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Even within species significant variability can be observed, thus cats may undergo an estrous cycle of 3 to 7 weeks. [15] Domestication can affect estrous cycles due to changes in the environment. For most species, vaginal smear cytology may be used in order to identify estrous cycle phases and durations. [16]
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
The second signal is released during the ovulatory phase of the estrous cycle and it lengthens estrous cycles. When rats live together or share the same air supply, the pheromones released by each female in a group as a function of the phase of her estrous cycle causes other females in the group to either lengthen or shorten their estrous cycles.
Diagram illustrating how the uterus lining builds up and breaks down during the menstrual cycle Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone ...
Follicular phase diagram of hormones and their origins Follicle-stimulating hormone (FSH) is secreted by the anterior pituitary gland (Figure 2). FSH secretion begins to rise in the last few days of the previous menstrual cycle, [ 3 ] and is the highest and most important during the first week of the follicular phase [ 4 ] (Figure 1).
A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. [1] [2] In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: Blood pressure. Aortic ...
Overt menstruation (where there is blood flow from the vagina) occurs primarily in humans and close evolutionary relatives such as chimpanzees. [7] Some species, such as domestic dogs , experience small amounts of vaginal bleeding while approaching heat; [ 12 ] this discharge has a different physiologic cause than menstruation.
As the cycle progresses to the luteal phase, inhibin A becomes the primary form produced by the corpus luteum. The declining steroid production by the corpus luteum and the dramatic fall of inhibin A towards the end of the luteal phase allow for FSH to rise during the last few days of the menstrual cycle.