ABSTRACT
A midpiece sperm defect with a frequency of 25-35% in ejaculates obtained from a Hereford bull with a 60 d non-return rate of 76.4% after careful pre- and post-freeze semen selection was studied in light microscope and by transmission electron microscopy. The defect consisted in a folding and coiling of the distal midpiece characterized by disorganization and irregularity of mitochondria surrounding the axial fiber bundle, combined with retraction of doublet fibers and dislocation and fracturing of these elements and the corresponding dense fibers. Based on examination of the spermatogenic epithelium it was concluded that the alterations in the axial fiber bundle were secondary to those in the mitochondrial sheath. The abnormality appeared to be related to the "Dag-like" defect earlier observed in different breeds.
Subject(s)
Cryopreservation/veterinary , Semen Preservation/veterinary , Spermatozoa/abnormalities , Animals , Cattle , Ejaculation , Male , Microscopy, Electron , Spermatozoa/cytology , Spermatozoa/ultrastructureABSTRACT
Membrane alterations in bull spermatozoa after freezing and thawing and after the process of in vitro capacitation and fertilization were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Even if the majority of the spermatozoa exhibited intact membranes after freezing and thawing (90%), one could distinguish between 3 types of membrane defects depending of the different structures involved. The first type showed loss of plasmalemma over the entire acrosome. In the second category the anterior part of the outer acrosomal membrane exhibited a pronounced extension, but was covered by a partly intact plasmalemma. The last category consisted of spermatozoa with extensive vesiculation and disruption of plasmalemma and the outer acrosomal membrane. This type of defect could not easily be distinguished from a true acrosome reaction. The cumulus cells showed an active phagocytosis of both intact and acrosome reacted spermatozoa.
Subject(s)
Cryopreservation/veterinary , Fertilization in Vitro , Freezing , Semen Preservation/veterinary , Spermatozoa/ultrastructure , Acrosome/ultrastructure , Animals , Cattle , Cell Membrane/ultrastructure , MaleABSTRACT
Mussels exposed to dinoflagellates may represent a human health risk due to accumulation of a variety of algal toxins. In several parts of the world, algal toxins leading to diarrhea (diarrhetic shellfish poisons, DSP) are found in mussels for extended periods of the year. Routine monitoring of these toxins involves ip injections in mice. Chemical analytical methods have been developed for only some of the toxins in question, namely, those giving diarrhea. Other toxins in the DSP complex are not easily detected by analytical methods. In this report we show that freshly prepared hepatocytes from rats are a convenient means to differentiate between the toxins that give diarrhea and those that do not. Consequently, hepatocytes can be useful in both screening and as a tool in the process of developing analytical methods. Freshly prepared hepatocytes might be useful in combination either with the mouse bioassay or with chemical analytical methods.
Subject(s)
Bacterial Toxins , Liver/drug effects , Marine Toxins/toxicity , Oxocins , Animals , Bivalvia , Cells, Cultured , Cyanobacteria Toxins , Diarrhea/etiology , Dose-Response Relationship, Drug , Ethers, Cyclic/toxicity , L-Lactate Dehydrogenase/metabolism , Liver/cytology , Liver/enzymology , Liver/ultrastructure , Macrolides , Male , Microcystins , Microscopy, Electron, Scanning , Mollusk Venoms/toxicity , Okadaic Acid , Pyrans/toxicity , Rats , ShellfishABSTRACT
Secretin causes the bile duct cells to secrete HCO3-. To examine whether the transformation of duct cell ultrastructure that follows secretin stimulation depends on microtubules and is important for ductular HCO3- secretion, we examined the effect of colchicine on ductular HCO3- secretion and on the morphology of cells lining bile ductules of anaesthetized pigs. Colchicine blocked secretin-dependent cytoplasmic clearance of tubulovesicles and prevented expansion of the basolateral plasma membrane in duct cells and reduced the ductular HCO3- secretory response from 132 +/- 25 mumol min-1 to 97 +/- 14 mumol min-1. In contrast, lumicolchicine did not affect secretin-dependent tubulovesicle clearance or plasma membrane geometry or ductular HCO3- secretion. Accordingly, secretin-dependent cytoplasmic clearance of tubulovesicles in bile duct cells appears to depend on microtubules and to be important for ductular HCO3- secretion.
Subject(s)
Bicarbonates/metabolism , Bile Ducts/drug effects , Colchicine/pharmacology , Microtubules/drug effects , Secretin/physiology , Animals , Bile Ducts/metabolism , Bile Ducts/ultrastructure , Lumicolchicines/pharmacology , Microtubules/metabolism , Microtubules/ultrastructure , SwineABSTRACT
Secretin stimulation clears the cytoplasm of intralobular pancreatic duct cells in pigs of tubulovesicles and causes these cells to secrete HCO3- into the pancreatic juice. To determine whether the clearance of cytoplasmic tubulovesicles involves the microtubule system and is important for initiation of HCO3- secretion, the effect of the microtubule poison colchicine on duct cell morphology and pancreatic HCO3- secretion was measured in anaesthetized pigs. Before colchicine, secretin reduced the density of tubulovesicles in the cytoplasm of pancreatic duct cells from 92 +/- 8 U to 8 +/- 2 U and initiated pancreatic secretion of 176 +/- 21 mumols min-1 HCO3-. After colchicine, secretin failed to lower duct cell tubulovesicle density and caused the secretion of only 77 +/- 14 mumols min-1 HCO3-. By contrast, lumicolchicine, an isomer of colchicine that does not affect microtubules, did not inhibit pancreatic HCO3- secretion. Colchicine did not reduce carbonic anhydrase or Na,K-ATPase activities in in-vitro assays. The clearance of tubulovesicles from the cytoplasm of pancreatic duct cells therefore seems to be microtubule-dependent and important for the pancreatic HCO3- secretion.
