Female sperm storage .January 13, 2021
Female sperm storage is a biological process and often a type of sexual selection in which sperm cells transferred to a female during mating are temporarily retained within a specific part of the reproductive tract before the oocyte, or egg, is fertilized. The site of storage is variable among different animal taxa and ranges from structures that appear to function solely for sperm retention, such as insect spermatheca and bird sperm storage tubules (bird anatomy), to more general regions of the reproductive tract enriched with receptors to which sperm associate before fertilization, such as the caudal portion of the cow oviduct containing sperm-associating annexins. Female sperm storage is an integral stage in the reproductive process for many animals with internal fertilization. It has several documented biological functions including.
Female muscular contractions :
Muscle contraction as a means of moving spermatozoa through the reproductive system into and out of the storage structures has been examined in Diptera, Orthoptera, and Lepidoptera as well as in the species Rhodnius prolixus and the boll weevil. In R. prolixus, rhythmic peristaltic contractions of the oviduct cause contractions of the bursa copulatrix and spermatheca movement. This movement of the spermatheca results in spermatozoa migration into the spermathecal duct and into the spermatheca reservoi.
Female insect nervous system :
The female insect nervous system affects many of the processes involved in sperm storage. The nervous system may signal for muscular contractions, fluid absorption, and hormone release, all of which aid in moving the sperm into the storage organs. When the nervous system of female fruit flies (Drosophila melanogaster) was replaced with a masculinized nervous system through genetic manipulation, sperm storage was affected suggesting that the female nervous system is unique and required to store sperm properly.
Sperm storage organs in the fruit fly Drosophila melanogaster. Female was first mated with GFP-male and then re-mated with RFP-male.
The nervous system is responsible for several fertilization methods. In the migratory locust (Locusta migratoria), the presence of an egg in the genital chamber results in an increase of spermathecal contractions. As a result, sperm is released to fertilize the egg. A neural loop (from the VIIIth ganglion through the N2B nerve to N2B2, N2B3, N2B4, and N2B6b nerves) is then activated to direct the sperm to fertilize the egg via muscular contractions. In the Caribbean fruit fly (Anastrepha suspensa), both the spermathecae and their ducts are innervated by an abdominal ganglion located under the first abdominal sternite. This location suggests that the sperm receptacle can compress and influence the amount of sperm taken in or released by the female fly.