The use of nucleus transfer techniques to generate transgenic dairy goats capable of producing recombinant therapeutic proteins in milk could have a major impact on the pharmaceutical industry. However, transfection or gene targeting of nucleus transfer donor cells requires a long in vitro culture period and the selection of marker genes. In the current study, we evaluated the potential for using caprine mammary gland epithelial cells (CMGECs), isolated from udders of lactating F1 hybrid goats (Capra hircus) and cryopreserved at Passages 24 to 26, for nucleus transfer into enucleated in vivo-matured oocytes. Pronuclear-stage reconstructed embryos were transferred into the oviducts of 31 recipient goats. Twenty-three (74%), 21 (72%), and 14 (48%) recipients were confirmed pregnant by ultrasonography on Days 30, 60, and 90, respectively. Four recipients aborted between 35 and 137 d of gestation. Five recipients carried the pregnancies to term and delivered one goat kid each, one of which subsequently died due to respiratory difficulties. The remaining four goat kids were healthy and well. Single-strand conformation polymorphism analysis confirmed that all kids were clones of the donor cells. In conclusion, the CMGECs remained totipotent for nucleus transfer.

Cellular array morphology has been examined in the shallow cell, deep cell, and cell-to-dendrite transition regime in Pb-2.2 wt pct Sb and Al-4.1 wt pct Cu alloy single-crystal samples that were directionally solidified along [100]. Statistical analysis of the cellular spacing distribution on transverse sections has been carried out using minimum spanning tree (MST), Voronoi polygons, radial distribution factor, and fast Fourier transform (FFT) techniques. The frequency distribution of the number of nearest neighbors and the MST parameters suggest that the arrangement of cells may be visualized as a hexagonal tessellation with superimposed 50 pct random noise. However, the power spectrum of the Fourier transform of the cell centers shows a diffused single-ring pattern that does not agree with the power spectrum from the hexagonal tessellation having a 50 pct superimposed random (uniformly distributed or Gaussian) noise. The radial distribution factor obtained from the cells is similar to that of liquids. An overall steady-state distribution in terms of the mean primary spacing is achieved after directional solidification of about three mushy-zone lengths. However, the process of nearest-neighbor interaction continues throughout directional solidification, as indicated by about 14 pct of the cells undergoing submerging in the shallow cell regime or by an increasing first and second nearest-neighbor ordering along the growth direction for the cells at the cell-to-dendrite transition. The nature of cell distribution in the Al-Cu alloy appears to be the same as that in the Pb-Sb. The ratio between the upper and lower limits of the primary spacing, as defined by the largest and the smallest 10 pct of the population, respectively, is constant: 1.43±0.11. It does not depend upon the solidification processing conditions.

Pb-2.2wt% Sb alloy was directionally solidified along [100], [110] and [111] crystallographic orientations using pure lead single crystal seeds, with a positive thermal gradient of 140Kcm−1 and growth rate of 10μms−1, and then quenched. Longitudinal (parallel to the growth direction) and transverse microstructures in the mushy region and in the quenched portion ahead of the solidification front were examined to investigate the morphology of primary dendrites solidified along different crystallographic orientations. Transverse microstructures showed that for growth along [100] the primary dendrites had the usual four-fold symmetry due to side-branching; for [110] orientation, they appeared plate like; while for [111] orientation, a uniform distribution of nodes was observed. These observations confirm that side-branches in FCC metal alloys grow along 〈100〉 crystallographic directions irrespective of heat-extraction direction.

The Pb-5.8 wt pct Sb alloy was directionally solidified with a positive thermal gradient of 140 K cm −1 at a growth speed ranging from 0.8 to 30 µ m s −1 , and then it was quenched to retain the mushy zone morphology. The morphology of the mushy zone along its entire length has been characterized by using a serial sectioning and three-dimensional image reconstruction technique. Variation in the cellular/dendritic shape factor, hydraulic radius of the interdendritic region, and fraction solid along the mushy zone length has been studied. A comparison with predictions from theoretical models indicates that convection remarkably reduces the primary dendrite spacing while its influence on the dendrite tip radius is not as significant.

The alloys Pb-2.2 wt pct Sb and Pb-5.8 wt pct Sb were directionally solidified with three different thermal gradients of 40, 86, and 140 K cm−1 at growth rates ranging from 0.6 to 30 µm s−1. A Gaussian peak amplitude analysis of the cell/dendrite spacing distribution shows a distinct peak corresponding to the nearest neighbors. The peaks corresponding to the second and the third nearest neighbor spacings are also brought out by this technique. The ratios of the second to the first nearest neighbor spacings and that of the third to the first neighbor spacings are 1.85 ± 0.11 and 2.70 ± 0.25, respectively. This indicates that the cells and dendrites both have a hexagonal distribution with a significant amount of superimposed noise. This is also confirmed by the frequency distribution of their number of nearest neighbors (coordination number).

Cellular/dendritic array tip morphology has been examined in directionally solidified and quenched Pb-5.8 wt pct Sb alloy by a serial sectioning and three-dimensional image reconstruction technique. There is a large scatter in the tip radius, the nearest neighbor spacing, and the mushy zone length, even among the immediately neighboring cells and dendrites. This scatter may be caused by the natural convection (in the mushy zone and in the bulk melt at the array tip), which also produces macrosegregation along the length of the directionally solidified samples. Even in the presence of convection, however, the tip radii are observed to be approximately proportional to the square of the primary spacings, and the radii are in a good quantitative agreement with the predictions from the model due to Hunt-Lu.