Search results
Results From The WOW.Com Content Network
The epididymis secretes immobilin, a large glycoprotein that is responsible for the creating of the viscoelastic luminal environment that serves to mechanically immobilize spermatozoa until ejaculation. Immobilin is predominantly secreted into the proximal caput epididymidis prior to the acquisition of the potential for sperm motility.
Besides expressing factors that are crucial for sperm cell maturation, Sertoli cells also produce a wide range of molecules (either on their surface or soluble) that are able to modify the immune system. The ability of Sertoli cells to change the immune response in the tubule is needed for successful sperm cell maturation.
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]
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]
Cells present in the testes express molecules that play key roles in the regulation of SSC self-renewal. In mice, Sertoli cells have been shown to secrete Glial cell line-derived neurotrophic factor (GDNF) which has a stimulatory effect on stem cell self-renewal. This factor is thought to be expressed in the peritubular cells in human testes. [4]
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.