Spinnbarkeit (), also known as fibrosity, is a biomedical
rheology
Rheology (; ) is the study of the flow of matter, primarily in a fluid (liquid or gas) state but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applie ...
term which refers to the stringy or stretchy property found to varying degrees in
mucus
Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...
,
saliva
Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...
,
albumen
Egg white is the clear liquid (also called the albumen or the glair/glaire) contained within an egg. In chickens, it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms aro ...
and similar
viscoelastic
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ...
fluids. The term is used especially with reference to
cervical mucus
The cervix (: cervices) or cervix uteri is a dynamic fibromuscular sexual organ of the female reproductive system that connects the vagina with the uterine cavity. The human female cervix has been documented anatomically since at least the tim ...
at the time just prior to or during
ovulation
Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...
.

Under the influence of
estrogens, cervical mucus becomes abundant, clear, and stretchable, and somewhat like egg white. The stretchability of the mucus is described by its spinnbarkeit, from the
German word for the ''
ability to be spun''. Only such mucus appears to be able to be penetrated by
sperm
Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...
. After ovulation, the character of cervical mucus changes, and under the influence of
progesterone
Progesterone (; P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the ma ...
it becomes thick, scant, and tacky. Sperm typically cannot penetrate it.
Saliva
Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...
does not always exhibit spinnbarkeit, but it can under certain circumstances. The thickness and spinnbarkeit of nasal mucus are factors in whether or not the nose seems to be blocked.
Mucociliary transport depends on the interaction of fibrous mucus with beating cilia.
See also
*
Mucorrhea
References
Gynaecology
Medical terminology
German words and phrases
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