Ventilation shaft construction by conventional freezing method in Maddhapara Granite Mine, Bangladesh

The aim of this study was to compare pregnancy rates after transfer of in vivo produced embryos cryopreserved using open pulled straw (OPS) vitrification (Group V) or conventional freezing method as a control (Group C). Bovine embryos (Day6.5–7.5) collected from superovulated cows were classified according to developmental stages and morphological qualities (Grade 1 and 2) before cryopreservation and they were transferred to synchronized heifers after thawing. Pregnancy rates after transfer of morulae, early blastocysts and expanded blastocysts in Group V compared to Group C (54.5%, 12/22 vs. 56.0%, 14/25; 53.3%, 16/30 vs. 58.1%, 18/31 and 57.7%, 15/26 vs. 48.3%, 14/29) were not different (P > 0.05). Likewise, pregnancy rates after transfer of embryos of Grade 1 and 2 in Group V compared to Group C (55.1%, 43/78 vs. 54.1%, 46/85 and 36.4%, 12/33 vs. 32.9%, 23/70, respectively) were not different (P > 0.05). The study demonstrated similar viability of embryos which were frozen by vitrification or conventional method irrespective of their quality and developmental stage after transfer into recipients.

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Optimizing the conventional method of sperm freezing in liquid nitrogen vapour for Wallachian sheep conservation program

Czech Journal of Animal Science ◽

10.17221/226/2020-cjas ◽

2021 ◽

Vol 66 (No. 2) ◽

pp. 55-64

Author(s):

Filipp Georgijevic Savvulidi ◽

Martin Ptacek ◽

Anezka Malkova ◽

Jakub Beranek ◽

Ludek Stadnik

Keyword(s):

Liquid Nitrogen ◽

Conventional Method ◽

Membrane Damage ◽

Mitochondrial Activity ◽

Freezing Method ◽

Plasma Membrane Damage ◽

Freezing Procedure ◽

Ram Sperm ◽

Sperm Freezing ◽

Conventional Freezing

The aim of the present study was to optimize the conventional method of sperm freezing in liquid nitrogen (LN2) vapour for successful cryopreservation of Wallachian ram sperm, the genetic resources of the Czech Republic. Sperm in straws were frozen using the conventional freezing method via a static exposure of sperm doses to LN2 vapour, or by four different modified freezing methods. Under modified freezing, straws were frozen by a discontinuous, time-dependent decremental change in the distance between the straws and the surface of LN2. The viability of sperm was evaluated by flow cytometry after sperm equilibration, and immediately after thawing. Besides the observed inter-sire and daily variation, the obtained results suggest the methodological weakness of the conventional freezing method via the static exposure of sperm doses to LN2 vapour. With the use of the optimized freezing procedure, all parameters of thawed sperm were significantly (P < 0.05) improved in comparison with the conventional method: percentage of thawed sperm viability increased up to 48.3%, percentage of sperm with plasma membrane damage after thawing decreased to 6.58%, percentage of sperm with acrosome damage decreased to 24.4%, and percentage of sperm with deteriorated mitochondrial activity decreased to 6.28%. In conclusion, our results suggest that an optimized freezing procedure should be routinely used instead of the conventional method to cryopreserve Wallachian ram sperm.

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Methods for making stereoslides and -prints, with freeze-etched olfactory epithelium as example

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113408 ◽

1984 ◽

Vol 42 ◽

pp. 704-705

Author(s):

Bert Ph. M. Menco ◽

Ido F. Menco ◽

Frans L.T. Verdonk

Keyword(s):

Electron Microscope ◽

Olfactory Epithelium ◽

Three Dimensional ◽

Supporting Cell ◽

Structural Features ◽

Extensive Study ◽

Sprague Dawley ◽

Freezing Method ◽

Respiratory Epithelia ◽

Three Dimensional Presentation

Previously we presented an extensive study of the distributions of intramembranous particles of structures in apical surfaces of nasal olfactory and respiratory epithelia of the Sprague-Dawley rat. For the same structures these distributions were compared in samples which were i) chemically fixed and cryo-protected with glycerol before cryo-fixation, after excision, and ii)ultra-rapidly frozen by means of the slam-freezing method. Since a three-dimensional presentation markedly improves visualization of structural features micrographs were presented as stereopairs. Two exposures were made by tiling the sample stage of the electron microscope 6° in either direction with an eucentric goniometer. The negatives (Agfa Pan 25 Professional) were reversed with Kodak Technical Pan Film 2415 developed in D76 1:1. The prints were made from these reversed negatives. As an example tight-junctional features of an olfactory supporting cell in a region where this cell conjoined with two other cells are presented (Fig. 1).

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Cryosectioning plant roots prepared by high-pressure freezing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127748 ◽

1987 ◽

Vol 45 ◽

pp. 662-663

Author(s):

R.E. Crang ◽

M. Mueller ◽

K. Zierold

Keyword(s):

High Pressure ◽

Cell Walls ◽

Plant Tissues ◽

Ice Crystal ◽

High Pressure Freezing ◽

Vitreous State ◽

Radial Depth ◽

Irregular Topography ◽

Considerable Depth ◽

Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

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