Gametogenesis and embryogenesis are dynamic developmental stages marked by 
extensive modifications in the organization of the genome and nuclear 
architecture. In the literature it is conveyed that only B-type lamins are 
required in these early stages of development and that A-type lamins are not 
present or required until differentiation of specific cell types associated with 
specialized tissue is initiated. To assess the presence of nuclear structures 
that are putatively involved in genome regulation, we investigated the 
distribution of lamin proteins throughout the early stages of porcine embryonic 
development, using testes tissue sections, oocytes and in-vitro fertilized (IVF) 
porcine embryos and employing anti-lamin antibodies. We have shown that 
anti-lamin A staining is present at the one-cell, two-cell, four-cell, and six- 
to eight-cell stages of early porcine embryo development, but diminishes at the 
morulae and blastocyst stages. Large intranuclear anti-lamin A foci are 
prominent in the early preimplantation stages. Both anti-lamin A/C and 
anti-lamin B staining were clearly present in all embryonic stages. Immature 
porcine oocytes revealed lamin rings using the monoclonal anti-lamin A/C 
antibody and many immature oocytes exhibited a pale rim staining pattern with 
anti-lamin A antibody. A-type lamins were not observed in sperm precursor cells. 
Thus, we have shown that A-type lamins and B-type lamins are present at the 
nuclear envelope in very early porcine embryos and that lamin A is also found in 
large intranuclear aggregates in two-cell to eight-cell embryos but is lacking 
from later embryonic stages.