Thus we have, in a very limited field of research, briefly touched upon the relationship of the purely descriptive and experimental embryologist as to the methods of approach which each has taken in searching for the truth. The former points out the difficult barriers in the path of his progress. His judgment ofter later proves to be amazingly accurate in spite of the limitations of the methods...

The Clinical Embryologist is committed to reporting accurate, significant and up-to-date information concerning issues of importance to clinical laboratory embryologists, andrologists and those professionals engaged in the field of human assisted reproductive technology (ART) and infertility medicine. Dear Readers, Our theme this issue is " New Discoveries " and discoveries can come from any as...

The evolutionary embryologist Gavin Rylands de Beer can be viewed as one of the forerunners of modern evolutionary developmental biology in that he posed crucial questions and proposed relevant answers about the causal relationship between ontogeny and phylogeny. In his developmental approach to the phylogenetic phenomenon of homology, he emphasized that homology of morphological structures is ...

There are two main reasons why sperm may be absent from semen. Obstructive azoospermia is the result of a blockage in the male reproductive tract; in this case, sperm are produced in the testicle but are trapped in the epididymis. Non-obstructive azoospermia is the result of severely impaired or non-existent sperm production. There are three different sperm-harvesting procedures that obstructiv...

The objective of this retrospective study was to evaluate the factors influencing developmental stage of bovine embryos recovered from superovulated dairy cattle 7 d after estrus. From 217 superovulated dairy cows and heifers, 2,211 eggs were recovered, of which 1,495 were classified as transferable embryos based on morphological evaluation of developmental stage and quality. From the evaluated...