Biomedical subjects

M L Kann

Publications and source records attributed to M L Kann.

29 records · Page 2Linked to original sources

PubMed1989

Comparison of LR white resin, Lowicryl K4M and Epon postembedding procedures for immunogold staining of actin in the testis.

The efficiency of various postembedding procedures for actin immunogold detection was compared using testicular tissue as a model. Whatever the fixative, testes embedded in LR White resin or in Lowicryl K4M showed few differences as regard ultrastructural preservation and gave similar actin antigenicity preservation. A purified polyclonal antibody (IgG) and a monoclonal antibody (IgM) visualized with gold secondary antibody yielded high labeling intensity whereas the IgG-protein-A gold association was less efficient. Crude antisera gave a low specific staining/background ratio. Samples of testes, fixed in different conditions, were also embedded in Epon, omitting propylene oxide and lowering polymerization temperature to 40 degrees-50 degrees C. This slight modification improved ultrastructural preservation which was better than with hydrophilic resins, as well as made possible immunogold detection of actin though antigenicity preservation was lesser than with these resins. Thus, in Epon embedded samples actin labeling, using IgG antiactin-gold secondary antibody, was similar to that observed after hydrophilic resin-protein-A gold procedures. In addition to actin labeling of various somatic cells it was confirmed that actin is a consistent component of the subacrosomal space of spermatids during the greater part of spermiogenesis in rat.

Actins↗

PubMed1987

Mitotic activity in monkey and rat Leydig cells.

The testes of the monkey, Macaca fascicularis, from birth to adulthood and of rats from puberty to adulthood were examined by both light and electron microscopy to estimate the mitotic activity of the Leydig cells. In monkeys, mitotic activity was measurable only in neonates: 2.3% in Leydig cells and 0.4% in fibroblast-like cells. From measurements of 3H-thymidine incorporation, mature Leydig cells were labeled in neonates (2%) and adult animals (1%). The labeling indices were significantly increased with increasing time after isotope exposure, and some pairs of labeled cells were found. In prepubertal (28 days of age) and pubertal (45 days of age) rats, mitotic indices were 2 and 0.2%, respectively, in the Leydig cells and 0.4 and 0.1% in fibroblast-like and myoid cells, respectively. Mitoses were not detected in postpubertal rats at 63 days of age. Taken together, these results demonstrate the self-renewal ability of mature Leydig cells during normal development.

Aging↗

PubMed1986

Forward motility protein (FMP): localization in hamster epididymal spermatozoa.

The presence of FMP was investigated by immunocytochemistry in spermatozoa from the hamster caput and cauda epididymis. Spermatozoa from the caput showed no staining whereas spermatozoa pre-incubated with FMP were stained on the acrosome. Pre-treatment of the same sperm with epididymal plasma induced staining on the principal piece of the flagellum. Spermatozoa from the cauda were stained without previous incubation both on the acrosome and on the principal piece of the flagellum. These results suggest that the action of FMP, which prevents head-to-head agglutination of motile spermatozoa and allows acquisition of forward motility, may be due to at least two proteins. The first localizes to the acrosome during epididymal transit (anti-sticking factor), whilst the second localizes to the principal piece of the flagellum (forward motility initiation factor).

Acrosome↗

PubMed1984

Motility induction in hamster spermatozoa from caput epididymidis: effects of forward motility protein (FMP) and calmodulin inhibitor.

The motility characteristics and the behaviour of caput spermatozoa were investigated. After dilution in B2 medium the majority of spermatozoa presented head-to-head agglutination and a twisted flagellum. Only a small population of these spermatozoa developed an anarchic motility pattern. The addition of crude bovine epididymal fluid forward motility protein (FMP) to the incubation medium suppressed flagellar angulation and agglutination. The addition of FMP to caffeine-activated spermatozoa induced a slow-swimming progressive movement in about 10% of the spermatozoa. In order to establish an hypothetical role of FMP in the regulation of calcium transport a calmodulin inhibitor, fluphenazin, was tested. When added to caffeine-activated spermatozoa at a rate of 10(-5) M, it induced about 15% of progressive spermatozoa with flagellar angulations. The trajectories of these spermatozoa were similar to those observed in samples of spermatozoa from the cauda epididymidis. It is concluded that during epididymal maturation a calcium-dependent mechanism might be involved in the transformation of an irregular movement into a progressive movement.

Animals↗

PubMed1982

In vivo fertilization after initiation of sperm motility in the hamster epididymis.

Hamster spermatozoa, collected from the caput and the cauda of the epididymis, are known to differ in their motility. They do not normally acquire fertilizing ability until they reach the proximal portion of the cauda epididymidis. The aim of the present investigation was to test the fertilizing capacity of spermatozoa from the caput epididymis after initiation. Sperm cells were incubated by adding 10 mM caffeine and 20-30 p. 100 epididymal plasma to the culture medium. Superovulated females were inseminated in utero and the eggs recovered 14 h after ovulation. In these conditions, 22 p. 100 of the ova were fertilized. The possibility that the increased motility of the caput epididymal spermatozoa might reflect an increase in fertilizing ability is discussed.

Animals↗

PubMed1980

Development and initiation of sperm motility in the hamster epididymis.

Hamster spermatozoa were isolated from the caput, corpus and cauda epididymidis. They were observed in culture medium at 37 degrees C with a phase-contrast microscope and their motility recorded cinematographically. About 20 p. 100 of the caput epididymidis spermatozoa were motile and moved in a confined space with no forward progression. 30 p. 100 of the corpus epididymidis spermatozoa were motile, showing increased flagellar activity and moving in wide circles. 90 p. 100 of the cauda epididymidis spermatozoa were motile and moved forward. Forward motility was induced in immotile spermatozoa from the caput epididymidis by adding cyclic 3'-5' adenosine monophosphate (cAMP) phosphodiesterase inhibitors (caffeine, theophylline, IMX) and epididymal plasma. The best stimulation was initiated by 15 mM caffeine with 10 p. 100 of cauda epididymal plasma; a mean of 60 p, 100 of forward motility was obtained which lasted for one hour and then ceased. Cinematographic studies revealed that some induced sperm movements differed from the equivalent natural ones by the amplitude of the head movements. It is shown that during epididymal transit of hamster spermatozoa, the induction of forward motility requires not only an increased cAMP level but also factors from the cauda epididymal plasma. The idea that glycoprotein of epididymal origin initiates forward motility is discussed.

1-Methyl-3-isobutylxanthine↗

PubMed1974