In the domestic pig, Sus scrofa, sexual dimorphism, as indicated by the presence of the sex chromatin body, is detectable in neurones of the brain and spinal cord (Cantwell, Johnston & Zeller, 1958; Hay & Moore, 1961; Harvey, 1969). Attempts to detect this feature in non-nervous tissue have, with one exception, failed. Hoshino & Toryu (1958) claimed to be able to demonstrate sexual dimorphism in eleven such tissues but these findings have not been substantiated (Hay & Moore, 1961; Harvey, 1969).
During a study on sex chromatin in various tissues including nervous tissue, liver and skin (Harvey, 1969), it was decided to examine foetal tissues including amnion. It was considered that this latter tissue might be suitable for demonstrating sex chromatin, such a feature having been demonstrated in man (Klinger, 1957)