Ansc431%20Sperm%20transfer%20note%20070 - Sperm Transfer...

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Sperm Transfer Yao ASCI 431 Advanced Reproductive Biology Lecturer: Humphrey Yao [email protected] Topic: Sperm Transfer and Accessory Glands Testis -> Seminiferious tubes -> Spermatogenesis -> Spermatozoa -> Epididymis - > Vas deferens -> Accessory glands -> Urethra (penis) -> Ejaculates -> Vagina -> Cervix -> Uterus -> Oviduct -> egg -> fertilization Male Reproductive Tract I. Epididymis The epididymis is an evolutionary innovation of vertebrates which functions in: 1 transport of spermatozoa from the vas efferentia to the vas deferens, 2 concentration of spermatozoa, 3 maturation of spermatozoa, 4 storage of spermatozoa and 5 secretion of energy substrates and materials coating spermatozoa. The epididymis is rudimentary or absent in fish, amphibians and some reptiles. In some amphibians and reptiles, spermatozoa are stored and matured in an ampulla or large central canal of the testis. It is in mammals with external testis that the most extensive development of the epididymis has occurred. The mammalian male has reorganized the Wolffian duct into the vas efferentia, epididymis and vas deferens. To form the epididymis, the Wolffian duct enlarges and develops a functional epithelium that will be competent to mature spermatozoa under androgen control. A. Structure of Epididymis (Slide 1-2) The epididymis is a single convoluted tubule extending from the vas efferentia to the vas deferens. It is surrounded by smooth muscle and lined with a tall columnar epithelium. The epithelium is made of principal and basal cells. The principle cells have stereocilia or a brush border. The basal cells are apical to the lumen and often have a clear cytoplasm. The numbers of basal cells changes with the segment observed. The epithelium is dependent on testosterone for its function and maintenance. The cell types and physiological activity of the epididymis in sperm maturation, concentration and storage are different in successive segments. Therefore, it is usually divided into three anatomical areas called the caput (head), corpus (body), and cauda (tail). It takes about 9-13 d for the sperm to pass through epididymis depending on species. Caput (Head) Not motile - swim in circular motion Not fertile Page 1 of 6
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Sperm Transfer Yao Proximal droplet Low disulfide linkage Fluid absorption Corpus (Body) First see some forward motility in body Some fertility Droplet moving down More disulfide linkage Binds oocytes Cauda (Tail) Normal motility Fertile Distal droplet High disulfide linkage Binds oocytes B. Functions of the Epididymis (Slide 1-2) i. Maturation of Spermatozoa Spermatozoa recovered from the rete testes, vas efferentia or early caput epididymis are live but infertile and without coordinated motility. They are fertile and capable of motility when recovered from the lower corpus or cauda epididymis. Sperm will mature in isolated segments of the epididymis but only if they have passed through the caput first. Some of the maturation changes occurring in spermatozoa during epididymal
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This note was uploaded on 04/10/2008 for the course ANSC 431 taught by Professor Bahr during the Spring '07 term at University of Illinois at Urbana–Champaign.

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Ansc431%20Sperm%20transfer%20note%20070 - Sperm Transfer...

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