The early development of the goat (Capra hircus).

Despite the vast amount of literature and study devoted to early mammalian development, there are few available references which deal with the early cleavage stages in the goat. So far as we can ascertain, only two observations have been made on the living goat egg; one by Krause (1837) who measured three ripe ovarian eggs, using a measurement open to doubt, but from which Hartman (1929) estimated the size of the living goat egg to be of the order of 140,u, a figure which is remarkably close to the average diameter of 145-3 L for the ova measured in the present investigation; the other by Amoroso, Griffiths & Hamilton (1939b) who described and figured tubal eggs in the one-cell, two-cell and four-cell stages. Assheton's (1908) youngest of five specimens (copulation age 5 days 20 hr.) had already left the tube and is at a stage in development comparable to the oldest of the uterine eggs we describe. The only other contribution is that of Tsukaguchi (1912), who described several stages of the goat's blastocyst (age not stated), the earliest of which corresponds closely to Assheton's specimen of the sixth day. Like Assheton, Tsukaguchi does not describe or figure the segmenting stages. The present contribution attempts to complete the lacunae in our knowledge in both these respects.