Showing papers on "Sperm plasma membrane published in 1967"

Effects of duct ligation on the fertilzing ability of spermatozoa from different regions of the rabbit epididymis

Abstract: In the normal rabbit, fertile spermatozoa first appear in the lower half of the corpus epididymidis. If sperm passage is impeded in the low corpus region, the capacity to fertilize and initiate normal ovum development can ultimately arise in sperm withheld in any part of the ductus epididymidis, distal to the caput flexure. Sperm released from the initial part of the epididymis proximal to the caput flexure did not fertilize, even though many showed apparently normal progressive motility twelve and one-half to fifteen days after low corporeal ligation. Since these infertile, motile sperm did not show the normal head–head agglutination reaction of mature rabbit sperm in a medium containing serum, it appears that the dichotomy between motility and fertilizing ability may have been at least partly due to the persistence in an immature state of the sperm plasma membrane. Many caput sperm which displayed normal sustained motility had retained the cytoplasmic droplet in the neck region, whereas, in others showing comparable motility, the droplet had moved along the midpiece or had been lost. It, therefore, seems unlikely that movement and loss of the droplet can be of importance in development of the capacity for motility in maturing spermatozoa.

Acrosome Reaction and Lysins

Abstract: Publisher Summary This chapter discusses the acrosome reaction and lysins. The concept of the acrosome reaction had its origin in phase-contrast microscopic observations of living spermatozoa fixed with formaldehyde under various experimental conditions. It is generally found that the acrosome undergoes change when the spermatozoon swims in to contact with the protective covering surrounding the egg in invertebrates. The primary requisite for acrosomal reactivity is a good physiological condition of the spermatozoon. Evidence that excessive alkalinity damages the cell surface suggests that the acrosome-stimulating effect of the mildly alkaline medium may have a direct connection with the state of the sperm plasma membrane.

Membrane Fusion in Relation to Sperm-Egg Association

Abstract: Publisher Summary This chapter describes the relationship between membrane fusion and sperm–egg association. At the inception of the zygote, the external rather than the cytoplasmic sides of the plasma membranes are the first to be involved. In species with vitelline envelopes, the meeting of plasma membranes takes place beneath the envelope so that a part of the egg plasma membrane that meets the sperm plasma membrane is in a sense also a newly exposed surface. However, in algae, the gametes are recently shed cells so that both membranes are newly exposed ones. The parts of the plasma membrane that begin the fusion are newly exposed exterior surfaces. As a result of the fusion, the content of the vesicle is conducted out of the cell without coming in contact with the cytoplasm.