin to increase slowly over the subsequent 10-14 days. 

Schank, J. C. and McClintock, M. K. (1997) Ovulatory pheromone shortens ovarian cycles of female rats living in olfactory isolation. Physiol. Behav. 62, 899-904. 

Advantages and Disadvantages. Advantages of using monkeys in safety assessment studies include their phylogenetic proximity, as well as their physiological, behavioral, and, often, metabolic similarities, to humans (Table 16.13). An example is the similarity between the ovarian cycle of female monkeys and women (Mazue and Richez, 1982), which makes the monkey the ideal animal model for reproductive studies. Another advantage associated with most species of monkeys used in safety assessment studies is that they are much smaller than nonrodents such as the dog and, thus like the ferret, require less test compound. 

Mice are able actively to seek or avoid priming pheromones that modulate their ovarian cycle and onset of puberty. Peripubertal female mice avoid the urine odor of adult males, known to accelerate puberty in females, and are more attracted to the odor of grouped adult females. This behavior is particularly effective because the active space of the (almost) non-volatile male pheromone is small, and prolonged exposure is required for the effect to occur (Coppola and O Connell, 1988). Likewise, prepubertal female mice do not urinate near urine marks of adult males, while grouped, estrous, and diestrous adult females do. Such behavior may help young females to avoid exposure to male odors until they reach puberty. This way they would be protected from mating too early, and their eventual reproductive success would be enhanced (Drickamer, 1989a). 

Olfactoiy thresholds also vary with the ovarian cycle. Women are most sensitive to odors around the time of ovulation, when estrogen levels are highest, and less sensitive to odors during menstruation. This may have sensory-physiological reasons. During menstruation the mucus layer on the olfactory epithelium is thicker and more likely to trap molecules, while the thin mucus layer at the time of ovulation renders the receptors more accessible. The thickness of the mucus layer, in turn, is controlled by testosterone and estrogen (Mair etal, 1978). 

Most goats in the northern hemisphere breed in fall and winter. Decreasing day length stimulates ovarian cycles. In addition to photoperiod, male pheromones stimulate pulse frequency of LH in the blood plasma of females (Martin etal., 1986). This not only enhances the seasonal onset of ovarian function, but also synchronizes breeding and subsequent lambing. 

Handlin f of females for ovarian cycle monitorinjy Animals are run through a catch tunnel system and vaginal swabs are collected daily. After 2 weeks the animals are familiar with the procedure and many females present their genital region voluntarily once they are separated. 

Selected reaction monitoring is extremely selective for the analyte of interest. An example is provided by the analysis of human estrogens in sewage at parts per trillion levels (ng/L). Estrogens are hormones in the ovarian cycle. The synthetic estrogen 17a-ethinylestradiol (designated EE2) is a contraceptive. Even at parts per trillion levels, some estrogens can provoke reproductive disturbances in fish. 

Unsworth WP, Taylor J A, Robinson JE. Prenatal programming of reproductive neuroendocrine function the effect of prenatal androgens on the development of estrogen positive feedback and ovarian cycles in the ewe. BiolReprod. 2005 72 619-627. 

Over a 7- to 12-day course of daily hMG or urofollitropin administration (intended to mimic the follicular phase of the ovarian cycle in women with hypothalamic amenorrhea), FSH levels gradually rise to twice their baseline level. LH levels increase to 1.5 times their baseline with hMG, but they do not rise with urofollitropin. 

Development of sexual behavior can be affected by neonatal pharmacological treatment with the monoamine oxidase inhibitor pargyline, the monoamine depletor reserpine as well as with the acetylcholine esterase inhibitor pyridostigmine. These results suggest that biogenic amines are involved in sexual differentiation of the brain (refs. 162, 163). Pargyline treatment from day 1 to 14 or day 15 to 28 resulted in earlier development of puberty in female rats and delayed appearance of puberty in male rats. Male sexual behavior was decreased in both sexes. Treatment with reserpine on days 1, 4, 7 and 10 delayed the manifestation of puberty in both sexes, and caused disturbed female ovarian cycles and decreased male mounting behavior. 

Chiang A.-S. and Schal C. (1994) Cyclic volumetric changes in corpus allatum cells in relation to juvenile hormone biosynthesis during ovarian cycles in cockroaches. Arch. Insect Biochem. Physiol. 27, 53-64. 

Maguire, J. L., Stell, B. M., Rafizadeh, M., and Mody, 1. (2005). Ovarian cycle-linked changes in GABA(A) receptors mediating tonic inhibition alter seizure susceptibility and anxiety. Nat. Neurosci. 

The influence of the ovarian cycle on protease activity in the vagina has also been demonstrated. For example, the trypsin-like activity in rat vaginal smears was found to be maximal at proestrus. The activity of //-glucuronidase, acid phosphatase, alkaline phosphatase, and esterase all vary in the vaginal tissue of premenopausal and postmenopausal women. 

Hearn JP,Lunn SF.The endocrinology of the ovarian cycle and of pregnancy in the marmoset monkey, Callithrix jaccus. J Endocrinol 1975 65(3) 1P. 

Gilchrist RB, Wicherek M, Heistermann M, Nayudu PL, Hodges JK. Changes in follicle-stimulating hormone and follicle populations during the ovarian cycle of the common marmoset. Biol Reprod 2001 64(l) 127-35. 

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