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The epididymis is present in male reptiles, birds, mammals, and cartilaginous fish. [1] The caput epididymidis is fused to the testis in eutherian mammals, but not in marsupials. [13] In reptiles, there is an additional canal between the testis and the head of the epididymis and which receives the various efferent ducts.
Significantly, the low intra-abdominal sperm storage capacity of the echidna epididymis [2] [18] helped inform the role of the epididymis as a prime mover in the evolution of descended testes in mammals whereby lower extra-gonadal temperatures within the scrotal cauda epididymis reduces oxidative respiration of sperm, which enhances oxygen ...
Large molecules cannot pass from the blood into the lumen of a seminiferous tubule due to the presence of tight junctions between adjacent Sertoli cells. [13] The spermatogonia occupy the basal compartment (deep to the level of the tight junctions) and the more mature forms, such as primary and secondary spermatocytes and spermatids, occupy the ...
The epididymis is a long whitish mass of tightly coiled tube. The sperm that are produced in the seminiferous tubules flow into the epididymis. During passage via the epididymis, the sperm undergo maturation and are concentrated by the action of ion channels located on the apical membrane of the epididymis. [2]
Collectively, both superoxide and hydrogen peroxide generated in this process are considered as mitochondrial ROS. [ 1 ] Once thought as merely the by-products of cellular metabolism, mitochondrial ROS are increasingly viewed as important signaling molecules, [ 4 ] whose levels of generation at 11 currently-identified sites vary depending on ...
In humans and other large mammals, there are approximately 15 to 20 efferent ducts, which also occupy nearly one-third of the head of the epididymis. b) single entry, as seen in most small animals such as rodents, whereby the 3–6 ductules merge into a single small ductule before entering the epididymis. [citation needed]
Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom ...
The flowers of flowering plants produce pollen and egg cells, but the sex organs themselves are inside the gametophytes within the pollen and the ovule. [6] Coniferous plants likewise produce their sexually reproductive structures within the gametophytes contained within the cones and pollen. The cones and pollen are not themselves sexual organs.