Fetal bovine serum and virus, endotoxin, haemoglobin, IgG and total protein assays. Ethical questions have been raised regarding the blood collection process due to the potential suffering caused to the fetus. Although anoxia or active slaughter could be used to induce unconsciousness or death prior to serum harvesting, exposure of live unborn calves to oxygen can cause them to gain awareness before being killed, resulting in active debate about the ethics of harvesting serum. Fetal bovine serum is commercially available from many manufacturers, and because cells grown in vitro are highly sensitive, customers usually test specific batches to check for suitability for their
Blood, Sweat & Tears (Blood, Sweat & Tears album) City. The studio had just taken delivery of one of the first of the model MM-1000 16-track tape recorders, built by Ampex. The new technology allowed for far more flexibility in overdubbing and mixing than the 4 and 8-track tape recorders which were standard in 1968. The album was among the very first 16-track recordings released to the public. An additional song, "Children of the Wind" was recorded for the album but was not included. It later appeared on the compilation, "The Very Best of Blood, Sweat and Tears: What Goes Up!" The album was selected for the 2006 book