The theca externa is the outer layer of the
theca folliculi. It is derived from connective tissue, the cells resembling
fibroblasts, and contains abundant
collagen.
During ovulation, the surge in
luteinizing hormone
Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
increases
cAMP
Camp may refer to:
Outdoor accommodation and recreation
* Campsite or campground, a recreational outdoor sleeping and eating site
* a temporary settlement for nomads
* Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...
which increases
progesterone and
PGF2α production. The PGF2α induces the contraction of the
smooth muscle cells of the theca externa, increasing intrafollicular pressure. This aids in rupture of the mature
oocyte
An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The femal ...
, or immature oocyte at the germinal vesicle stage in the canine, along with
plasmin
Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is encode ...
and
collagenase
Collagenases are enzymes that break the peptide bonds in collagen. They assist in destroying extracellular structures in the pathogenesis of bacteria such as ''Clostridium''. They are considered a virulence factor, facilitating the spread of ...
degradation of the follicle wall.
References
External links
*
* - "Mammal, canine ovary (LM, High)"
* - "Mammal, bovine ovary (LM, Medium)"
* - externa
*
Slide at trinity.edu
Mammal female reproductive system
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