Data/hora: 12/06/2024 04:13:00

Biblioteca(s): 	Embrapa Caprinos e Ovinos.	
Data corrente: 	12/02/1996	
Data da última atualização: 	13/06/2023	
Autoria: 	AMANN, R. P.; HAMMERSTEDT, R. H.; VEERAMACHANENI, D. N. R.	
Título: 	The epididymis and sperm maturation: a perspective.	
Ano de publicação: 	1993	
Fonte/Imprenta: 	Reproduction, Fertility and Development, v. 5, n. 4, p. 361-381, 1993.	
Idioma: 	Inglês	
Conteúdo: 	Abstract: In common mammals, sperm leaving the testis are incapable of fertilizing a female gamete. Sperm have limited biosynthetic capability and need to minimize demand for ATP. Hence, modification of sperm to achieve their maturation requires pre-programmed cleavage of integral molecules (planned self-modification) and remodelling by action of molecules found in the suspending fluids. Most of these biocatalysts are secreted by a series of specialized regions in the epididymal epithelium, but some are provided in seminal plasma. The role of the epididymis in sperm maturation is postulated to be 'setting a series of triggers' each capable of initiating cellular changes either at emission or near or in the oocyte, and 'setting a safety' for each trigger to prevent premature occurrence of the event. The attributes required in a spermatozoon for in vitro fertilization and natural mating are different, and their expression is dependent on the site of sperm sampling. Some attributes needed for fertility are probably like an on-off switch, whereas others probably allow a gradually reduced probability of success before going to the off position (analogous to a conventional light switch and a dimmer-type light switch). All essential attributes of a spermatozoon must be expressed in a 'combined effective amount' for that cell to be fertile. Because of mixing, in any segment of the epididymal duct the population of sperm is heterogeneous in age and biological status. Thus, when assessing sperm maturation it is necessary to establish the proportion of sperm that has completed and retained all steps of maturation necessary to achieve fertilization of oocytes under the conditions imposed. In a normal animal, most sperm leaving the epididymis have a 'combined effective amount' of attributes, and the population has a high fertilizing potential.	
Palavras-Chave: 	Maturacao espermatica.	
Thesagro: 	Fisiologia; Reprodução; Sêmen.	
Thesaurus Nal: 	Epididymis; Reproduction; Spermatozoa.	
Categoria do assunto: 	L Ciência Animal e Produtos de Origem Animal	
Registro original: 	Embrapa Caprinos e Ovinos (CNPC)	
Exemplares: 	CNPC - (8314-1) - ADD - AP - DD -  -  -  - DIS