Theca externa
The theca externa is the outer layer of the theca folliculi , a band of connective tissue that surrounds the follicle in the ovary at an advanced stage of maturity. The theca externa arises in the stage of the tertiary follicle , where the connective tissue border differentiates into the theca externa and the theca interna . The theca externa consists of connective tissue , the cells of which are like fibroblasts , and contains large amounts of collagen . During ovulation , the rise in luteinizing hormone (LH) causes an increase in cyclic adenosine monophosphate (cAMP), which in turn increases the production of progesterone and prostaglandin F2α (PGF2α). The PGF2α triggers the contraction of the fine muscle cells of the theca externa and thereby increases the intrafollicular pressure. This supports the detachment of the mature egg cell, or - in dogs - the immature egg cell in the germinal vesicle stage , together with a breakdown of the plasmin and the collagenase of the follicle wall.
Individual evidence
- ↑ TW Sadler: Langmans embryologi . 2nd Edition. Munksgaard Danmark, Copenhagen 2008, ISBN 978-87-628-0508-8 .
