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Vagusstoff (literally translated from German as "Vagus Substance") refers to the substance released by stimulation of the vagus nerve which causes a reduction in the heart rate. Discovered in 1921 by physiologist Otto Loewi , vagusstoff was the first confirmation of chemical synaptic transmission and the first neurotransmitter ever discovered.
The female is not yet sexually receptive; the old corpus luteum degenerates; the uterus and the vagina distend and fill with fluid, become contractile and secrete a sanguinous fluid; the vaginal epithelium proliferates and the vaginal cytology shows a large number of non-cornified nucleated epithelial cells.
From birth, the ovaries of the human female contain many immature, primordial follicles. These follicles each contain a similarly immature primary oocyte . At puberty , clutches of follicles begin folliculogenesis, entering a growth pattern that ends in ovulation (the process where the oocyte leaves the follicle) or in atresia (death of the ...
Evolution of sexual reproduction describes how sexually reproducing animals, plants, fungi and protists could have evolved from a common ancestor that was a single-celled eukaryotic species.
Kittens are categorized in a growth life stage, and have high energy and protein requirements. [23] When feeding a kitten, it is often recommended to use highly digestible ingredients and various components to aid in development in order to produce a healthy adult. [ 24 ]
Crucial to this doctrine are the ideas that life comes from non-life and that no causal agent, such as a parent, is needed. Supposed examples included the seasonal generation of mice and other animals from the mud of the Nile , the emergence of fleas from inanimate matter such as dust, or the appearance of maggots in dead flesh.
In the female, a deep groove forms around the phallus. The sides of it grow dorsalward as the labioscrotal folds, which ultimately form the labia majora in females. The labia minora, in contrast, arise by the continued growth of the lips of the groove on the under surface of the phallus; the remainder of the phallus forms the clitoral glans. [8]
Fever coat is an effect known in domestic cats, where a pregnant female cat has a fever or is stressed, causing her unborn kittens' fur to develop a silver-type color (silver-grey, cream, or reddish) rather than what the kitten's genetics would normally cause. After birth, over some weeks the silver fur is replaced naturally by fur colors ...